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Interplanetary Exploration: Application of the Solar Sail and Falcon Heavy

Gregory Matloff’s contributions to interstellar studies need scant introduction, given their significance to solar-and beamed sail development for decades, and their visibility through books like The Starflight Handbook (1989) and Deep Space Probes (2005). A quick check of the bibliography online will demonstrate just how active Greg continues to be in analyzing the human future in space, as well as his newfound interest in the nature of consciousness (Star Light, Star Bright, 2016). The paper that follows grows out of Greg’s presentation at the 2016 iteration of the Tennessee Valley Interstellar Workshop, where he discussed ways to advance deep space exploration using near term technologies like Falcon Heavy, in conjunction with the solar sail capabilities he has so long championed. Read on for an examination of human factors beyond lunar orbit and a description of a useful near-term mission that could reach an object much closer than Mars relying on both chemical and sail capabilities. Dr. Matloff is a professor of physics at New York City College of Technology, CUNY.


The possibility of applying the Space-X Falcon-Heavy booster to human exploration of the inner solar system is discussed. A human-rated Dragon command module and an inflatable habitat module would house and support the 2-4 person crew during a ~1 year interplanetary venture. To minimize effects of galactic cosmic rays, older astronauts should conduct the mission during Solar Maximum. Crew life support is discussed as is application of a ~1-km square solar photon sail. The sail would be applied to rendezvous with the destination Near Earth Object (NEO) and to accelerate the spacecraft on its return to Earth. An on-line NASA trajectory browser has been used to examine optimized trajectories and destinations during 2025-2026. A suitable destination with well established solar-orbital parameters is Asteroid 2009 HC. Because the NASA Space Launch System (SLS) has a greater throw mass than the Falcon-Heavy, the primary propulsion for NEO rendezvous and Earth return would likely be a chemical rocket. The sail would be used in this case as an abort mechanism and a back-up for the primary propulsion system. In either scenario, a single Falcon-Heavy or SLS launch would be adequate.

Keywords: NEO Exploration, Falcon-Heavy, Dragon, BEAM, GCR, ECLSS, SLS


The United States is currently developing two separate approaches to launching inner solar system exploration by human crews beginning in around 2020: the NASA Space Launch System (SLS) and the commercial Space-X Falcon Heavy [1,2]. The advantage of the SLS is its greater throw-weight on interplanetary trajectories. A disadvantage of SLS is the cost permission and constraints imposed by the current state of the US federal government. Although Falcon-Heavy has less launch capacity than the SLS, this booster is a composite of three existing and mass produced Falcon-9 boosters. These have an excellent reliability record to date on NASA-sponsored resupply missions to the International Space Station (ISS) and commercial launches. Experiments indicate that the Falcon 9 first stage may eventually be recovered and reused, which promises to greatly reduce the cost of space missions to low Earth orbit (LEO) and beyond.

This paper concentrates upon interplanetary ventures using a single Falcon-Heavy launcher and a small crew (2-4 people). As well as a Dragon V2 capsule appropriately modified for interplanetary application (3), an inflatable Bigelow space habitat similar to the one to be launched to the ISS [4} in the near future will be used for crews habitability. Life support for the crew on their 1-2 year interplanetary venture will utilize recycling of oxygen and water. Food recycling by biological means will likely not be ready by 2020.

After the spacecraft is launched towards Mars, a state-of-the-art solar photon sail with a dimension of ~0.7 km will be unfurled. This will allow, as will be demonstrated, non-rocket accelerations of 1-2 km/s per month in the solar system region between Earth and Mars.

A recent comprehensive study of in-space radiation effects reveals that galactic cosmic radiation beyond LEO is reduced by a factor of ~5 above LEO, if missions are conducted during solar maximum. During solar flares and coronal plasma discharges, the crew could be protected by aligning the Dragon’s heat shield between the crew quarters and the Sun.

Human landings on Mars will not be possible using a single Dragon launch. But a host of Near Earth Objects of asteroidal and cometary origin and possibly the Martian satellites Deimos and Phobos will be open to human explorers.

But any human expedition beyond the Moon will likely require cruise durations of months to years. Solar and galactic cosmic radiation will certainly be a limiting issue. The possibilities and effectiveness of using the capsule and habitat mass for self shielding is discussed in the next section.

Falcon-Heavy Interplanetary Throw Mass and Cosmic Ray Shielding

According to Ref. 2, a Falcon-Heavy is capable of projecting 13,200 kg on a trans-Mars trajectory. From Ref. 3, the dry mass of a Dragon V2 capsule is 4200 kg and the endurance of this spacecraft is about 2 years in space. The mass of the BEAM inflatable module is 1360 kg [4].

From Ref. 3, the Dragon’s configuration can be approximated by a cone with a diameter of about 3.7 m and a height of about 6.1 m. From Ref. 4, the BEAM inflatable habitat can be approximated by a cylinder with a diameter of about 3.2 m and a length of about 4 m. Assuming that the base of the Dragon abuts one of the circular end caps of the BEAM, it is easy to demonstrate that the surface area of the spacecraft is about 100 m2. Assuming that all of the Falcon’s throw mass can be used for self-shielding against cosmic rays during an interplanetary venture, the approximate shielding areal mass thickness is 130 kg/m2 or 13 g/cm2.

There are two major sources of cosmic radiation beyond the Earth’s magnetosphere. These are eruptions of solar energetic particles (SEPs), which are most common during solar maximum and galactic cosmic rays (GCR), which are alway present. We first consider the effects of a 13 g/cm2 shield on SEPs.

Shielding From SEPs

A recent paper by an international team summarizes the latest results on cosmic ray shielding above LEO [5}. Figure 6 of that reference compares the Effective Dose Equivalent predicted to be incurred by an astronaut from four SEP events: a 20-year event, a 10-year event, a worst-case modeled event and a Carrington-event estimate. This data is plotted against aluminum shield thickness and compared with currently recommended European Space Agency (ESA) career dose limits. In all cases presented, a 13 g/cm2 aluminum shield is adequate.

Figure 7 of Ref. 5 presents similar information and compares predicted doses from the above SEP events with the 30-day and annual ESA limit. Once again, a 13 g/cm2 aluminum shield seems to be adequate, although the Carrington-event predicted dose rate is very close to the 30-day limit.

Therefore, SEPs do not seem to pose an insurmountable health risk to crews venturing beyond LEO with an equivalent a 13 g/cm2 aluminum shield. Additional shielding could be affected by orienting the Drago heat shield between crew and Sun during a major SEP event.

Shielding from GCRs

Galactic cosmic rays, on the other hand, pose a larger risk to the crew’s health. Since at least 1979, it was known that energetic galactic cosmic rays more massive than helium nuclei (high-Z GCR) are potentially dangerous to human health and very difficult to shield against [6]. Figure 1 of Ref. 5 reveals that during solar maximum, the modeled flux of galactic hydrogen and helium nuclei are reduced by a factor of 5-10 when compared with fluxes of the same ions during solar minimum. But the fluxes of galactic lithium and iron nuclei are apparently independent of the solar activity cycle.

Cucinotta and Durante estimate that during an interplanetary transfer, the high-Z GCR dose might be 1-2 mSv per day or 0.4-0.8 Sv per year [7]. From Tables 1 and 2 of McKenna et al, the NASA one-year dose limits for 40-year old female and male astronauts are respectively 0.7 and 0.88 Sv. For older astronauts, the limits are higher. Dose limits for men are higher than dose limits for women.

During a 1-year interplanetary voyage, the dose limits for 40-year old astronauts may be exceeded. Exposures beyond these recommended limits may result in a 3% increased risk of fatal cancers.

Health effects on interplanetary astronauts from high-Z galactic cosmic rays is an ongoing field of research. Mewaldt et al. also conclude that interplanetary voyagers will experience a higher galactic dose during solar minimum than during solar maximum. According to their study, a thin aluminum shield of about 3 g/cm2 may reduce solar minimum dose rates to the NASA LEO career limit of 50 cSv for a 1-year interplanetary round trip [8].

It should also be mentioned that it is not always possible to predict future GCR doses in interplanetary space from data obtained during previous solar cycles. Schwadron et al have noted that unusually high levels of GCRs were measured during a prolonged solar minimum in 2009 [9].

