Existential risks, as discussed here yesterday, seem to be all around us, from the dangers of large impactors to technologies running out of control and super-volcanoes that can cripple our civilization. We humans tend to defer thinking on large-scale risks while tightly focusing on personal risk. Even the recent events near Chelyabinsk, while highlighting the potential danger of falling objects, also produced a lot of fatalistic commentary, on the lines of ‘if it’s going to happen, there’s nothing we can do about it.’ Some media outlets did better than others with this.
Risk to individuals is understandably more vivid. When Apollo 8 left Earth orbit for the Moon in 1968, the sense of danger was palpable. After all, these astronauts were leaving an orbital regime that we were beginning to understand and were, by the hour, widening the distance between themselves and our planet. But even Apollo 8 operated within a sequenced framework of events. Through Mercury to Gemini and Apollo, we were building technologies one step at a time that all led to a common goal. No one denied the dangers faced by every crew that eventually went to the Moon, but technologies were being tested and refined as the missions continued.
Inspiration Mars is proposing something that on balance feels different. As described in yesterday’s news conference (see Millionaire plans to send couple to Mars in 2018. Is that realistic? for more), the mission would be a flyby, using a free return trajectory rather than braking into Martian orbit. The trip would last 501 days and would be undertaken by a man and a woman, probably a middle-aged married couple. Jonathan Clark, formerly of NASA and now chief medical officer for Inspiration Mars, addresses the question of risk head-on: “The real issue here is understanding the risk in an informed capacity – the crew would understand that, the team supporting them would understand that.” Multi-millionaire Dennis Tito, a one-time space tourist who heads up Inspiration Mars, says the mission will launch in 2018.
Image: A manned Mars flyby may just be doable. But is the 2018 date pushing us too hard? Image credit: NASA/JPL.
We’ll hear still more about all this when the results of a mission-feasibility study are presented next weekend at the 2013 IEEE Aerospace Conference in Montana. Given the questions raised by pushing a schedule this tightly, there will be much to consider. Do we have time to create a reliable spacecraft that can offer not only 600 cubic feet of living space but another 600 for cargo, presumably a SpaceX Dragon capsule mated to a Bigelow inflatable module? Are we ready to expose a crew to interplanetary radiation hazards without further experience with the needed shielding strategies? And what of the heat shield and its ability to protect the crew during high-speed re-entry at velocities in the range of 50,000 kilometers per hour?
For that matter, what about Falcon Heavy, the launch vehicle discussed in the feasibility analysis Inspiration Mars has produced for the conference? This is a rocket that has yet to fly.
No, this doesn’t feel much like Apollo 8. It really feels closer to the early days of aviation, when attention converged on crossing the Atlantic non-stop and pilots like Rene Fonck, Richard Byrd, Charles Nungesser and Charles Lindbergh queued up for the attempt. As with Inspiration Mars, these were privately funded attempts, in this case designed to win the Orteig Prize ($25,000), though for the pilots involved it was the accomplishment more than the paycheck that mattered. Given the problems of engine reliability at the time, it took a breakthrough technology — the Wright J-5C Whirlwind engine — to get Lindbergh and subsequent flights across.
Inspiration Mars is looking to sell media rights and sponsorships as part of the fund-raising package for the upcoming mission, which is already being heavily backed by Tito. I’m wondering if there is a breakthrough technology equivalent to the J-5C to help this mission along, because everything I read about it makes it appear suicidal. The 2018 date is forced by a favorable alignment between Mars and the Earth that will not recur until 2031, so the haste is understandable. The idea is just the kind of daring, improbable stunt that fires the imagination and forces sudden changes in perspective, and of course I wish it well. But count me a serious skeptic on the question of whether this mission will be ready to fly on the appointed date.
And if it’s not? I like the realism in the concluding remarks of the feasibility study:
A manned Mars free-return mission is a useful precursor mission to other planned Mars missions. It will develop and demonstrate many critical technologies and capabilities needed for manned Mars orbit and landing missions. The technology and other capabilities needed for this mission are needed for any future manned Mars missions. Investments in pursuing this development now would not be wasted even if this mission were to miss its launch date.
Exactly so, and there would be much development in the interim. The study goes on:
Although the next opportunity after this mission wouldn’t be for about another 13 years, any subsequent manned Mars mission would benefit from the ECLSS [Environmental Control and Life Support System], TPS [Thermal Protection System], and other preparation done for this mission. In fact, often by developing technology early lessons are learned that can reduce overall program costs. Working on this mission will also be a means to train the skilled workforce needed for the future manned Mars missions.
These are all good reasons for proceeding, leaving the 2018 date as a high-risk, long-shot option. While Inspiration Mars talks to potential partners in the aerospace industry and moves ahead with an eye on adapting near-Earth technologies for the mission, a whiff of the old space race is in the air. “If we don’t fly in 2018, the next low-hanging fruit is in ’31. We’d better have our crew trained to recognize other flags,” Tito is saying. “They’re going to be out there.”