Crew Life Support on Interplanetary Ventures

We next consider the mass requirements to maintain a small crew (2-4 people) during a 1-2 year interplanetary expedition. According to the wikipedia entry on space-life-support systems and in substantial concurrence with one classic reference [10], daily average human metabolic requirements can be summarized:

oxygen: 0.84 kg
food: 0.62 kg
water: 3.52 kg.

If partial recycling were not built in to the mission, a two-person crew could not be supported in the proposed spacecraft for missions of one year or longer. Projections from International Space Station technology indicate that a near-term goal for water recycling is 85% and the oxygen recovery rate can be raised to 75% [11,12]. Applying these values for an interplanetary mission applying near-term recycling technology, the daily consumable requirement per astronaut is 0.21 kg oxygen, 0.62 kg food, and 0.53 kg of water. Each crew member consumes about 1.4 kg per day of these resources or about 500 kg per year. A 4-person crew therefore requires about 2,000 kg of these resources for a 360-day duration interplanetary voyage.

It is next necessary to estimate the mass of the Environmental Control and Life Support System (ECLSS) equipment, not including consumables, necessary to support the mission. In Table 4.3 of his monograph, Rapp estimates the mass of the water-recovery system for a 180-day transit to Mars at 1.4 metric tons or 1,400 kg and the mass of the oxygen recovery system at 0.5 metric tons or 500 kg for a 6-person crew [13]. We are here considering a smaller crew and the 180-day return voyage as well as the 180-day flight to the interplanetary destination. Since we have no idea regarding ECLSS reliability on a deep-space mission, we will assume here that the required mass of ECLSS equipment is 3,000 kg. Including the 2,000 kg requirement for oxygen, food and water, the total ECLSS mass is about 5,000 kg.

Application of a Near-Term Solar Photon Sail

From the above discussion, the mass of the Dragon is estimated at 4,200 kg and the BEAM habitat mass is 1,360 kg. Since the Falcon-Heavy can project 13,200 kg towards Mars and our ECLSS mass projection is 5,000 kg, the remaining mass amounts to 2,640 kg. If 640 kg is required for scientific equipment, 2,000 kg remains to be allowed. We will therefore assume that the sail mass is 2,000 kg.

As an example of a large solar-photon sail that could be constructed in the not very distant future, we consider a 90% reflective (REF) opaque 1-km2 sail with an areal mass density of 2 g/m2. The sail mass is 2,000 kg and the areal mass density of the spacecraft (σeff) is 0.0132 kg/m2.

The lightness factor (β) of a solar-photon sail is the ratio of solar radiation-pressure acceleration on the sail to solar gravitational acceleration. It can be calculated by modifying Eq. (4.19) of Ref.14 for a solar constant of 1,366 W/m2:

Substituting in Eq. (1) for sail reflectivity and spacecraft areal mass density, we find that β = 0.11.

Since the Earth is in a near-circular solar orbit at a distance of 1 Astronomical Unit (1 AU = 1.5 X 1011 m) and the Earth’s solar-orbital velocity is about 30 km/s, the Sun’s gravitational acceleration on the spacecraft at a distance of 1 AU is about 0.006 m/s2. The solar radiation-pressure acceleration on the sail is therefore about 6.6 X 10-4 m/s2, if the sail is normal to the Sun at a distance of 1 AU from the Sun. Such a sail configuration can result in a daily velocity increment of about 57 m/s. Every month, the sail can alter the spacecraft velocity by about 1.6 km/s, if it is oriented normal to the Sun at a solar distance of 1 AU. At the orbit of Mars (1.52 AU), this sail oriented normal to the Sun can alter the spacecraft’s solar velocity each month by about 0.69 km/s.

The effectiveness of this configuration for non-landing missions to Mars can be evaluated using Table 4.2 of Ref. 15. The duration of a Hohmann minimum-energy Earth-Mars trajectory is given in that table as 259 days. Although application of the sail can shorten this a bit on the Mars-bound trajectory, sail or some other form of propulsion must be used to accomplish Mars rendezvous. Aerocapture with a deployed sail of this size will be difficult or impossible. Table 4.2 of Ref. 15 also presents Earth-Mars transit times for spacecraft flying a logarithmic spiral trajectory at a sail pitch angle relative to the Sun of about 35 degrees, as a function of lightness factor. For β = 0.1, the time required for a return journey on such a trajectory is about 431 days. To accomplish logarithmic-spiral Earth-return trips from Mars approximating the Hohmann-trajectory duration with the spacecraft configuration considered here would require a substantial increase in sail area without an increase in spacecraft mass. More advanced sails, smaller crews, or less massive ECLSS would be required.

Application of Falcon/Dragon/BEAM for NEO Exploration

So the configuration presented here is marginal at best for Mars-vicinity missions such as exploration of the natural Martian satellites Phobos and Deimos. Instead, it might see more immediate application to near Earth objects (NEOs) orbiting the Sun close to the Earth’s solar orbit.

A suitable target NEO for such an expedition would be in a near-circular, low-inclination orbit approximately 1-AU from Earth. If the mission is timed appropriately, the Hohmann trajectory duration should be considerably less than the time required to reach Mars and the Falcon-Heavy payload should be greater than that estimated for a Mars mission. One NEO class of potential targets is Earth’s quasi-satellites in “corkscrew orbits” [16].

The principal use of the sail on the out-bound trajectory leg would be deceleration for rendezvous with the NEO. The sail would be used to accelerate the spacecraft for Earth rendezvous on the return trajectory leg. Although the Sail and BEAM inflatable habitat could be maneuvered into Earth orbit for possible reuse, the Dragon would return crew and payload (including NEO samples) to Earth in a ballistic reentry.

It is possible to investigate mission possibilities with the aid of the NASA on-line Trajectory Browser (trajbrowser.arc.nasa.gov). After accessing this site on May 23 and 25, 2015, we specified a mission to a NEO with a well established orbit during the next solar-max (2025-2026) to reduce crew exposure to GCRs. Two mission types were considered: a round-trip with a maximum duration of 360 days and a one-way, rendezvous mission with a maximum duration of 180 days. For the one-way rendezvous mission, the maximum delta-V for departure from a 200-km low-Earth orbit was 4 km/s. For the round-trip. the maximum delta-V was 5 km/s.

The results of this exercise are presented in Table 1 [following the references]. The destination NEO determined by the Trajectory Browser software is Asteroid 2009 HC. Browser output is summarized in Table 1. This table also includes physical data on this NEO from the NASA Jet Propulsion Laboratory NEO data base (ssd.jpl.nasa.gov).

It is assumed that the pre-rendezvous propulsion requirements will be met by the Falcon upper stage, since this configuration is capable of reaching Mars, a more distant destination. Since the post-injection delta-V is small and the sail’s characteristic acceleration at 1 AU is greater than 1 km/s, the sail can be used to match velocity with the destination NEO without significantly increasing pre-rendezvous mission duration.

Note from Table 1 that the difference between post-injection delta-V for one-way rendezvous and round-trip missions is less than 1 km/s. So it is safe to assume that use of the sail to power Earth-return maneuvers does not significantly increase mission duration.

Another way to consider use of the sail on the Earth-bound trajectory is to estimate time required for the sail to be used for orbital inclination adjustment or “cranking”. From Eq. (5-74 of McInnes’s monograph [15]), a sail operating at the optimal cone angle can change its inclination by

∆ i = 88.2 β degrees/orbit. (2)

According to McInnes, Equation (2) is independent of solar-orbit radius. Inclination correction for Earth-return will add a few months to the duration of the round-trip mission.

Conclusions: Use of the Sail with the NASA Space Launch System on NEO-Visit Missions

From the work presented here, it seems that round-trip visits to selected Near Earth Objects with durations not much greater than one year can be accomplished using a single Falcon-Heavy launch and a combination of a Dragon spacecraft, an inflatable habitability module, state of the art partially closed environmental system and a state of the art square solar photon sail with a 1-2 km dimension.

To reduce the Galactic Cosmic Radiation risk to the 3-4 person crew, it is advisable to conduct lengthy voyages above Low Earth Orbit during periods near the maximum of the solar activity cycle and to position the Dragon heat shield facing the Sun to shield against solar flare events. It may also be advisable to select older astronauts to crew such interplanetary ventures.

If the NASA Space Launch System is available to conduct human visits to suitable NEOs, the sail could serve at least two functions. Because the SLS has 2-3X the throw mass of the Falcon-Heavy, the sail could be accommodated as a pre-rendezvous abort option or as a back-up to the SLS propulsion module for Earth-return maneuvers.

It should also be mentioned that with either launch alternative, the sail and inflatable could be steered into high-Earth orbit for reuse after the Dragon or Orion is directed on its Earth reentry path.


1. “NASA Fact Sheet: NASA Space Launch System”, www.nasa.gov/pdf/ 664158main_sls_fs_master.pdf

2. “Falcon Heavy”, www.spacex.com/falcon-heavy

3. “Dragon V2), en.wikipedia.org/wiki/Dragon_V2

4. “The Bigelow Expandable Activity Module (BEAM),” bigelowaerospace.com/beam

5. S. McKenna-Lawlor, A. Bhardwaj, F. Ferrari, N. Kuznetsov, A. K. Lal, Y. Li, A. Nagamatsu, R. Nymmik, M. Panasyuk, V. Petrov, G. Reitz, L. Pinsky, M. Shukor, A. K. Singhvi, U. Strube, L. Tomi, and L. Townsend, “Recommendations to Mitigate Against Human Health Risks Due to Energetic Particle Irradiation Beyond Low Earth Orbit/BLEO”, Acta Astronautica, 109, 182-193 (2015).

6. E. Bock, F. Lambrou Jr., and M. Simon, “Effect of Environmental Parameters on Habitat Structural Weight and Cost”, Chap. II-1 in Space Resources and Space Settlements, NASA SP-428, J. Billingham and W. Gilbreath eds., NASA Ames Research Center, Moffett Field, CA (1979).

7. F. A. Cucinotta and M. Durante, “Cancer Risk from Exposure to Galactic Cosmic Rays: Implications for Space Exploration by Human Beings,” Lancet Oncology, 7, 431-435 (2006).

8. R. A. Mewaldt, A. J. Davis, W. R. Binns, G. A. de Nolfo, J. S. George, M. H. Israel, R. A. Leske, E. C. Stone, M. E. Wiedenbeck and T. T. von Rosenvinge, “The Cosmic Ray Radiation Dose in Interplanetary Space—Present Day and Worst-Case Evaluations”, Proceedings of the 29th International Cosmic Ray Conference, Pune, India, August 3-10, 2005, B. Sripathi Acharya, S. Gupta, P. Jagadeesan, A. Jain, S. Karthikeyan, S. Morris and S. Tonwar eds., ( Tata Institute for Fundamental Research, Mumbai, India, 2005), pp. 433-436.

9. N. A. Schwadron, A. J. Boyd, K. Kozarev, M. Golightly, H. Spence, L. W. Townsend and M. Owens, “Galactic Cosmic Ray Radiation Hazard in the Unusual Solar Minimum Between Solar Cycles 23 and 24”, Space Weather, 8, DOI: 10.1029/2010SW000567, (2010).

10. M. R. Sharpe, Living in Space: The Astronaut and His Environment, Doubleday, Garden City, NY (1969).

11. R. Carrasquillo, “ISS Environmental Control and Life Support System (ECLSS) Future Development for Exploration”, presented at 2nd Annual ISS Research and Development Conference (July 16-18, 2013).

12. M. Gannon, “NASA Wants Ideas to Recycle Precious Oxygen on Deep-Space Voyages”, www.space.com/25518-nasa-oxygen-recycling-space-tech.html (space.com, April 16, 2004).

13. D. Rapp, Human Missions to Mars: Enabling Technologies for Exploring the Red Planet, Springer-Praxis, Chichester, UK (2008).

14. G. L. Matloff, Deep-Space Probes: To The Outer Solar System and Beyond, 2nd ed., Springer-Praxis, Chichester, UK (2005).

15. C. R. McInnes, Solar Sailing: Technology, Dynamics, and Mission Applications, Springer-Praxis, Chichester, UK (1999).

16. P. Wajer, “Dynamical Evolution of Earth’s Quasi-Satellites 2004 GU9 and 2006 FV35”, Icarus, 209, 488-493 (2010).

Table 1. Details for a NEO Visit in 2025-2026


Comments on this entry are closed.

  • Anton M. March 23, 2018, 14:36

    Does having a crew of four at the mission target pay for several TONS less of scientific equipment? Imagine all these supplies and life support replaced with scientific instruments. For NEO, one could literally tear chunks out of it, drill it, explode it, nuke it, map it, look inside it with radar, seismic, you name it – if you bring these tons of science payload there instead of four bags of biologic goo not really fit for the space environment.

    • Greg Matloff March 23, 2018, 16:59

      Dear Anton

      You are correct about the lower mass of a robotic craft. But space flight is also a human endeavor. I am very tired of decades of NASA and industry projections on how to go to Mars, asteroids, etc. My purpose in this exercise was to show that existing or near-term, not too expensive technology, could allow human missions to nearby asteroids.


      • Jens Knudsen March 25, 2018, 15:45

        There is also the question of time delay regarding the use of remote control of robotic equipment at ever larger distances from the Earth. We need people out there also.

        • Greg Matloff March 27, 2018, 10:08

          Dear Jens

  • Antonio March 23, 2018, 14:42

    “During a 1-year interplanetary voyage, the dose limits for 40-year old astronauts may be exceeded. Exposures beyond these recommended limits may result in a 3% increased risk of fatal cancers.”

    Nope. Why do people keep repeating that radiation BS?


    • Greg Matloff March 23, 2018, 17:01

      Dear Antonio

      That is why I went to the most authoritative rad study I know of. A 1-year trip can be done without too much rad risk. For longer duration missions, more shield mass or (perhaps) drugs or (perhaps) superconducting shields are necessary.


      • J. Jason Wentworth March 27, 2018, 15:17

        Foods rich in anti-oxidants (including bilberries, blueberries, and preserves and jams made from them) provide significant protection from the effects of radiation. Research by health physicists during the nuclear-powered airplane program revealed this. (During World War II, RAF–Royal Air Force–doctors also discovered that the night vision of their pilots was greatly improved by bilberry and blueberry preserves and jams [which was an important finding, since the RAF engaged in night-time bombing], although at the time they didn’t know why, so they encouraged RAF pilots to eat more of these foods.)

      • Antonio March 28, 2018, 8:11

        Dear Mr. Matloff,

        what study are you referring to? No source is cited in the 3% sentence. As for BEIR, it’s pretty much THE authoritative source, for the number of scientists involved, for the time spent (several decades, updated every decade or so), and because it’s produced by a government agency (the Committee on the Biological Effects of lonizing Radiation (CBEIR) of the National Research Council of the USA).

    • Anton M. March 23, 2018, 18:12

      The article contains a methodological error; actually, it is almost a classic strawman’s:
      “For example, a person can drink a glass of wine every night for a year without harmful effect, but drinking 100 glasses (let alone 365) in one night would be fatal. Yet, based on the linear hypothesis, one would falsely predict a 1 percent chance of death from a single glass. The linear hypothesis makes the same wild error in purposely overestimating radiation risk.”
      – the problem is, a high radiation dose received at once is less dangerous than an equivalent dose received over a prolonged period. It is because the most harmful effect of ionizing radiation is free radicals what damage biological molecules inside the cell. If there is a plenty of free radicals, they start to react and neutralize each other. It is quite the basics. Yet the article uses a false and misleading analogy. There are quite a few dose-effect curves in toxicology and trying to oversimplify the things does not help a lot.

      • Greg Matloff March 24, 2018, 7:20

        Please take up your radiation issues with the authors of the international, peer-reviewed Acta Astronautica paper that I cite. They are the ones you should bring your concerns to, not me! All I did was use the best available estimates, in as rational a manner as possible.

    • Anton M. March 23, 2018, 18:20

      P.S. What is even funnier, there was the extensive research of radiation protectors in the military and some substances allegedly increase the effective fatal dose by the order of magnitude at least. Again, it all was focused on the acute effects (“the law of sevens”) rather than chronic ones, but there might be a way to increase the human body tolerance with a few pills rather than a few tons of shielding.