In 1968, faced with a deadline within the decade, NASA had to make a decision on risk that was monumental — Dennis Tito reminded us at the news conference that Apollo 8 came only a year after the first test launch of the Saturn 5. Can 2018 become as tangible a deadline as 1970 was for a nation obsessed with a Moon landing before that year? If so, the technologies just might be ready, and someone is going to have to make a white-knuckle decision about the lives of two astronauts. If Inspiration Mars can get us to that point, that decision won’t come easy, but whoever makes it may want to keep the words of Seneca in mind: “It is not because things are difficult that we dare not venture. It is because we dare not venture that they are difficult.”
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@James Jason Wentworth,
There was a discussion on VASMIR here a while ago. I found this talk by Zubrin on Youtube :
Politics in his talk aside, he was very skeptical about VASMIR for Mars. In a nutshell, once you take into account the mass of the nuclear reactor necessary to power it and all the cooling radiators, it wasn’t very convenient.
Putting radiation risks into perspective:
Exposure for a Mars trip and return: 500-1000 mSv (milli Sieverts)
Chronic high dose, but presumably nowhere near fatal dose: 800 mSv/a on a Brazilian beach
100 mSv acute dose -> 0.8% cancer risk increase [USA EPA acute dose level estimated to increase cancer risk 0.8%]
500 mSv/a USA NRC occupational whole skin, limb skin, or single organ exposure limit (IOW a safe limit that is comparable to the mars flyby dosage).
So what we have, if the data is reasonably correctly, is a likely small increase in lifetime cancer rate, or dose within lifetime limits.
So our crew is going to trade a small increased cancer risk for a lot of glory (assuming they don’t get hit by a CME en route). That has to be a lot safer than many occupations, including sports like boxing.
An extreme event may well kill you, but skill or luck in avoidance of such an event will not. So this doesn’t appear to be the bogeyman that is being suggested.
So if these data are in the ballpark, the crew will likely have more of a problem with their hardware and psychological stress than with the radiation hazard.
Time for those stating that radiation is a severe hazard state their data and assumptions that show that radiation hazard is so severe that massive shielding or very fast trips are needed. At this point radiation from the solar wind and cosmic rays doesn’t seem to be a show stopper, even without any shielding, let alone some water shielding to reduce their effects.
GaryChurch wrote (in part):
“I apologize for posting three times in a row but I become perplexed when so many comments are made that drive me to again comment on these analogies. Space is not an ocean. You will not survive a solar event like you might survive a storm at sea. It is completely different. It is not a valid comparison in any sense including length of mission.”
Then we should just…give up. Many younger people seem quite content to “live” in virtual computer-generated worlds that allow simulated missions to anywhere in the cosmos rather than actually visiting other worlds, so maybe it won’t matter anyway. Also:
If robotic means for “mining away” (or moving) potentially hazardous asteroids are developed, we can just stay on Earth (except for occasional low Earth orbit excursions). Since the yearly odds of Earth being struck by a long-period comet or being disastrously orbitally perturbed by a rogue planet are very small (and since the end of the Sun’s benign phase is so far off), a long future for humanity–provided that self-inflicted destruction can be avoided–appears likely. But it doesn’t sound like a very interesting or inspiring future…
“So our crew is going to trade a small increased cancer risk for a lot of glory (assuming they don’t get hit by a CME en route).”
You cannot assume that. Remember the solar telescope on Skylab? Why do you think they made it our first space station’s primary instrument? You keep forgetting Apollo 17; they missed dying of radiation exposure by two weeks.
You cannot just hand wave this away and trust in whatever numbers you come up with that say you might survive.
Bear in mind that Russians performed Mars500 experiment which is exactly Dennis Tito’s Inspiration Mars flight might be. There are already hard data available and Russians would be not doubt interested in the real experiment plus the results of their mock flight.
As I haven’t seen yet papers on Mars500 results there are plenty of videos of the project – http://www.youtube.com/user/Mars5OO/videos?view=0
Regarding radiation hazart you should bear in mind on Earth there are plenty of habitable zone w/ high background radiation and people are willingly habitating them. Higher than the Fukushima exclusion zone radiation.
– You’re using MARIE data for radiation exposure near Mars… yet MARIE was knocked out by solar radiation at least a couple of times (and is apparently no longer operational).
While a 500 day mission has very high but survivable radiation exposure (with some eye opening peaks – take a look at a couple of years of MARIE data), the cosmic ray damage to organs cannot be hidden by averaging the radiation exposure. Those heavy particles can cause permanent damage when they slam into eye, brain or nerve tissue. The effects of long term exposure to GCRs can vary but it’s unlikely that the exposure will confer super powers.
A couple of relevant papers:
(this one is based on MARIE data)
From the above paper- ” In contrast median REID (Risk of Exposure Induced Death) values for Mars mission scenarios exceed the NASA limits in most scenarios and the upper 95% confidence level often exceeds 10% REID”
The real danger is a solar event. Unless you know the exact timetable for a solar proton event or CME, you’ll be playing a game of Russian Roulette. A solar event on day 499 may be survivable, since you’re days from medical care. One on day 30 may not be.
Then again, repeatedly stating categorically that normal radiation levels in space are intolerable does not make it so. Many years of actual exposure prove you wrong.