  • Antonio March 23, 2018, 14:52

    And, of course, there are a dozen cosmonauts and astronauts who have already received Mars mission equivalent GCR doses (Padalka, Malenchenko Avdeyev, Polyakov, Solovyov, Krikalyov, Titov, Manarov, Foale, Fincke, Pettit, Walz, Kelly, Whitson) during extended space missions without any radiological casualties.

    • Greg Matloff March 23, 2018, 17:03

      Dear Antonio

      But none of them have been above Earth’s protective magnetosphere for longer than about two weeks. In LEO, rad dose is halved by Earth blocking.


      • Antonio March 28, 2018, 7:58

        Dear Greg Matloff,

        Sorry for the delay.

        “But none of them have been above Earth’s protective magnetosphere for longer than about two weeks.”

        Sorry, what?? Earth’s magnetosphere doesn’t protect against GCR. That’s why, as you correctly say in the next sentence:

        “In LEO, [GCR] rad dose is halved by Earth blocking.”

        If there were some protection from the magnetosphere, it would not be half, it would be less. It’s not an hypothesis, it’s a fact, it has been measured by several missions, as the links I posted above show.

        • Michael March 28, 2018, 16:29

          Approx Half of the radiation is blocked by the mass of the earth.

  • Andrew Palfreyman March 23, 2018, 17:07

    But BFR.

    • J. Jason Wentworth March 24, 2018, 2:39

      I’m confident that the BFR will fly (and that the “F” really refers to an acronym–which the Puritans, of all people, developed [it was printed on the stocks in which convicted adulterers had to stand]–that stands for “For Unlawful Carnal Knowledge”…), but until it flies, the BFR is still a “paper rocket,” whose performance capabilities are unproven. The Falcon Heavy has now flown, and it may prove to be cheaper (in total launch cost, if not dollars per kilogram to orbit). Also, Greg’s Falcon Heavy-sized solar sail NEO spaceship is probably cheaper than a larger one sized to fly aboard the BFR.

      • Greg Matloff March 24, 2018, 7:23

        Dear Jason



    • Greg Matloff March 24, 2018, 7:22

      BFR is a good candidate for interplanetary missions, at least on paper. But it has yet to fly.

  • David Gill March 23, 2018, 21:40

    Falcon Heavy will probably not be human-rated for years, given a relatively low launch cadence- it seems the need for heavy commercial satellites is on the wane due to miniaturization. Therefore, in the near term, a more likely scenario would be a Falcon Heavy launch carrying the cargo and inflatable infrastructure for the flight, and a Falcon 9 to launch the Crew Dragon, with rendezvous in LEO. This improves the outlook for payload and reducing travel times,especially if we also envision a fuel depot in LEO…
    I also wouldn’t hold my breath for the SLS to ever fly more than demonstration flights.

    • Greg Matloff March 24, 2018, 16:05

      Dear David

      Yours might be a better scenario.


    • Brett Bellmore March 25, 2018, 12:31

      Neither delay is an issue, in as much as the report suggests flying at Solar maximum, and we’re presently entering a Solar minimum. Falcon Heavy is likely to be manrated well before any Solar maximum. Probably BFR, too.

      And, personally, I’d be surprised by even a demonstration flight of the SLS, given how obviously redundant it’s likely to be before there’s flight ready hardware.

      • Greg Matloff March 27, 2018, 10:10

        Dear Brett

        Very unfortunately, you may well be correct about SLS.


  • Curious March 23, 2018, 23:39

    Interesting analysis! In case Dr. Matloff is not familiar with the history of NASA inflatable work he can go to https://ntrs.nasa.gov/ and search for “TransHab” – this was the much larger forebearer of Bigelow BEAM and Galaxy modules. TransHab was heavily tested at NASA JSC and analyzed, and the info from those efforts is posted in various papers in ntrs. These might help provide him with further information should he need it. For example several comparisons for Crew radiation were performed and it was found that the TransHab structure offered far superior protection over ISS’s aluminum walled modules. I recall there was also discussion that the cylindrical portion of the TransHab walls could be configured as drinking water tanks with the side benefit of providing about 36″ thickness of water wall shielding in addition to the regular TransHab walls.

    • Greg Matloff March 24, 2018, 7:25

      Dear Curious

      I know about TransHab. I consider Beam because it has flown. I suspect the TransHab rad estimates are for solar, not galactic radiation.


  • J. Jason Wentworth March 24, 2018, 4:00

    Such missions need to be flown, for psychological as well as engineering and scientific reasons. Through all of the plans and proposals for expeditions beyond the Moon runs a thread of fear, which contains two strands; one is called “radiation,” and the other is called “life support.” As far back as the 1960s Mars and Venus mission proposals (even the Apollo-Saturn V-based Bellcomm flyby ones), the need for radiation “storm cellars,” as they were called, was recognized, and:

    Long-term life support system reliability for interplanetary missions was more troubling, because the sudden deaths of all crew members would be more horrifying (with the attendant public reaction against NASA), which would be compounded by the very real possibility that they would never be laid to rest on Earth, but would be a stark monument to the space program, particularly if the accident occurred in solar orbit (this possibility haunted the Apollo 13 crew, who preferred even a fatal Earth impact to skipping back out of the atmosphere into space forever). A successful NEO expedition and safe return would help to dispel these old fears. Also:

    I have a two-part question and a suggestion for this proposed NEO mission. If the sail was positively charged (by ejecting electrons from the spacecraft with an electron gun), would that provide any meaningful electrostatic protection against SEPs and/or GCRs (if the sail “shadowed” the spaceship from the Sun’s SEPs [and shadowed the vessel from half of the sky’s GCRs])? (If so, perhaps a “box” of conductive sail material installed around the spacecraft would provide all-around electrostatic protection, or at least attenuation.) Also, would such a charged solar sail produce worthwhile additional thrust by repelling the solar wind particles? In addition:

    Drinking water recycling from urine has already been developed (Russian scientists successfully tested such a “urine still” for use aboard the Mir space station; the cosmonauts balked at it, but a derivative system partially recycles the air inside the ISS). Both systems could reduce the NEO spaceship’s mass. As well:

    A type of on-board solid waste recycling for food might also be possible now (or in the near term), and it could also reduce the NEO spaceship’s all-up weight. It involves something that a Vietnam veteran friend of mine told me about. In South Vietnam, the USAID agency personnel had taught catfish farmers how to save money on their fishes’ feed by installing communal outhouses on wooden bridges over their catfish ponds (they also taught small-scale farmers who raised both chickens and catfish to suspend the chickens’ cages over the catfish tanks; in both cases, the catfish fed off feces). Aboard the Skylab space station, minnows quickly adapted to microgravity, learning to visually orient themselves by accepting the visible wall as the “floor” of their tank, and catfish could probably do this as well.

    I hope this information will be helpful.

    • Greg Matloff March 24, 2018, 7:30

      Dear Jason

      Very nice comment. EM charge might alleviate solar cosmic rays. But at this point, I think that it won’t do much for galactic cosmic rays. Research is being done on this. It will be interesting if something like M2P2 results in a good, low-mass cosmic-rad shield.