A lightly protected vehicle with a more strongly protected small shelter for CMEs is the right approach and will work quite well. Your “14 feet” is a gigantic red herring. CME is low energy radiation, and a few inches of aluminum, plastic, or water will do wonders. Energetic cosmic rays are exceedingly sparse and do not have to be shielded against.
@FrankH – thank you for the papers. The Cucinotta paper is particularly good.
So my take home from this is:
Even the conservative NASA guidelines suggest that the proposed Mars mission would not be a show stopper due to GCR exposure. Older individuals and some shielding (10 cm of water) reduces the risk of subsequent death from cancer considerably.
I thought that CME’s were the big problem, but this paper suggests that the GCR problem is greater, especially for long missions. Rapp indicates that 10 cm of water a good shield for both GCR and solar events. So going with 10 cm, that is 1/10 tonne per m^2. So 10 tonnes of water could provide 100 m^2, or a sphere shelter with a diameter of 5.5 meters and 700 m^3 of living volume – larger than Bigelow’s BA 330 inflatable hab. This doesn’t seem unreasonable for the mission, trading off a risk of higher cancer rates for a chance of entering the history books.
“Then we should just…give up.”
We can do it; it just means the defense industry will have to be persuaded to earn some hard money for a change instead of all the easy money they have been enjoying building cold war toys.
It will take a HLV launch ten times a year for up to 20 years; then nuclear powered and propelled spaceships will begin launching from a Moonbase. You want to play you gotta pay, or as I like to say,
There is no cheap.
Why HLV if we can hafe space lift? A Japanes company already announced they intend to build by 2050. Country which build first space lift will have 80% of space launch market share. Pretty lucrative considering the current trend are small, CubeSAT size sattelites, which is affordable for many countries and organizations.
Russians have calculated for safety reasons their nuclear powered propulsion engines should be ignited in orbit at 800 – 1000 km.
Well to correct myself:
1) The only company who plans to build HLV is SpaceX which will be Grasshopper-type (up-back-ready-in-2-hours).
2) Roskosmos and NASA both are making plans for post ISS era. It’s lifetime expires at 2020, which might be extended 2023-2025 but that’s it.
3) Roskosmos and NASA pushing on developments on VASIMR propulsion and at least Roskosmoses announced first test fligth at 2018. 2009 Russians talked openly on co-operating w/ NASA on nuclear propulsion development as interplanetary cosmos is a bit too expensive for a nation to venture alone. Don’t know in which state it is.
4) After Fobos-Grunt disaster Roskosmos reassessed their shortcomings and aknowledge they will take first the Moon, then manned mission to Moon and after that only to Mars to test new technology and platforms and to raise from ashes the former glory of space engineering and the industry. That’s why the currently under developement space vehicle “Rus” is Moon landing capable, which NASA’s Orion is not by design because NASA’s plan is to have a manned landing on an asteroid in 2025 – 2030.
4) NASA plan is go to Mars the earliest 2032. Roskosmos says close to 2040. SpaceX clearly indicate technology necessary for their commercial Mars roundtrips will take 12-30 years to develop (2025 – 2043).
They are so in ballpark that there is no sign of HLV except private sector – read SpaceX. 2015 is Lunar X Prize deadline which means someone in the private sector will do the move. Even space elevator is feasiable and real competitor considering the timeline.
Just based on facts there is difficulties to fit your vision of HLV.
“Even space elevator is feasiable and real competitor-”
Never saw a space elevator that didn’t work.
If a Heavenly Funicular (space elevator) from the Earth’s surface to space can be built (material of the required strength is within sight, and lunar, martian, and asteroidal space elevators are practical *now*, with existing fibers), it will be a game-changer, making it possible to very cheaply lift components of interplanetary spaceships–radiation shielding and all–into geosynchronous orbit. True, the Earth space elevator will be very expensive, but since it will be more akin to a civil engineering project like a bridge, its cost can be amortized over many years by many users, since it will make trips to and from space (for everything from comsats to lunar journeys to voyages to other planets and to asteroids) so much cheaper that the amount of space traffic will increase tremendously. Also:
In fact, some studies indicate (as Arthur C. Clarke was excited to read) that with space elevators and rotating tethers, travel throughout the solar system could eventually become nearly as cheap as travel on Earth. Between these unorthodox space transportation methods (including electromagnetic launchers on the Moon and asteroids, plus solar sails and electric rockets), as well as nuclear thermal & solar thermal rockets (with fusion rockets becoming practical later on), we will have plenty of choices for fast and slow interplanetary transportation of people, active payloads, and cargo. Building a literal bridge to space (the space elevator) will enable all of these possibilities, but:
It is *not* necessary to wait for an Earth space elevator to become feasible in order to begin building this transportation (and lunar and planetary base) infrastructure. Reusable launch vehicles like those that SpaceX and Blue Origin are developing could establish a financially-viable, if not ideal, first rung on the Earth-to-space “ladder.” The next rung–the Moon–could be established using the lunar space elevator that the LiftPort Group is developing. Their self-deploying lunar space elevator, which will pass through the Earth-Moon L1 Lagrangian point (where a depot could be established), could be delivered to the Moon by a single SpaceX Falcon 9 rocket. From there (once industrial operations are set up on the Moon), the Mars system could be added to the interplanetary transportation network in a similar manner.
“Your “14 feet” is a gigantic red herring.”
Equals the protection of the Earths air column at 18,000 feet above sea level.
I do not think Eugene Parker would agree with you. He is pretty famous in some circles. I will go with his recommendations, thanks anyway.
GaryChurch: You would do well to look at this paper previously recommended by Alex Tolley: http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf
Here are some excerpts:
This is already not nearly as bad as your grizzly assessments (seething with radiation, etc). Further, consider 1) “95% CI” means, to be absolutely sure, we assume the radiation is 3-4 times as much as it is actually expected to be. So, actually, the dose is below allowable limits. 2) “allowable annual dose” means that your projected risk of dying of cancer is 3% higher, i.e. goes from ~30% to ~33%. Less dangerous than, for example, a habit of smoking, skydiving or frequent swimming.
So much for your Apollo 17 astronauts narrowly escaping “being killed”.
As I have been saying….
At last, now I understand your thinking. Your assumption being that the highest levels on earth humans live is the tolerable safe radiation limit. But this is indeed a red herring. The 18000 ft limit is a oxygenation limit (and close to a fire limit too), but has nothing to do with safe radiation limits. We have independent studies that show it is far higher. Our DNA repair mechanisms are quite good, although nowhere near as good as other organisms.
One suggestion I found quite counter intuitive is that it may be better to travel during solar max rather than min. This is because the SPEs can be shielded quite easily (unlike GCR), but that GCR intensity falls (The Forbush effect).
So can we start to put Battlestar Galactica type ships to rest for the near future and focus on smaller, cheaper spacecraft for inner system flight?
Here is a comprehensive list, courtesy of Beyond Apollo by David S. F. Portree, of manned Mars flyby mission plans past and present:
“Your assumption being that the highest levels on earth humans live is the tolerable safe radiation limit. But this is indeed a red herring. The 18000 ft limit is a oxygenation limit (and close to a fire limit too), but has nothing to do with safe radiation limits.”
14 feet of water is what will stop the heavy nuclei without generating secondary radiation. It just so happens to equal the protection of Earth’s air column above you if you were at 18,000 feet.
400 rems and the 1972 astronauts (if they had been caught in the august storm) would have to have had complete blood changes to survive that dose.
The ISS recieves only half the GCR as a crew in deep space- they have shielding on the station that generates some secondary but it is better than taking a larger dose every 90 minutes as the station passes through the mid atlantic anomaly.
“Based on a 2001 study of cancer patients undergoing radiation therapy and epidemiological studies of the atomic bomb survivors, Cucinotta has calculated that the added cancer risk of a 1,000-day Mars mission in an aluminum spacecraft, which would shield half the cosmic rays encountered, falls between one and 19 percent. A one percent increase is a risk most people would find acceptable. But taking the highest risk number and adding that to an astronaut’s normal incidence of getting cancer (20 percent) results in a whopping cancer risk of 39 percent.
Cucinotta’s best guess estimate is that without extra hydrogen shielding, Mars missions of 660 and 1,000 days would push 40-year-old astronauts over the NCRP risk thresholds.”
39% huh. Getting close to a coin toss.
LiftPort fundraising on Kickstarter reminded HyperV (http://phys.org/news/2012-11-plasma-jet-thrusters-kickstart-interplanetary.html) try to raise money. I was surprised that public interest into such type investment is so high despite palpable results being away for a quite good time. In this sense we are on brink of an era where small money can do big things for space industry as the cost goes down and suitable platforms become more available – nao-sat, Android-sat etc.
Estonia will launch its first sattelite ever based on Cube-Sat platform – ESTCube1 which launch costs €64 000. It’s small money in terms of cosmos but big money in terms of fixed costs. Cube-Sat platform seems to go big way as more and more are utilizing its possibilities. If the cost of launch would go down more countries and enterprises would enter into space industry.
When talking about Earth space elevator constantly comes back Russian’s other intention w/ nuclear propulsion – tug-satellites. If they would have had thug-satellite available on Earth’s orbit they would have saved the Fobos-Grunt space craft, fixed it and on second try send to its mission. At the moment there is no available technology to correct the trajectory once you are in space and made a mistake. The tug-satellite armada would solve this kind of errors – grab the craft and put on the right orbit.
Now regarding heavy lifters and chemical propulsion. This is something recalled the other day. Russians have long sought for analogous ammuniton as is America’s MOAB (Mother Of All Bombs). In 2007 they achieved the goal by doing first areal test drop of their bomb – news clip of this http://www.youtube.com/watch?v=rXzp-JOrDf0. They nicknamed the bomb DOAB (Daddy Of All Bombs). They achieved yield of 44 tons compared to MOAB’s 11 tons by modifying on nano scale the chemical component they don’t disclose. Only bit of information in the clip that it’s w/ higher yield than TNT. MOAB contains 8,2 ton of explosives against DOAD 7,1 ton. In last 6 years there has been significant advances in chemical and nano field and I have not heard of chemical propulsion rockets using any new advanced nano-scale tweaked one. There might be quite good chances for heavy or very heav load a new type of chemicals mix might be used.