      • J. Jason Wentworth March 26, 2018, 4:42

        To amplify on the comment by Curious, expandable hab module research at NASA goes back even further. One of the old (early 1970s) C.B. Colby books featured a test version of an inflatable module intended for extended lunar surface stays; it was a thick-walled, dome-ended cylinder with a spherical door/airlock module at one end. It didn’t have a central, rigid “core frame” like the TransHab and the (larger) Bigelow modules, and–based on the era–I suspect that it was developed from the early 1960s Goodyear and Langley Research Center expandable “doughnut” space stations (they were 30′ and 24′ in diameter, respectively, and a 150′ diameter one was under study, see: http://books.google.com/books?id=ISEDAAAAMBAJ&pg=PA96&lpg=PA96&dq=Inside+Our+First+Space+Station+Popular+Science+December+1962&source=bl&ots=giiWz9KMdE&sig=ZqXm1KGaOgq66mbKlidwH7gND9M&hl=en&sa=X&ved=0ahUKEwiF6NekxInaAhVJ6GMKHZzfCf4Q6AEIJzAA#v=onepage&q=Inside%20Our%20First%20Space%20Station%20Popular%20Science%20December%201962&f=false), and:

        These von Braun “wheel”-type stations were to be spun to provide artificial gravity (there were actually plans to orbit Goodyear’s 30′ one for testing–the 150′ one would have been better from the “centrifugal-gravity” standpoint). They were made of foam rubber sandwiched between fabric inner and outer layers, which was surprisingly meteoroid-resistant, as hyper-velocity glass pellet tests showed. (It took quite a wallop to penetrate all the way through the foam rubber, which acted like a thick Whipple Shield, spreading out an impactor’s energy, and patching holes was straightforward.) In the Apollo rush, this promising project–like so many others–fell by the wayside, but:

        With today’s materials, a Falcon Heavy could easily orbit a 150′ (or larger) expandable “all-in-one-shot” von Braun “wheel” station. It could even–if made of “pre-peg” (resin-pre-impregnated, vacuum-curing resin (another early 1960s development; see page 92 here: http://books.google.com/books?id=yCADAAAAMBAJ&pg=PA2&lpg=PA2&dq=Balloons+that+harden+in+space+Popular+Science&source=bl&ots=RDTQFZSu5o&sig=EKNbtofekQbuPoX7sjy8Vto9mlk&hl=en&sa=X&ved=0ahUKEwiUxcjQxonaAhXGLmMKHY0nCMQQ6AEIVjAJ#v=onepage&q=Balloons%20that%20harden%20in%20space%20Popular%20Science&f=false [it is also being worked on again today, using *radiation* curing: http://www.wired.com/2010/09/hard-space-polymers/ ])–self-rigidize, so that internal pressure wouldn’t be needed to keep it stiff. Also:

        The medical results of long microgravity exposure make it clear that we need 1 g to remain healthy and keep normal vision (maybe less would do for long periods, but we just don’t know–we *know* the 1 g works), and it’s well past time for NASA to get over its aversion to centrifugal artificial gravity. The radiation problem is bad enough without compounding it with the bone loss, the slight (but permanent) vision loss caused by optic nerve crushing due to excess fluid in the upper body, the permanent DNA alterations, and the other health problems resulting from prolonged exposure to microgravity. Magsail research might help lick the radiation problem, because of the work being done to develop high-temperature superconducting electromagnetic wire hoops.

      • J. Jason Wentworth March 26, 2018, 4:51

        Thank you. I wonder about the extra thrust, though (if the extra solar wind thrust acquired by positively charging the solar sail would be worth the added mass of the electron gun). I suspect that the answer may be. “it depends” (based on the specific spacecraft and mission profile). Solar wind thrust is weaker than solar photon thrust, yet for certain probes and missions, solar wind “wagon wheel” E-sails (and even single-wire E-sails, for very small probes) “pencil out” as being effective.

    • Alex Tolley March 25, 2018, 13:17

      There is a considerable mass tradeoff if the intention is to use fish living in tanks to “recycle” solid wastes. It might be better to just use energy to extract H2O and even O2 from the wastes and dump/store the dry residue. Keeping fish healthy even on a farm isn’t a slam dunk, and it would be a real problem for the crew if the fish sickened and died in the tanks. The smell wouldn’t be good, even with healthy fish tanks. :(

      • J. Jason Wentworth March 26, 2018, 5:09

        For a vehicle like SpaceCoach (or even for small attitude control, station-keeping, or minor trajectory correction ion thrusters on a solar sail ship), the solid waste could be freeze-dried (naturally and free of charge, “energy-wise”), then made into a fine powder and used as reaction mass (“dust-fueled” ion thrusters have been successfully ground-tested since the 1960s; careful internal component arrangement prevents them from being “sandblasted,” and they could also refuel from the regolith on asteroids and moons). Arthur C. Clarke also mentioned dust-fueled ion engines in his 1957 book, “The Making of a Moon: The Story of the Earth Satellite Program,” and:

        Another engine that is rather like a dust-fueled ion thruster is the NanoFET (see: https://www.centauri-dreams.org/?p=8647 and http://www.google.com/search?q=nanofet+propulsion&cad=h ), whose reaction mass nanoparticles are comparable in size to dust particles.

      • Greg Matloff March 27, 2018, 10:12

        Dear Alex

        Rather than dumping waste, it might be better to store it as GCR shielding. But, of course, the odor might be a problem!


        • Michael March 27, 2018, 12:15

          We could put it on the outside :)

          Mind you if we let the UV from the sun break it down it would form gases that can used in an ion engine.

    • ljk March 26, 2018, 10:57

      Speaking of Apollo 13, this computer study from 2010 shows what would have likely happened to the spaceship and crew if they had been unable to align themselves for a proper return to Earth:


    • Alex Tolley March 26, 2018, 14:08

      The solar wind provides far less momentum than the photons. To counter that, electric sails reduce their mass by using wires or magnetic fields to reduce their effective aerial density to maintain acceleration. Modifying a photon sail to try to harness the solar wind therefore probably does not add much thrust.

      Electric fields might be more useful as shielding, or possibly as a way to improve sail deployment.

  • AlexT March 24, 2018, 6:47

    Just wanderung, why there is no any reference to possibility to use electric/magnetic sheilding of spacecraft, as I understand the lithium amd iron nuclea – ate charged particles, so there is good chance to use electric/magnetic sheild as we have on the Earth.

    • Michael March 24, 2018, 16:11

      Placing a powerful positive charge on a thin metal sail towards the sun while moving the electrons to another part away from the sail on the opposite side should give better protection from solar protons.

  • Greg Matloff March 24, 2018, 7:27

    Dear AlexT

    At present, EM shielding is massive. I think such mass precludes its use on a Falcon Heavy interplanetary flight. But it is a great idea for the future.


    • AlexT March 24, 2018, 8:12

      Thanks for the answer, I suppose that there is good conditions for supercoductors use on the shadow side of the spacecraft, environment temperature is low enough , there is no need to use complex amd massive cooling systems as we do on the Earth.
      By the way before I read this article I was sure that most proplem for human in the deep soace is X-ray and Gamma ray (that really should be blocked by some mass of material, but not charged particles, so I was wrong :-)
      In same time for charged particle the EM sheilding is the best solution. As alternative idea, I can suppose also to use of some semiconductor diode-like surface that has strong EM field between two p-n layers…

      • Michael C. Fidler March 24, 2018, 10:57

        A Barium shield would work for the X-rays maybe gamma rays. Barium is interesting because of its magic number 137 and its relationship to the fine structure constant and the pions sparking of the vacuum (radioactivity).

    • Michael C. Fidler March 24, 2018, 10:30

      The Plasma Magnet Drive: A Simple, Cheap Drive for the Solar System and Beyond, by Alex Tolley.


      This would be a good system for charged particles but the cosmic rays would need to be ionized by the plasma. (As any good alien would know:-)

      • AlexT March 25, 2018, 10:41

        Yes , it sounds promising.

  • Alex Tolley March 24, 2018, 12:10

    I really like the marrying of photon sails to inflatable habitats for crewed exploration.

    Some comments and questions:
    1. Such a large sail seems beyond our capabilities to build and deploy in the near term. How difficult would it be to develop such a sail, deploy and steer it?
    2. Maybe I missed it, but I don’t see any inclusion of the mass for the power supply. For a NEO trip, solar PV seems appropriate.
    Is the power and mass included in your mass calculations, or does it need to be added?
    3. The food and water supply can be located to act as additional directed shielding.
    4. The mentioned M2P2, or later Plasma Magnet, might be a low mass SEP shield. This should be tested in space to determine its effectiveness as it offers a good solution for charged particle deflection if it works as advertised.
    5. Given the low cost of a FH launch compared to the likely mission costs, is it really necessary to pack all the components and crew in a single launch? It might be better to send up the vehicle first, have the ISS crew ready the vehicle, equip it with the consumables, and test out the life support. Only after which, the crew is launched to rendezvous with the ship for the flight. There are probably other options to reduce risk of failure yet keep costs manageable.
    6. Might there be advantages in ISRU to top up the O2 and even H2O consumables? Even if not, should kit be brought along to test consumables extraction on the target asteroid for future missions and longer duration flights?
    7. Although the Dragon capsule is returned to Earth, how likely is it that the sail and inflatable hab plus equipment could be reused, reducing future mission costs?

    • Greg Matloff March 25, 2018, 8:28

      Dear Alex
      (1) People at NASA and elsewhere have talked about large sails for some time. One could, I think be developed. But crew-assisted unfurlment might be necessary.
      (2) I suspect that Dragon’s solar PV would be adequate.
      (3) All ship masses assumed as shielding.
      (4) M2P2 should most certainly be tested in space. I agree with its critics that it might not be effective for propulsion. But it might very well be a great shield for galactic cosmic rays.
      (5) My initial proposal was for one launch. But a dual launch with crew and Drsgon aboard a Falcon 9, with Earth-orbit rendezvous, might be better. It would not be necessary then to man-rate the Heavy.
      (6) Replenishing O2 and H2O at destination asteroid is great, if possible.
      (7) Why not?? I understand that BEAM’s stay at ISS is to be extended.

      I hope that Elon reads your comments and suggestions!

      • Alex Tolley March 25, 2018, 14:18

        People at NASA and elsewhere have talked about large sails for some time. One could, I think be developed. But crew-assisted unfurlment might be necessary.

        I haven’t seen any proposals for km^2 sized sails, other than as thought experiments, although the abandoned heliogyro sail that JPL proposed for the Halley Comet missions had an area of ~ 0.5 km^2 with 8 panels 7.5 km long!

        With the costs of access to space declining with SpaceX’s rocket developments, and more importantly, increased flight frequency, perhaps it would be worth seriously considering doing experiments in space to study deployment issues of large sails.

        The aerial density of the sail in your OP indicates just 2gm/m^2. This is low even for just the sail material, let alone any booms to unfurl and control the sail. Do you have any details on how you arrived at that figure?

        I suspect that Dragon’s solar PV would be adequate.

        That seems reasonable. The Dragon capsule arrays provide about 2 kw of power. This would then have to be shared with the hab, especially the water recycler. The ISS recycler can process 6000 liters/year – so enough to handle the water intake for the crew. I estimate that it would need just approx. 20W to purify those 6000 liters over a year. O2 recycling would be more power hungry if done as it needs to split CO2 and/or H2O. Depending on how much energy the hab needs. Average American residential electricity use is about 1.25 kw/hr, so the crew of 2-4, with some care and efficient consumption they could live off the Dragon power supply.

        I would really like to see this idea fleshed out in more detail. I suspect the solar sail R&D to get it to the required TRL is the hard part of this proposal.

      • Jens Knudsen March 25, 2018, 14:59

        Hmm.. I hope he reads your suggestions, too ;)#

      • J. Jason Wentworth March 26, 2018, 5:29

        How about a spin-deployed (and rigidized) sail? That would also enable centrifugal artificial gravity to be used (a 1960s Saturn V-launched, *manned* Mars expedition heliogyro sailship propasal [it’s mentioned in Louis Friedman’s 1988 book “Starsailing: Solar Sails and Interstellar Travel”] had 80 blades, with two crew capsules spaced along one blade pair, with an “elevator” between them, to provide 1 g gravity), BUT:

        That was a large-crew mission plan, but a small-crew NEO ship like yours could use a much smaller sail, which need not be a heliogyro. A spinning square (like IKAROS), hexagon, octagon, decagon, or disc sail (using either IKAROS-type variable-albedo LCD panels, mass-shifting, or tilt-able, “pie-slice” blades [like Cosmos-1’s] for steering) would be much lighter than a boom-braced sail, and would package compactly and spin-deploy.

  • Michael March 24, 2018, 15:02

    Nothing stop us from launching stages that can be assembled in space to form a much more powerful multi-stage rocket. We can just add enough stages to suit the mission required and then set off.

    • Greg Matloff March 25, 2018, 8:29

      Dear Michael

      Additional stages simplifies launch but might increase cost. A good cost-benefit study is in order.


  • Tom Mazanec March 24, 2018, 15:20

    If we enter an Eddy Minimum and do not have another Solar Maximum this century, will that throw a monkey wrench into this program?

  • Thucydides March 24, 2018, 23:46

    We have spent decades learning to assemble structures in orbit, so there is no need to muck about thinking about how much mass is left over for a solar sail (or any other thing). The Falcon heavy could launch the main stack and the sail could be sent separately on a Falcon 9 (along with a boatload of extra supplies). Or you could use two Falcon heavies, or however many Falcon 9’s…..

    One you start thinking that way, the permutations become much greater and more flexible

  • Greg Matloff March 25, 2018, 8:31

    Dear Tony

    Not having a Solar Max does not kill interplanetary travel. But it will require more shielding. Once again, maybe M2P2 will save the day!


  • Brett Bellmore March 25, 2018, 13:46

    Isn’t there an issue with the minimum shielding for Solar radiation just converting the cosmic rays into secondary showers that are even more destructive?

    • Jens Knudsen March 25, 2018, 15:03

      I am thinking the cislunar space station will give us the experience we need regarding shielding in near interplanetary space.

    • J. Jason Wentworth March 26, 2018, 5:36

      Yep–the secondaries created by the primaries striking a metal module are less energetic, but there are so many created, and so close to the crew members, that they get “full-body radiation showers.” But…the soft, thick fabric walls of expandable habitat modules contain a lot of carbon, so they provide much better (although still not complete) radiation protection.

      • Brett Bellmore March 26, 2018, 12:43

        Ultimately, I don’t think there’s going to be any substitute for eventually genetically engineering ourselves for better radiation resistance, if we’re ever to become a space dwelling species. But cosmic rays are a real problem from that perspective: While you might genetically engineer repair mechanisms and cancer resistance, as I recall, cosmic ray primaries leave a line of dead cells straight through the body due to their high charge, and it’s been estimated that a round trip to Mars could result in as much as 5% of the cells in your body being killed. And as extended as they are, maybe 20% of critical brain cells could be hit somewhere critical over such a period, and if not killed, at least lose some connectivity.

        Unless we can shield against cosmic rays, long duration space missions will be the sort of thing people do once in their lives, knowing they’ll be significantly compromised for the rest of their lives.

        • James Stilwell March 27, 2018, 9:12

          Another good reason why AI will be visiting the stars and not us…

        • Greg Matloff March 27, 2018, 10:15

          Dear Brett

          Human re-engineering might be the solution. But I would not rule out approaches such sad EM shielding. Hopefully, research will raise superconducting temperature significantly.


  • Charley March 25, 2018, 15:32

    “A disadvantage of SLS is the cost permission and constraints imposed by the current state of the US federal government.”

    cost permission …?? what is that ?

    • Brett Bellmore March 25, 2018, 16:44

      A spell corrected typo for cost inflation, perhaps?

      • J. Jason Wentworth March 26, 2018, 5:43

        I’ve never felt this way about a space vehicle before, but I *almost*–but not quite– hope that the maiden SLS launch fails, and spectacularly, because that would likely kill the NASA budget-eating monster! But at the same time, I would hate to see its exciting payloads (including the lunar CubeSat, and the NEA Scout solar sail probe, go down in flames [solar sails have had enough mission failures already!]). I feel like a psychological hostage here… :-)

        • Alex Tolley March 26, 2018, 10:55

          How committed are these payloads to the SLS? Smaller ones that could be launched by FH might be movable depending on how far they have been designed.

          The cost of SLS launches and flight rates make it an extraordinary white elephant. A real pork-barrel, employment project. If the BFR proves out, then the SLS has no niche left to hide in. In that event, the SLS needs to be canceled, Nasa needs to stop trying to design rockets, and several Nasa groups need to find employment elsewhere.

      • Greg Matloff March 27, 2018, 10:16

        I think so. Sorry for the typo–Greg

    • Mark Zambelli March 29, 2018, 11:41

      I read that as “Cost Per Mission”.

  • Charley March 25, 2018, 15:38

    “… galactic cosmic radiation beyond LEO is reduced by a factor of ~5 above LEO, if missions are conducted during solar maximum.”

    why galactic cosmic radiation reduced by a factor of ~5 during solar maximum ?? why during solar maximum ??

  • Mephane March 26, 2018, 3:22

    > Experiments indicate that the Falcon 9 first stage may eventually be recovered and reused, which promises to greatly reduce the cost of space missions to low Earth orbit (LEO) and beyond.

    I am not sure when this article was written, but as of this comment this is no longer a matter of experiments. About a year ago already a Falcon 9 core was reused for the first time in an actual mission, not just a test flight, and since then several cores have been reflown.

    • Greg Matloff March 27, 2018, 10:18

      Dear Mephane

      It was written for TVIW before reuse became commonplace.–greg

  • david lewis March 26, 2018, 10:55

    Use pygmies for space exploration. The smallest man was under 1 foot and ten inches tall and weighted 32 pounds. Such people would require far less food, water, air, and space, allowing for longer duration trips in more comfort.

    Okay, probably not practical given people of such stature are very rare. Nor, I would assume, would many of them care to be astronauts – at least not enough to run a space program on.

    If the galaxy is full of intelligence species, as some assume, I would image some of them would have people of the above size, and would be cold-blooded as well. To them a Orion style nuclear-pulse starship would be more than enough to carry them in comfort amongst the stars. So, where are they?

    Still, there are pygmies in Africa who might be the best people to fill the role of astronaut and space explorer.

    • ljk March 26, 2018, 12:42

      Engineering the Perfect Astronaut

      Some scientists are thinking about what human space travelers will look like in the future. They might be extra-small and radiation-proof.

      by Antonio Regalado

      April 15, 2017

      At the International Astronautical Congress last September, in Guadalajara, Mexico, Elon Musk convinced many die-hard space engineers he could get a fleet of private rockets filled with thousands of people to Mars.

      Musk’s speech was long on orbits, flight plans, and fuel costs. But it was short on how any of those colonists would survive. In fact, the Mars journey would likely be a dead end. Bathed in radiation and with nothing growing on it, the Red Planet is basically a graveyard.

      Recently, a few scientists have started to explore whether we might be able to do a little better if we created new types of humans more fit for the travails of space travel. That’s right: genetically modified astronauts.

      Let’s be clear. No one is trying to grow an astronaut in a bubbling vat somewhere. But some far-out ideas once relegated to science fiction and TED Talks (here and here) have recently started to take concrete form. Experiments have begun to alter human cells in the lab. Can they be made radiation-proof? Can they be rejiggered to produce their own vitamins and amino acids?

      Full article here:


      To quote:

      Mason thinks that space travel will offer a second, very powerful argument in favor of genetically modifying people. “You can’t send someone to another planet without genetically protecting them if you are able to,” he says. “That would also be unethical.”

      But putting astronauts in the mix might also open the door to “enhancement.” For now, the experts remain dead set against using gene editing to make a child who is smarter or endowed with perfect eyesight. But let’s face it: NASA already “selects” people according to just such criteria, accepting only 14 of 18,300 applicants to its latest class of astronauts.

      Maybe you have seen the movie Gattaca? Only supermen with topped-off genomes are allowed to travel to Titan, while the genetic losers, called “in-valids,” stare up in envy as the rockets lift off. Like most good science fiction, the 1997 film is not so far from reality.

      • Alex Tolley March 26, 2018, 13:59

        There is a long history in SF of modified people to colonize different environments. The most recent I have read are Peter Watts protagonists modified to live in the deep ocean environment. Others have provided technological solutions, like John Varley, or Robert Sawyer.

        While genetic modification could improve an individual’s capability of living in space, it cannot possibly be anything beyond a band-aid. IMO, far more likely at this point are technological solutions to combat or mitigate the environment. They are simpler, more flexible, and ultimately more effective, as biology, particularly mammalian biology, is unsuited to conditions very different from those on Earth.

        • Brett Bellmore March 27, 2018, 6:44

          As a standard issue human, with a standard issue son, I certainly hope unmodified humans have a future in space. But I can’t avoid noticing that a lot of the problems humans face in space are due to details of our biology which might be susceptible to alteration.

          At the dawn of genetic engineering, it was agreed to avoid germ line alterations of humans, because the existing techniques were just too hit and miss to ethically pass on the results to future generations. That ban is falling now, in the face of better techniques.

          I can’t see us passing up the advantages of higher radiation resistance and tolerance for lower gravity, just out of genetic conservatism.

          • ljk March 27, 2018, 10:24

            There are already plenty of megadollar industries devoted to the multiple forms of modification of human beings. If we can also increase human intelligence, endurance, strength, and longevity, there will be plenty of people voluntarily jumping at the chance to be modified in those ways, too. If that means more companies making fortunes in the process, watch how quickly questions of ethics become muddied or just brushed aside outright.

            Be honest: If you could be genetically enhanced to survive all sorts of environments and live for centuries, would you not take the opportunity if offered it?

            • J. Jason Wentworth March 27, 2018, 15:03

              If such a technology could, with sufficient development, enable human beings to become different creatures (other animals) altogether, there are folks, called therians, who would gladly avail themselves of it.

            • Brett Bellmore March 27, 2018, 16:01

              In an instant. My first love, before I got diverted into electrical and then mechanical engineering, was biology. Pity I didn’t stick with it, I’d have graduated at just the right time to be an early genetic engineering pioneer. As it is, I did keep human biology as my second major, so at least I understand the current advances.

              Genetic engineering is starting to be used in humans, and any group that won’t use it will just be left behind, unable to compete. I don’t expect there to be many “wild type” humans around a century from now.

              At the same time, we’re not going to have genetically engineered astronauts available for at least a couple decades, even with non-germ line engineering, so we’re going to have to lick the radiation problem anyway.

              • J. Jason Wentworth March 27, 2018, 19:30

                I am glad that I won’t be around to be in the thick of this “brave new world.” Few technologies that can be beneficial don’t have a downside, and all technologies can be deliberately misused. What makes us *us* is a balance of qualities, and changing the “right” ones, to various extents, could result in beings whom we wouldn’t care to include in the human family, even regardless of their appearance. (I’ve seen the Australian wild cats, which look just like house cats, but would just as soon rip your face off as look at you [think killer bee temperament, but among moggies]).

              • ljk March 29, 2018, 9:35

                In Orion’s Arm, unenhanced humans are called baselines.

                There will probably always be various collections of humans who will never conform to modern changes, just like the Amish. They may be the ones who either opt to leave Earth to colonize other worlds to live the lives they want. Or they may be the ones who “inherit” Sol 3 while the rest of the advanced humanity moves on to the stars.

                This is similar at present to those folks who prefer not to use cell phones and computers. It can be done, but modern life in 21st Century civilization is making that option not only more difficult but also isolating for those who choose not to participate in such technologies. This may not be a deliberate control method by those in power or society as a whole, but it will have similar effects.

          • Alex Tolley March 27, 2018, 14:36

            Somatic modification rather than germline would also confer some benefits, but be restricted to the individual. Somatic modification is in active clinical trials for diseases, and no doubt will be used for non-disease modifications by some individuals. I would not be surprised in the “Overton Window” for cosmetic genetic modification changes within a generation or two if the benefits are clear. From there, it will be a short step to germline modification following the same path – disease elimination, then other enhancements.

  • Charley March 26, 2018, 17:05

    To say that this threaded discussion is disturbing is to, but put a smiley face on it. Genetic modification? Creating new strains of people to be radiation resistant ? I thought that there was a prohibition (as well as a moral argument) to the idea of tinkering with people to make them superior in some fashion or another.
    What happened to that idea ?

    This entire idea of transporting people to other planets to colonize and spread out the human genome is perhaps not necessarily the best use of resources. We should find a way. Instead to stabilize and perhaps reduce the population somewhat on earth so that we can stretch out the habitability of our existence here on this planet, rather than going into deep space to try to colonize other worlds.
    That being said, there is always that argument that men are driven to explore and to go beyond the next hilltop see what’s beyond, but I have a feeling that the universe is going to be a very cold, indifferent, and unfriendly place.

    Even if people do in fact, in-depth colonizing distant star systems. They are going to be in the long term, so different from earthlings that they will have nothing probably in common with their remote ancestors and might as well be considered to be a new type of species. Is that OK with everybody? It’s probably going to have to be OK because that’s probably what’s going to end up happening.

    In so far as making short-term interplanetary missions other planets that may be something which the particular astronauts are just going to have to accept as a risky proposition in exchange for their wanderlust. Who else out there has thought in these terms ?

    • Project Studio March 27, 2018, 5:23

      Yes indeed, the debate ranges from those that see humanity going to the stars, but only through the agency of autonomous probes equipped with artificial intelligence, to those who feel the need a very human presence starts expanding through waves of multi ‘generation’ vessels traveling at relatively slow speeds and becoming temporally, culturally, and perhaps genetically isolated from the rest of the species. One positions is that humanity must establish a solar system infrastructure where a sizable portion of humanity lives and works in space habitats far beyond earth orbit where radiation hazards and ecosystem resource recycling present their challenges. It considers that humanity must expand itself beyond the earth to address existential risk and in from the Fermi paradox suggested imperatives for survival of the only know technological intelligence. It is often cited that humanity living in space would consider to evolve and adapt, and that slow human generation colonists might reach their distant destination only to find it already inhabited by intelligent machines (perhaps acting as ‘nannies’ raising synthetic human embryos) who arose later but arrived quicker. All these considerations are in the mix of the thousands of discussions here.

    • Alex Tolley March 27, 2018, 20:17

      This entire idea of transporting people to other planets to colonize and spread out the human genome is perhaps not necessarily the best use of resources. We should find a way. Instead to stabilize and perhaps reduce the population somewhat on earth so that we can stretch out the habitability of our existence here on this planet, rather than going into deep space to try to colonize other worlds.

      This needn’t be a choice. We can do both. We do need to reduce the Earth’s population, preferably by design and not by a climate and resource-driven cull. We can also start colonizing space, where resources are more accessible and could support a vast population.

      Even if people do in fact, in-depth colonizing distant star systems. They are going to be in the long term, so different from earthlings that they will have nothing probably in common with their remote ancestors and might as well be considered to be a new type of species.

      We are evolving naturally anyway. Almost certainly populations will speciate given enough time. Inhabiting new, different environments will accelerate that evolution. I see nothing unnatural about that. Modern humans coexisted with other hominid species for a long time. We could do so again if we speciate again. Unless we change our ways, that could well lead to wars between human types. We seem to be good at that by finding any differentiating factor between “tribes”, physical or cultural. nevertheless, evolution won’t halt and we will change over time, with isolated populations diverging until they become new species.

    • Antonio March 28, 2018, 8:18

      The genetic-modification-for-space-travel idea is totally non-sense and needless. It’s a solution in search of a problem.

  • Greg Matloff March 27, 2018, 10:23

    Dear Everyone

    Wow!! I am very happy that my little TVIW contribution sparked such interest and so many creative ideas. The only way to expand the terrestrial biosphere beyond Earth is to continue this process! so please stay creative. And try to be optimistic!

    Regards, Greg

  • Charley March 27, 2018, 13:21

    One thing that I wonder about, but I haven’t seen Gregory Matloff seek to address in his presentation above is the question about the use of ballistic capture by some planetary body as an approach to explorations.
    Ballistic Capture in case he is wondering as to what the term refers to is the use of the gravitational attractions of multiple bodies to effect a type of trajectory which you go from a starting point to some ending point, but essentially do so without the use of large amounts of propellant and Delta V to achieve your mission profile. The downside to this particular practice is the fact that it usually takes a considerable amount of time to do the actual mission from your starting point to your capture by your target planet.

    Putting aside for the instant radiation burdens that might be impacted on the crew, has anyone considered this as a viable option for your proposed sail-powered rocket mission model? There are several advantages to doing this, which are too lengthy to get into, but it has to do with redundancy in life support and minimizing propellant usage which could be put to better use. At the planetary body that you ultimately arrive at. Just a thought.

    • J. Jason Wentworth March 28, 2018, 16:46

      Charley, Edward Belbruno (in his 2007 book, “Fly Me to the Moon: An Insider’s Guide to the New Science of Space Travel,” see: http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=Fly+Me+to+the+Moon+by+Edward+Belbruno ) wrote about interstellar low-energy, WSB (Weak Stability Boundary [formerly called “Fuzzy Boundary”]) ballistic capture trajectories for comets exchanged between the Oort Clouds of our Sun and of the Alpha Centauri system, but:

      One would either have to be a unicorn (immortal), or “go frozen,” or as a “seed,” or raise many descendants on-board, and be very patient in order to make such a journey. A typical WSB trajectory escape velocity of 2 km/s (1.24 miles/sec.) would get a comet–perhaps one of Freeman Dyson’s unhurried, human-colonized, “interstellar-diffusing, ‘dandelion trees’-growing comet nuclei”–to the outer reaches of our locally favorite trinary star system (about 100,000 AU from Alpha Centauri A and B) in 645,000 years; I wouldn’t care to play ^that^ many games of cloven-hoof Solitaire (or “Rock-Paper-Alicorn,” with the ship’s computer), and there would also be another problem:

      Because–as Belbruno pointed out–the Alpha Centauri system’s closing velocity with respect to our Sun is about 6 km/s (3.7 miles/sec.), the comet would probably–after picking up more speed falling inward from 100,000 AU–fly through the system and escape out its other side (it would have to be moving at about 1 km/s [0.6 miles/sec.] at that distance in order to be captured), and:

      He added that in open star clusters, where the stars’ velocities are about 1 km/s with respect to each other, comets–and also potentially life-bearing material in them–could be shared between solar systems in open clusters. As Arthur C. Clarke wrote, “Travel to the stars is not difficult, if one is in no particular hurry” (he also noted that if one were–or became–immortal, this would dramatically shrink the size of the universe from a psychological standpoint). If there are intelligent extraterrestrial beings who are immortal, or are *very* long-lived, the long interstellar trip times that frustrate us would be of relatively little importance to them.

  • ljk March 29, 2018, 9:39

    Humans, Machines Enter a New Orbit

    As humans prepare to push off the safe haven of Earth and embark on journeys into deep space, a new generation of explorers is in the making — some of them human, some robotic and some with aspects of both.

    By Daniel Stolte, University Communications

    March 28, 2018

    For almost 20 years, humans have maintained a continuous presence beyond Earth. The International Space Station has provided a habitat where humans can live and work for extended periods of time. Yet, despite having established a permanent base for life in space, terra firma is always in reach — within 254 miles, to be exact. If a crew member were to fall seriously ill, he or she could make the return trip back to Earth in a matter of hours.

    “As soon as you venture beyond low Earth orbit, to go to Mars or even further, bailing out no longer is an option,” says Wolfgang Fink, associate professor and Keonjian Endowed Chair in the UA’s College of Engineering. “You’re on your own.”

    Fink predicts that in the not-too-far future, humans will work side by side with robotic machines, non-human intelligence and smart devices in ways never seen before. Human logic and thinking will be joined by, and complemented by, artificial brains and reasoning algorithms.

    For the first time in history, Fink says, we have reached a level where soon the lines between what is considered “human” and what is considered “artificial” are beginning to blur.


    To quote:

    It might sound like the stuff of sci-fi novels and movies to go from systems monitoring the health of astronauts, pilots, soldiers or athletes to creating some kind of “superhuman.” But in a way, that’s exactly where things are going, according to Fink.

    “There is a critical ethical boundary that needs to be considered,” he says. “Where do you stop helping humanity and enter the realm of the supranatural where nothing is wrong with a human, but you try to go on top of that?

    “Where does the human end, and the machine begin? Should robots have rights? This is what we will run into eventually.”

  • ljk March 29, 2018, 13:09

    In regards to discussions on human versus robotic/AI space exploration, these two very recent Space Review articles on the development of the Manned Orbital Laboratory, or MOL, during the 1960s may lend much to the debates. Plus they make for fascinating reading into a part of the early Space Age that was mostly classified until recently.



    In summation: Humans conducting space reconnaissance during the Cold War became more problematic and expensive as computer and imaging technology improved to make automated spy satellites the logical choice.

    The Soviet Union did go through with their version of MOL in the 1970s called Almaz, aka Salyut 2, 3, and 5. The Soviet authorities also eventually concluded that spy satellites could do a better and cheaper job of keeping tabs on their adversaries.