Reaching Earth’s lower orbit takes 8-15 minutes. To dock w/ another craft it takes 2-3 days. It was just the last launch of Soyz craft which made the experimental approach to ISS from start to docking in 6 hours. Earth space elevator would reach orbit (22 000 km and higher) in 7.3 days doing 200 km/h. There is a viable bussiness niche for VHL, Earth space elevators and other means of launch i.e. Virgin Galactic White Knight method.
[Here is a comprehensive list, courtesy of Beyond Apollo by David S. F. Portree, of manned Mars flyby mission plans past and present:
Thank you! I’d seen that before but couldn’t remember the site’s (or its authors’) name. Those proposed crewed planetary flyby missions were referred to as “space station missions that actually *go* somewhere.”
Dmitri wrote (in part):
[Now regarding heavy lifters and chemical propulsion. This is something recalled the other day. Russians have long sought for analogous ammuniton as is America’s MOAB (Mother Of All Bombs). In 2007 they achieved the goal by doing first areal test drop of their bomb – news clip of this http://www.youtube.com/watch?v=rXzp-JOrDf0. They nicknamed the bomb DOAB (Daddy Of All Bombs). They achieved yield of 44 tons compared to MOAB’s 11 tons by modifying on nano scale the chemical component they don’t disclose. Only bit of information in the clip that it’s w/ higher yield than TNT. MOAB contains 8,2 ton of explosives against DOAD 7,1 ton. In last 6 years there has been significant advances in chemical and nano field and I have not heard of chemical propulsion rockets using any new advanced nano-scale tweaked one. There might be quite good chances for heavy or very heav load a new type of chemicals mix might be used.]
In the 1950s, Professor Fritz Zwicky advocated vigorous research into (molecular) “fragment chemistry” in order to develop chemical rocket propellants of much higher energy content than LOX/LH2. I think Arthur C. Clarke was referring to the same thing when he wrote in “The Promise of Space”: “It is just possible that the chemists may produce weird, meta-stable substances, not occurring in nature, which can provide more energy than existing propellants, but it would be foolish to count on it.” The inventors of the DOAB may have achieved just what Fritz Zwicky advocated.
These Apollo hardware planetary flyby missions also included Venus, which actually attracted *more* attention than Mars in these studies because Venus’ nearly-circular orbit ensured regular minimum-energy launch windows. Reading through the Venus flyby mission studies, I found that the higher radiation levels nearer the Sun were a concern but were not considered a “show-stopper.” Richard Tongue covers these proposed missions in his book “One False Step…” Also:
Below I have included URLs to articles and documents about these proposed Venus, Mars, Venus/Mars, and even dual Venus/Mars crewed flyby missions (including one *2011* proposal for such a Venus flyby mission); they are:
Crewed Venus flyby missions:
Crewed Mars flyby missions:
Crewed Mars *and* Venus flyby missions
James Jason Wentworth said on March 8, 2013 at 0:13:
“Thank you! I’d seen that before but couldn’t remember the site’s (or its authors’) name. Those proposed crewed planetary flyby missions were referred to as “space station missions that actually *go* somewhere.”
Maybe someone will by the ISS when it is time to retire it and use for a manned lunar or Mars mission. Better than dumping it in the ocean as has happened to every space station before it, deliberately or otherwise.
For those who will now pounce on the idea of using the ISS as a manned vessel to other worlds just to bring it down, do your homework first before squashing it. We got megatons of space hardware up there which I would hate to see go to waste.
Eh, the Chinese will probably take it over in the end to add to their growing space empire.
A Martian adventure for inspiration, not commercialization
Last week, a new organization founded by a pioneering space tourist announced plans for a crewed Mars flyby mission to launch in 2018. Jeff Foust describes the background of the mission and the various challenges to turn this unique concept into an actual voyage.
Monday, March 4, 2013
The future of the US human spaceflight program is not reliving its past
Civil space policy, in particular human spaceflight, was not an issue in last year’s presidential election. Roger Handberg argues that space advocates must stop believing that the president restore the agency to the glory years of the 1960s but instead focus on what’s needed to create a more sustainable program for the future.
Monday, March 4, 2013
ljk wrote (in part):
[Maybe someone will by the ISS when it is time to retire it and use for a manned lunar or Mars mission. Better than dumping it in the ocean as has happened to every space station before it, deliberately or otherwise.]
…And it need not be reused for that just *once* (and thank you for your two new links!). Re-fitting the ISS after its retirement, re-naming it “Mars Cycler Aldrin,” and boosting it into a meta-stable (with regard to regular Earth flybys) two-year solar orbit would give us the first way station to the Mars system. Also:
In his book “Mining the Sky,” Dr. John S. Lewis discussed re-building near-Earth asteroids in similar orbits to create ~800 meter “tall” Cyclers (each with a 1 g, rotating Earth gravity wheel at its “waist”) that could comfortably house 220,000 passengers. To maintain a meta-stable relationship with Earth, small solar thermal rocket engines (“fueled” with water obtained from the excavated asteroidal rock) would be fired from time to time. In addition:
Before creating such “Queen Mary Squared” Cyclers becomes practical, smaller Cyclers (such as a re-purposed ISS and Bigelow-type stations) can be used to get this interplanetary infrastructure up and running. Cyclers would “mesh” well with other non-rocket space transportation systems such as rotating tethers, space elevators, and electromagnetic launchers, requiring only low-powered thrusters on the cargo/passenger modules to make the final, small velocity-matching maneuvers.
“Queen Mary Squared” Cyclers are really the best of all possible worlds. But I have to respectfully point out the larger a pulse propelled spaceship becomes, the easier everything becomes in terms of bomb performance.
Manufactured-on-the-Moon-titanium discs several thousand feet in diameter would efficiently absorb the pulse from larger and more efficient bomb designs. Launched from the low lunar gravity, An air filled torus inside a moon water filled shield torus would be mounted on shock absorbing struts on the inner surface and the huge disc spun to provide earth level radiation and artificial gravity.
The real beauty of this approach is to make use of a vast store of classified weapons design data.
Untrue. Perhaps you did not read far enough to catch the following excerpts from your citation?
It is time to come to your senses.
Note that the above is without ANY shielding, and that shielding against CME is easy. As of the same (your) citation:
“Heavily shielded”. The ISS. No 14 feet, here…
A worthless argument from authority, and mistaken to boot. I believe Eugene Parker is far more reasonable about this than you are. You should reread that Scientific American article and point to a place where he actually says that 14 feet are necessary to protect astronauts. Necessary to reduce even the most energetic GCR to zero, yes. But that is NOT required, and unlike you, Dr. Parker does not claim it is.
“Necessary to reduce even the most energetic GCR to zero, yes. But that is NOT required,-”
Actually, it does not really reduce it to zero because of the secondary radiation that is seeping through. But it is equivalent to 18,000 feet above sea level.
I strongly believe that radiation exposure will be the biggest problem of all for astronauts on long duration missions and for colonists; they will be getting plenty of exposure anytime they leave the shield area unless a huge transfer device is available. Any EVA will bump up there lifetime exposure number closer to the limit. We have already seen this with Shuttle Astronauts hiding their dosimeters in the least irradiated area of the Orbiter while on missions instead of wearing them.
Flying around in a jetpack or bunny hopping are all good fun but for a person with a lifetime dose limit, it is the seconds of a career ticking away.
And the ISS has heavy shielding against normal space radiation encountered when passing through the mid atlantic anomaly- this radiation shielding actually generates more secondary radiation because of heavy nuclei but it ends up being less than they would get from going through the anomaly without it.
I think you are still making red herrings and also shifting the goalposts. The 18000 ft level of radiation is irrelevant to tolerable human exposure. I thought that was explained already. Goal post shifting, because now you are generalizing to multiple trips and deep space flight (e.g. outer system). All we are talking about in this thread is a single, 500 day trip to Mars. Your prediction is that the radiation exposure will make the trip unsurvivable, UNLESS, the craft is extremely heavily, and impracticably, shielded. The evidence so far is that you are exaggerating the threat for this mission.
[“Queen Mary Squared” Cyclers are really the best of all possible worlds. But I have to respectfully point out the larger a pulse propelled spaceship becomes, the easier everything becomes in terms of bomb performance.]
Such a 0.8 km asteroid Cycler that could accommodate 220,000 passengers would *be* a world (albeit a small one), to me at least. Dr. Lewis’ discussion of such Cyclers in “Mining the Sky” even mentioned them being able to transport (and provide life support for) as many as *one million* passengers, although in crowded, unhealthy “cattle car/steerage”-type conditions.
[Manufactured-on-the-Moon-titanium discs several thousand feet in diameter would efficiently absorb the pulse from larger and more efficient bomb designs. Launched from the low lunar gravity, An air filled torus inside a moon water filled shield torus would be mounted on shock absorbing struts on the inner surface and the huge disc spun to provide earth level radiation and artificial gravity.]
Doing this will require extraterrestrial (*independent* lunarian) governmental jurisdiction, because it is simply not legally possible on Earth (or at an Earth-controlled lunar settlement, if there was one) today due to the Nuclear Test Ban Treaty–and remember, even “mere” launch vehicles powered by storable hypergolic (read: toxic, carcinogenic, and mutagenic) propellants are being phased out, so any project involving A-bombs has a very tall public relations barrier to climb over. I’m not saying that it can’t *ever* be done, but with the current prevalent attitudes, only a China or (maybe) a North Korea could pull off such an achievement today, because their governments don’t have to care about what their citizens think. And:
[The real beauty of this approach is to make use of a vast store of classified weapons design data.]
I wouldn’t count on that data *ever* becoming public domain…but fortunately, “open” design work was done on the Orion pulse charges; Dyson’s team came up with a nuclear charge design that was a (very) short-life rocket. It was a cylindrical chamber with a de Laval convergent-divergent rocket nozzle on the end that would face the Orion spaceship’s pusher plate, with the bomb in the far end. Between the bomb and the nozzle was a thick cylinder of polyethylene plastic, which would be vaporized by the bomb and be further accelerated (as well as aimed) by the nozzle to strike the pusher plate, in the unicorn’s eye-blink instant before the whole charge unit was vaporized. They calculated that these directional nuclear charges would enable the pusher plate to intercept 50% of the bomb debris, which would enable smaller nuclear explosive devices to be used.
[Note that the above is without ANY shielding, and that shielding against CME is easy. As of the same (your [GaryChurch’s]) citation:
Astronauts on the International Space Station (ISS), by the way, were safe. The ISS is heavily shielded, plus the station orbits Earth inside our planet’s protective magnetic field. “The crew probably absorbed no more than 1 rem,” says Cucinotta.
“Heavily shielded”. The ISS. No 14 feet, here…]
Having worn a lead-filled plastic “blanket” during dental X-Ray photography sessions, I wonder if a lead-lined work & sleep garment (something resembling “hoodie-footie pajamas”) would be helpful to keep the total absorbed radiation dose lower (not necessarily a strong solar flare dose, but the incessant little ‘click,’ ‘click,’ ‘click’ dose that adds up slowly, day after day during an interplanetary mission)? While the immune system does have built-in defenses for dealing with slowly-accumulating radiation doses (as health physicists discovered during the NB-36 nuclear reactor-carrying airplane project in the 1950s), such a garment might remove that “workload” from spaceship crews’ immune systems. Also:
Certain foods help the body fight off the effects of radiation, and they could be included in the ships’ pantries. In addition to blueberries and billberries (bilberries?), which are rich in anti-oxidants, Miso (a fermented soy or soy & rice paste) has also been found to help the body fight the effects of radiation. And:
It is a general immune system booster, and it also acts as a chelating agent. Interest in Miso for its anti-radiation effects began after the atomic bombs fell on Japan. Aid workers who went into the bomb-affected areas of (Nagasaki, if memory serves) developed radiation sickness, *except* for one group of aid workers who operated from a Seventh-Day Adventist hospital on the outskirts of town, which had survived the blast. Curious doctors, who wondered why that group of aid workers did not develop radiation sickness, found that those aid workers were fed large amounts of Miso soup at the hospital, and further research showed that it had protected them from the effects of the radiation via chelation and boosting their immune systems.
“I’m not saying that it can’t *ever* be done, but with the current prevalent attitudes, only a China or (maybe) a North Korea could pull off such an achievement today, because their governments don’t have to care about what their citizens think.”
I disagree for 3 reasons John,
First, the only other time we dedicated a meaningul percentage of public funds to space exploration was in response to a threat from the now defunct Soviet Union. We have a new threat now in the form of comet and asteroid impacts and a possible bioterror extinction level event. Protecting humankind from extinction holds the penultimate moral high ground concerning tax dollars.
Second, the nuclear treaty requires signatories to agree on using nuclear devices outside the Earth’s atmosphere; they will agree. All the nuclear activists on Earth will not be able to argue with a plan to save Earth from what is essentially the nuclear weapon effects of impacts. The SLS has a human-rated capsule and a very powerful escape system and there is no better vehicle for transporting weapon “pits” safely to the Moon.
Third, while America will have the rocket, international support will provide the supply of bomb material. There is a great deal of plutonium sitting around in nuclear plants all over the world waiting to be processed (Japan alone has 40 tons in storage). International fleets of Atomic Spaceships will be no more expensive than nuclear missile submarines and armored divisions; every nation will want a Spaceship or at least some representative crewmembers to help defend the Earth.
“All we are talking about in this thread is a single, 500 day trip to Mars. Your prediction is that the radiation exposure will make the trip unsurvivable,-”
Sorry, I was talking about a Spaceship capable of long duration beyond Earth and lunar orbit human space flight. And they might survive- and they might not. Which means that sending humans instead of a robot is a really stupid idea.
“The 18000 ft level of radiation is irrelevant to tolerable human exposure.”
I am sorry you cannot understand the 18,000 ft benchmark. I will try a third time to explain the relevance;
When a heavy nuclei hits matter it fragments the matter it hits into secondary radiation that is extremely damaging. When penetrating matter at some point the heavy nuclei cannot penetrate the mass and distance. The 14 feet of water is the point at which heavy nuclei in deep space stop penetrating a shield completely and also stop generating high levels of secondary. Some secondary (equal to standing on an 18,000 ft mountain) still seeps through even a massive 14 ft thick water shield.
You want to send humans into deep space Alex? First answer the question of why.
If it is to intercept an impact threat to Earth with nuclear weapons then having some humans present would be advisable.
If it is to start a survival colony where a population is self-sufficient and capable of restarting the human race in the event of an extinction event on Earth like an engineered pathogen, then yes, absolutely.
But to send two people on a joy ride? No. Absolutely not.
GaryChurch wrote (in part):
[First, the only other time we dedicated a meaningul percentage of public funds to space exploration was in response to a threat from the now defunct Soviet Union. We have a new threat now in the form of comet and asteroid impacts and a possible bioterror extinction level event. Protecting humankind from extinction holds the penultimate moral high ground concerning tax dollars. ]
I very much want to be wrong–and want you to be right–concerning this, but I don’t think any nuclear (and especially nuclear bomb) propulsion system for asteroid tug ships will get the green light unless we get the astronomical equivalent of hitting a mule over the head with a 2 X 4 just to get his attention: An Arizona meteor(ite) crater-like, major impact event that wipes out thousands of people and leaves a glowing, smoking hole in the ground. As the visually-spectacular but (thankfully!) non-lethal Chelyabinsk fireball event recedes into the past, people and governments are going back to business as usual, thinking “It’s just a one-in-million chance–nothing worth spending more money on.”
Let me again explain this very patiently, again: The heavy nuclei you are so concerned about are so rare that without any shielding they produce nothing more than a slight to moderate occupational hazard. Comparable with and less than many other, much more dangerous occupations. The only real health threat is that of a massive solar storm. Early warning plus a few inches of shielding can completely take care of that.
We are getting closer to the truth, now. “They will die” has been replaced by “they will eventually run into their lifetime exposure limit”. Note that this a conservative regulatory limit grounded in an abundance of caution, not in any real evidence that lifetime exposure at low levels of radiation has a cumulative health impact.
NASA’s Gemini Program: a “stepping stone” to Mars?
The space community has debated various precursor missions for a human Mars expedition, including trips to the Moon and near Earth asteroids. Harley Thronson notes, however, that these proposals are in sharp contrast the Gemini program, a precursor to Apollo driven entirely by what was needed to support the ultimate goal of landing humans on the Moon.
Monday, March 25, 2013
The uneasy state of NASA’s human space exploration program
Next week marks the third anniversary of President Obama’s speech calling for a human mission to an asteroid, but many people, including some within NASA, still have trouble accepting that goal. Jeff Foust reports on that perceived lack of enthusiasm and whether a new proposal to retrieve an asteroid could change people’s minds.
Monday, April 8, 2013
For NASA, the planetoids and Mars are in, the Moon is out. Will it get only better or worse when the next Administration comes along in 2016? Remember what happened to the Constellation program.
Top 10 Weirdest Mars Illusions and Pareidolia
Ever since Italian astronomer Giovanni Schiaparelli described his discovery of canals on Mars in 1877 and American astronomer Percival Lowell started to map …
Things To Do During a Piloted Venus/Mars/Venus Flyby Mission (1968)
By David S. F. Portree
06.15.13 at 3:14 AM
From 1962 to 1967, NASA and its contractors studied piloted Mars/Venus flybys as a possible interim step between Apollo lunar missions in the 1960s and piloted Mars landing missions in the 1980s. Many of the conceptual flyby spacecraft designs were based on planned or proposed Apollo and Apollo Applications Program technology.
Starting in February 1967, the flyby concept fell into disfavor following criticism by the President’s Science Advisory Committee (PSAC). President Lyndon Johnson’s PSAC, which had previously supported the piloted flyby concept, declared that piloted flybys made unnecessary use of astronauts, and that NASA should reassess its plans for the application of humans and robots in space. NASA substituted the word “encounter” for “flyby” and continued to task Bellcomm, its Washington, DC-based Apollo planning contractor, with studies of various aspects of piloted flyby missions.
In August 1967, however, Congress eliminated all funds for piloted flyby studies and other advanced mission planning from the Fiscal Year 1968 NASA budget. The lethal AS-204/Apollo 1 fire was a key factor in the decision to cut funding designed to give NASA a post-Apollo future.
Writing in the aftermath of these cuts, Bellcomm cautioned that its February 1968 report on experiments and observations to be conducted during a 1977 Venus-Mars-Venus encounter mission “should be considered as illustrative of feasibility rather than a plan for the future.”
Full article here:
Cosmonaut Valentina Tereshkova; 1st Woman in Space 50 Years Ago! Ready for Mars
by Ken Kremer on June 16, 2013
50 Years ago today, Soviet Cosmonaut Valentina Tereshkova made history and became the first woman ever fly in space, when she launched aboard the Vostok-6 capsule on June 16, 1963.
The then 26 year old Tereshkova blasted off from the Baikonur Cosmodrome – following in the historic footsteps of Cosmonaut Yuri Gagarin, the first human to fly in space for a single orbit in 1961.
Her mission was far longer, lasting nearly 3 days (70 hours 50 minutes) for a total of 48 orbits of Earth at altitudes ranging from 180 to 230 kilometers (110 x 144 mi). She conducted biomedical & science experiments to learn about the effects of space on the human body, took photographs that helped identify aerosols in the atmosphere and manually piloted the ship.
“Hey, sky! Take off your hat, I’m coming!” she said in the seconds prior to liftoff.
Vostok-6 was her only space mission.
But today at age 76, Tereshkova is ready to forget retirement and sign up for a truly grand space adventure – a trip to Mars.
“I am ready [to go to Mars],” she said in remarks on the occasion of the 50th anniversary of her June 16, 1963 blastoff, according to Roscosmos, the Russian Federal Space Agency. Apparently Mars is her favorite planet!
“Of course, it’s a dream to go to Mars and find out whether there was life there or not,” Tereshkova said. “If there was, then why did it die out? What sort of catastrophe happened?”
Full article here:
Private enterprise plans for Mars: