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Two Takes on the Extraterrestrial Imperative

Topping the list of priorities for the Decadal Survey on Astronomy and Astrophysics 2020 (Astro2020), just released by the National Academy of Sciences, Engineering and Medicine, is the search for extraterrestrial life. Entitled Pathways to Discovery in Astronomy and Astrophysics for the 2020s, the report can be downloaded as a free PDF here. At 614 pages, this is not light reading, but it does represent an overview in which to place continuing work on exoplanet discovery and characterization.

In the language of the report:

“Life on Earth may be the result of a common process, or it may require such an unusual set of circumstances that we are the only living beings within our part of the galaxy, or even in the universe. Either answer is profound. The coming decades will set humanity down a path to determine whether we are alone.”

A ~6 meter diameter space telescope capable of spotting exoplanets 10 billion times fainter than their host stars, thought to be feasible by the 2040s, leads the observatory priorities. As forwarded to me by Centauri Dreams regular John Walker, the survey recommends an instrument covering infrared, optical and ultraviolet wavelengths with high-contrast imaging and spectroscopy. Its goal: Searching for biosignatures in the habitable zone. Cost is estimated at an optimistic $11 billion.

I say ‘optimistic’ because of the cost overruns we’ve seen in past missions, particularly JWST. But perhaps we’re learning how to rein in such problems, according to Joel Bregman (University of Michigan), chair of the AAS Committee on Astronomy and Public Policy. Says Bregman:

“The Astro2020 report recommends a ‘technology development first’ approach in the construction of large missions and projects, both in space and on the ground. This will have a profound effect in the timely development of projects and should help avoid budgets getting out of control.”

Time will tell. It should be noted that a number of powerful telescopes, both ground- and space-based, have been built following the recommendations of earlier decadal surveys, of which this is the seventh.

Suborbital Building Blocks

We’re a long way from the envisioned instrument in terms of both technology and time, but the building blocks are emerging and the characterization of habitable planets is ongoing. What a difference between a flagship level space telescope like the one described by Astro2020 and the small, suborbital instrument slated for launch from the White Sands Missile Range in New Mexico on Nov. 8. SISTINE (Suborbital Imaging Spectrograph for Transition region Irradiance from Nearby Exoplanet host stars) is the second of a series of missions homing in on how the light of a star affects biosignatures on its planets.

False positives will likely bedevil biosignature searches as our technology improves. Principal investigator Kevin France (University of Colorado Boulder) points particularly to ultraviolet levels and their role in breaking down carbon dioxide, which frees oxygen atoms to form molecular oxygen, made of two oxygen atoms, or ozone, made of three. These oxygen levels can easily be mistaken for possible biosignatures. Says France: “If we think we understand a planet’s atmosphere but don’t understand the star it orbits, we’re probably going to get things wrong.”

Image: A sounding rocket launches from the White Sands Missile Range, New Mexico. Credit: NASA/White Sands Missile Range.

It’s a good point considering that early targets for atmospheric biosignatures will be M-dwarf stars. Now consider the early Earth, laden with perhaps 200 times more carbon dioxide than today, its atmosphere likewise augmented with methane and sulfur from volcanic activity in the era not long after its formation. It took molecular oxygen a billion and a half years to emerge as nothing more than a waste product produced during photosynthesis, eventually leading to the Great Oxygenation Event.

Oxygen becomes a biomarker on Earth, but it’s an entirely different question around other stars. M-dwarf stars like Proxima Centauri generate extreme levels of ultraviolet light, making France’s point that simple photochemistry can produce oxygen in the absence of living organisms. Bearing in mind that M-dwarfs make up as many as 80 percent of the stars in the galaxy, we may find ourselves with a number of putative biosignatures that turn out to be a reflection of these abiotic reactions. Aboard the spacecraft is a telescope and a spectrograph that will home in on ultraviolet light from 100 to 160 nanometers, which includes the range known to produce false positive biomarkers. The UV output in this range varies with the mass of the star; thus the need to sample widely.

SISTINE-2’s target is Procyon A. The craft will have a brief window of about five minutes from its estimated altitude of 280 kilometers to observe the star, with the instrument returning by parachute for recovery.

An F-class star larger and hotter than the Sun, Procyon A has no known planets, but what is at stake here is accurate determination of its ultraviolet spectrum. A reference spectrum for F-stars growing out of these observations of Procyon A and incorporating existing data on other F-class stars at X-ray, extreme ultraviolet and visible light is the goal. France says the next SISTINE target will be Alpha Centauri A and B.

Image: A size comparison of main sequence Morgan–Keenan classifications. Main sequence stars are those that fuse hydrogen into helium in their cores. The Morgan–Keenan system shown here classifies stars based on their spectral characteristics. Our Sun is a G-type star. SISTINE-2’s target is Procyon A, an F-type star. Credit: NASA GSFC.

Launch is to be aboard a Black Brant IX sounding rocket. And although it sounds like a small mission, SISTINE-2 will be working at wavelengths the Hubble Space Telescope cannot observe. Likewise, the James Webb Space Telescope will work at visible to mid-infrared wavelengths, making the SISTINE observations useful for frequencies that Webb cannot see. The mission also experiments with new optical coatings and what NASA describes as ‘novel UV detector plates’ for better reflection of extreme UV.

Image: SISTINE’s third mission, to be launched in 2022, will target Alpha Centauri A and B. Here we see the system in optical (main) and X-ray (inset) light. Only the two largest stars, Alpha Cen A and B, are visible. These two stars will be the targets of SISTINE’s third flight. Credit: Zdenek Bardon/NASA/CXC/Univ. of Colorado/T. Ayres et al.


{ 37 comments… add one }
  • Michael Fidler November 5, 2021, 10:29

    For 11 BILLION you could put four of these 20 meter telescopes up!

    Need for Giant Space Telescope To Discover Exoplanets Inspires Lightweight Flexible Holographic Lens.


    This is no pipe dream but a NASA sponsered project that can do both high resolution imaging of exoplanets and high resolutions spectrums.

    • Alex Tolley November 5, 2021, 13:19

      So holograms really do work to create virtual lenses, in this case a Fresnel lens that can focus light as well as separate colors for spectroscopic analysis. I would like to see a demonstration of its optical properties on a thin film/plate and if as good as claimed, then as experimental space telescopes with increasingly large apertures.

      • Wojciech Jacyk November 7, 2021, 17:59

        There were also proposals for membrane telescopes, but I think US Defence Department took over that avenue of research and nothing major has been heard about it since years.


        ”The MOIRE optical space system, being designed by Ball Aerospace and its partners for DARPA, is a gossamer structure featuring a 10 meter diameter membrane optical element at a distance 50 meters away from the spacecraft bus. ”

        “DARPA plans to use membrane optics as part of its Membrane Optical Imager for Real-Time Exploitation (MOIRE) program. The program uses lightweight polymer membranes for a 20-meter (66 ft) foldable plastic orbital telescope capable of seeing a 1-meter (3 ft) object from 36,000 km (22,000 mi) away. Membrane grooves range from 4 to hundreds of micrometers in width.[1]”

        • Michael Fidler November 8, 2021, 8:05

          Dual Use Exoplanet Telescope (DUET) from March 9, 2020.

          1. Executive Summary
          The Dual Use Exoplanet Telescope (DUET) is intended as a follow-up to surveys for exoplanets by making detailed observations of specific extra-solar systems. “Dual use”
          refers to a choice or combination of traditional Doppler shift spectroscopy used to make the first confirmed discoveries of exoplanets 1 and, on the other hand, spectrographic
          analysis of directly observed exoplanets, a type of observation not yet possible.

          Exoplanet discovery missions are coming off the drawing boards faster than other space telescopes. Indirect detection by stellar radial velocity is possible with astrometry. However, Doppler shift from high resolution spectroscopy is not presently being pursued in any embodiment of space telescope known to us. Massive échelle spectrographs used for Doppler from the ground are not space qualified. Direct observation has led to a race for coronagraphy that can handle the 1010 contrast ratio of parent star to its planets. Nearby exoplanets are faint, nominally about 30th magnitude, and their orbits subtend just hundreds of millarcseconds (mas). While transit photometry permits brief partial direct observation of atmospheres (without albedos) during occultations of exoplanets orbiting in line of sight with us, 99% of exoplanets do not occult as seen from Earth.

          In this exoplanet mission context, it is no surprise that space telescopes are seeking larger primary objectives to increase photon collection and angular resolution. “Bigger is better” is a mantra among astronomers. However, mirrors scale up in mass approximately as the cube of their diameter, and the largest and by far the most expensive telescope ever built, JWST at 6.5 meters, cannot equal a growing number of 10 m ground-based telescopes. A quantum leap to 39 meter diameter is now underway with the ELT. Size is not a problem once in orbit, but launch and deployment are constrained by mass.

          DUET addresses spectrographic indirect and direct observation for exoplanet discovery at low aerial spacecraft mass. DUET can serve as the large diameter space telescope sought for exoplanet observatory missions. Our rethinking of telescopy comes from a paradigm shift after four centuries of lens/mirror tradition. We place the burden of photon collection and resolving power on diffractive optics which are both low mass and spectrographic. Our studies 4 have indicated that transmission diffractive optical elements (DOEs) are an alternative allowing new types of coronagraphy, very high resolution spectroscopy, launch mass reduction and in-space assembled telescopes (iSATs).


          Optical space telescope without mirrors.


          A notional space telescope without any mirrors or lenses is being investigated. DUET (Dual Use Exoplanet Telescope)
          has a gossamer membrane annular Gabor Zone Plate primary objective that is flat. Highly chromatic stellar imagery is
          disambiguated in a secondary also made from diffractive elements. The data acquired is intrinsically spectrographic and
          could (1) detect radial velocity below 5 cm/sec and (2) take direct spectra of a systems exoplanets. DUET is intended as
          a follow-up to a survey telescope, THE MOST, being developed in tandem which will identify target stellar systems
          with earth-like exoplanets. DUET observes one star at a time, integrating its light until the exoplanetary system is
          resolved. DUET utilizes a battery of coronographic methods including angular differential imaging, interferometric
          nulling, and phased Fraunhofer line subtraction. The potential performance has been given preliminary laboratory tests
          which are detailed in Conference AS11451-192.


          There is also a video presentation with the link on this page:


          This is what is new in the latest research:

          But while Fresnel holographic optical elements — created by exposing a light-sensitive plastic film to two sources of light at different distances from the film — are not uncommon, existing methods were limited to lenses that could only focus light, rather than separating it into its constituent colors.

          The new method allows the designers to either focus light onto a single point or disperse it into its constituent colors, producing a spectrum of pure colors, said Lin, corresponding author and a Rensselaer professor of physics, applied physics, and astronomy. The method uses two sources of light, positioned very close to one another, which create concentric waves of light that — as they travel toward the film — either build or cancel each other out. This pattern of convergence or interference can be tuned based on the formulas Hsieh developed. It is printed, or “recorded,” onto the film as a holographic image and, depending on how the image is structured, light passing through the holographic optical element is either focused or stretched.

          “We wanted to stretch the light, so that we could separate it into different wavelengths. Any Fresnel lens will stretch the light a little, but not enough,” said Lin, an expert in photonic crystals and nano-photonics. “With our method, we can have super resolution on one end, or super sensitive — with each color separated. When the light is stretched like that, the color is very good, as pure and as vivid as you can get.”

          Experimental realization of a Fresnel hologram as a super spectral resolution optical element.

          In summary, we present the design of an unique annular Fresnel hologram based on the interference of two spherical waves. Through an analytical design, we found that the focal-length of our hologram can be tailored by tuning the radius-of-curvature of the two spherical waves. The grating period of the Fresnel hologram decreases monotonically from the center to the outer region and brings the incoming star-light to focus. Experimentally, we have successfully recorded our Fresnel hologram based on spherically symmetrical waves, with a focal-length by design. Furthermore, we have demonstrated a large on-axis dispersive behavior of an incoming, collimated light wave. This work represents the first successful implementation of a scale model optical system for realizing a telescope Fresnel hologram, which can achieve a spectral dispersion of λ = 440–705 nm over an on-axis distance of 190 mm. Therefore, our proposed DUET can simultaneously perform high resolution spectroscopy, high detection sensitivity and have a low areal mass for space exploration.


  • Alex Tolley November 5, 2021, 10:34

    UV production of O2/O3 is not just a potential false positive. It could become a false negative that masks life that may of may not be producing O2 by photosynthesis.

    My understanding was that we should be looking for gases outside of their reaction equilibria. For example, the presence of both O2 and CH4 in sufficient quantities that are not possible naturally. Would UV emissions produce this disequilibrium or not?

    Our sun emits some UV that results in the O3 layer that protects the surface from UV radiation. But even if that was not the case, water blocks UV allowing life, even photosynthetic life, to live in the oceans. Animals would need protection to emerge onto land, and land plants would either not exist, or develop some protection that still allows the needed wavelengths to reach the cells while either blocking the UV or having sacrificial material which is continually created and any toxic material mopped up.

    If it turned out that aerobic life cannot evolve on planets bathed in high UV radiation, we cannot rule out life constrained to anaerobic metabolism. This may be the metabolism of any life in subsurface oceans of icy moons, although how we could possibly detect such cryptobiology remotely is a problem.

    Ideally we need several orthogonal biosignature measures that will reduce false positives to a minimum, while teasing out the signs of any life on suitable exoplanets.

    • Ron S. November 5, 2021, 14:07

      The presence of abiotic oxygen made me wonder whether animal life could arise sooner than on Earth since there is no need to wait for plant photosynthesis to do the job. Animals would almost certainly still evolve from simpler organism but the rapid availability of high energy fuel might speed the process. An ecology where animals and plants both compete for oxygen would be interesting. Of course the abiotic source will have to be long lived, and I am uncertain of that being likely.

      • Geoffrey Hillend November 5, 2021, 18:46

        The exoplanet mass, size and distance from the Sun, and whether or not it’s in the life belt matters. It can’t be a pressure cooked planet with oxygen which we can eliminate. If the JWST and other new extremely large land based telescopes don’t detect any oxygen in nearby Earth sized exoplanets, then we will know it’s going to take a lot a time to find one, but that does not mean we are alone in the universe, but are only beginning our search to map the spectra of all the exoplanets this side of our galaxy and we don’t yet have the technology to do a fast job of that. We might need more sensitive spectrometers or larger space telescopes with 35 to 100 meter mirrors with the ability to always refueled. Hopefully we won’t have to wait that long. We already looked at the idea that false positives might not hang around long enough or their spectra might be too faint to be detected from Earth with today’s technology. The photolysis of water by UV does not make a lot of oxygen.

        Oxygen was here first which was made by life. There must be some kind of life which uses photosynthesis to make oxygen. When there was enough oxygen, paradoxically the same harmful ultra violet split the common form of molecular oxygen or O2 into two atoms of O1. One atom of O1 plus O1 is O2, molecular oxygen. O2 plus O1 is O3, or ozone. The UV lysed the O2 to built of a thick protect layer of ozone, the ozonosphere which is from 10 kilometers to 65 kilometers with the highest concentration at a height of 30 kilometers. Atmospheres, Barbato and Ayer 1981 , page 8 and 13.

  • Mike Serfas November 5, 2021, 12:10

    The Black Brant 9 seems to go up to about 300 km, most of the way to the altitude (but not the orbital velocity) of the ISS. What will it take for the notion of having an orbital space tether to be viable, which could grab onto rockets like these and fling them out from 5-minute missions into 5-year missions?

  • John walker November 5, 2021, 12:10

    I was so taken aback by the preview of the Decadal recommending an ir/o/uv space telescope for the 2040’s having an aperture of “~6m” that I thought the proofreaders had perhaps forgotten a 1. Alas, the full preliminary report confirmed the 6m goal. Gone the dreams of LUVOIR A or B. Granted that particular proposal was too much to hope for.

    While I can’t fault the steering committee for emphasizing what they term “realistic” proposals, I feel that a 6m instrument is not an ambitious goal for 25 years in the future. Whether with 10 -¹⁰ contrast coronagraph or starshade, a 6m aperture is underwhelming. This particular recommendation seems overly cautious to the point of timidity.

    • Ashley Baldwin November 5, 2021, 14:26

      Medium sized UVOIR, ‘MUVOIR’ telescope.

      LUVOIR B and A ( especially ) were always pipe-dreams . With preliminary fantasy island price tags from an organisation with a track record of very unrealistic and hopelessly optimistic cost estimations. The proposed telescope is a HabEX/LUVOIR A compromise in terms of its goals if not design, in being ( pro exoplanet imaging ) off axis, but with a ( non exoplanet imaging favourable ) segmented as opposed to rigid ( pro exoplanet imaging ) monolithic mirror.

      The JWST like segmentation must help reduce critical development time and costs – fitting within a next gen EELV launcher fairing . Though the much more capable LUVOIR B would still have fit within the SLS Block 2 or Starship fairings.

      They’ve sacrificed the bigger telescope in favour of a fleet of new ‘great observatories’. MUVOIR along with two Probe plus Class telescopes operating in the far IR and X-ray range respectively. Spitzer and Chandra II.

      MUVOIR is to all intents and purposes , Hubble 2.

      Will there be a star-shade though ?

    • Wojciech J November 7, 2021, 18:57

      “I was so taken aback by the preview of the Decadal recommending an ir/o/uv space telescope for the 2040’s having an aperture of “~6m” that I thought the proofreaders had perhaps forgotten a 1. ”

      Quite amusing. By 2040 I believe the ability to transport large payloads to orbit will make these plans obsolete. Either a private company working for university or China will put a larger telescope easily.

      China btw is putting a sort of replacement for Hubble next to their space station. They are getting quite serious on their plans for space exploration.


  • Robin Datta November 5, 2021, 14:33

    Perhaps a board of civilian directors co-chaired by Elon Musk & Jeff Bezos may take publicly funded projects further than the entrenched bureaucracy would and could.

    • henry cordova November 6, 2021, 8:55

      Then again, perhaps Messrs Musk and Bezos might hijack these efforts and morph them into profitable tourism schemes, space mortuary businesses, or orbital marketing/advertising platforms.

      I agree that involvement of the private sector in space exploration is a worthwhile goal. Private enterprise has also benefitted mightily from technologies (navigation, remote sensing, communications) pioneered by taxpayer investment. The resources and talents of private business have always manufactured and operated our space missions, even if under the supervision of government. But I am suspicious of this modern obsession that entrepreneurial personalities and institutions are intrinsically preferable to public efforts. NASA, the European Space Agency, and other government agencies, for all their problems and contradictions, have been the true agents of space exploration, particularly in the scientific theater of operations; not the trendy tycoons and hobbyists of Heinleinian fantasy. Space belongs to the scientists and engineers, not the business majors.

      There is a place for the private sector, perhaps even an essential role, but it is not the magic bullet cure-all its proponents seem to think it is.

      • Patient Observer November 7, 2021, 13:07

        The car company Tesla was started by others and taken over by Musk. Musk’s other concepts (Hyperloop, Neural Link, the Boring Company, Solar City, battery powered VTOL supersonic passenger jets, etc.) are ravings of a publicity-seeking self-styled messiah. SpaceX is pretty good but was largely guided and funded by NASA.

        Private enterprise has a place but as noted above. It is not particularly adept at pioneering technology. Don’t count on Musk for anything other than more publicity-seeking to pump up his ego and the stock price of Tesla. BTW, I just purchased a Mustang Mach e. It is better in every way than the equivalent Tesla models. I wonder how long it will take before the Tesla stock bubble bursts.

      • Robin Datta November 7, 2021, 19:35

        The bloats of government bureaucracies, corporate bureaucracies, political nomenklatura and their bureaucracies, the battalions of lobbyist and the hordes of constituents will have to be fed at government troughs.
        These accessory and superfluous opportunistic feeders should be cheerfully accommodated.

    • Tiens van Greuning November 6, 2021, 19:37

      Messrs Bezos and Branson’s efforts seems useful in terms of getting the public at large excited about space. The PR value of sending James T Kirk to space can not be underestimated.

      Messr Musk, on the other hand, is an engineer who can not only find solutions to engineering problems which people with established thought patterns will never solve, but he also has the ability to identify and hire people who may or may not have gotten their education through the traditional channels, but who themselves can cut through problems and instead of compromises, find the win-win.

      His engineers has already dropped the cost of access to space considerably, and forced established rocket companies to start innovating or die. If Starship proves successful, it will be a total game changer to everything we are talking and dreaming about in these pages.

      Some of these people he hires, leaves his company after a few years and start companies of their own, spreading this win-win mindset even further.

      Musk’s engineers are also driving innovation in electric vehicles, solar panels and battery technology. And don’t overlook the innovation in manufacturing processes to drive down costs of these. And anywhere off-planet, you’ll be needing electric vehicles, solar panels and batteries.

      Now if you want to look for evidence of ET life, you should also look in our own back yard. On the Moon for a start.

      Without messr Musk’s efforts, the return to the Moon might establish an orbital outpost and some exploration missions to the surface, even a base on the Moon itself. But the going will not be fast and come at a prohibitive cost, so odds are that it may fizzle out at some stage.

      Cutting the coat of getting heavy things to Luna, though, may enable us to do a lot more than just explore a bit.

      One might now find some other billionaire emerging, who can make a business case for establishing mining operations and manufacturing plants on the Moon.

      Maybe we will see some truly huge telescopes being built on the Moon. You could conceivably also launch very large telescopes into space from there in one piece, as it doesn’t have to fit into any type of fairing for getting through Earth’s thick atmosphere, and the launch could be considerably more gentle than a launch from Earth.

      You could also imagine, if you can build a rocket like Starship on the Moon and manufacture the fuel it needs there, what kind of missions become possible because you only need a fifth of the Delta V to achive escape velocity from the Earth Moon system if you launch from there. Even a smaller rocket, with a large Ion drive 2nd stage and a huge tank full of propellant, will enable even more ambitious missions.

      Some aspiring billionaire may seize the opportunity to establish mining and manufacturing operations on a near earth asteroid, dropping escape velocity requirements and launch stress to virtually zero. You could conceivably build and launch a kilometer diameter telescope in one piece to 500AU from an asteroid if you were so inclined.

      You could also, very far away from any humans that may come to harm, build and test nuclear type propulsion technologies instead of just dreaming about them. Or build and test huge solar sails. Or huge space lasers to propel sails with…

      Maybe the next generation will not have to wait another generation to see some great things happen.

      • charlie November 8, 2021, 16:44

        “Messr Musk, on the other hand, is an engineer … ”

        In 1990, Musk entered Queen’s University in Kingston, Ontario.[31][32] Two years later, he transferred to the University of Pennsylvania; he graduated in 1997 with a Bachelor of Science degree in economics and a Bachelor of Arts degree in physics.[33][34][35]

        In 1994, Musk held two internships in Silicon Valley during the summer: at energy storage startup Pinnacle Research Institute, which researched electrolytic ultracapacitors for energy storage, and at the Palo Alto-based startup Rocket Science Games.[36] In 1995, Musk was accepted to a Doctor of Philosophy (Ph.D.) program in materials science at Stanford University in California.[37] Musk attempted to get a job at Netscape but never received a response to his inquiries.[26] He dropped out of Stanford after two days, deciding instead to join the Internet boom and launch an Internet startup.[38]

        • Patient Observer November 8, 2021, 21:45

          Let’s dig deeper into the Musk myth.


          The relevance here is that the SpaceX Starship will lead human spaceflight, at least for US humans, to a dead end. Supporting information to that claim can be found on the YouTube link provided above. It will be difficult to view by those enamored with the Shinny Future offered by the Rocket Jesus or it will be denied with fire and fury.

          Agreed that NASA is hobbled by politicians and lobbyists working for private companies and has made stupid decisions by abandoning much of its competency to said private companies.

          • Alex Tolley November 9, 2021, 11:13

            Pt 1 and 2 are just the usual hit pieces. Musk may or may not be the worst self-promoer, but there are plenty of others in Silicon Valley. I’ve worked for one, and almost everyone I knew had similar tales to tell of CEOs. Tech CEOs always want to remain the lead tech person – note Bill Gates and his behavior. Sales/Marketing CEO Steve Jobs was an exception, but he was renowned for his :reality distortion field”. Yet under his guidance, twice, Apple became a great company, while other CEOs – Sculley, Spindler, drove it into the ground under their respective reigns.

            The more interesting piece in on the Mars version of Starship. Some very good points are made, although the explanations for the apparent anomalies are easily constructed.. But remember the skeptic team used a promo video from a company that was not part of the SpaceX team. Despite being posted in February this year, it still shows the WWII bomber/Dan Dare Spacefleet style glass canopies that have disappeared in the versions now shown. At one point the skeptics rightfully explain the need for cooling panels, yet later suggest that a storage compartment will be too cold. Hmmm. As for the sleeping berths, well those old slave ships come to mind. ;)

            I think it is pretty clear that Musk/SpaceX has hyped the Mars deal, much as governments once hyped colonial conditions, and parodied by P K Dick in his many stories (“A new life awaits you in the off-world colonies, a chance to begin again in a golden land of opportunity and adventure.”).

            Whatever one thinks of Musk and SpaceX, they did create reusable rocket launchers and drove down launch prices, forcing the industry to follow along. Unlike the reusable Space Shuttle, the costs really did come down. Starship has yet to fly, but Nasa has chosen a Moon version for the Artemis program. Unless you think Nasa has been bamboozled, coopted by know-nothing corrupt pols, or it is a conspiracy to blow up SpaceX when it fails, the reality is that SpaceX is building what will be a huge, fully reusable launcher and spaceship. It may end up as a mostly empty tin can, best suited for cargo rather than people, but then so be it. SpaceX can always use the proven Falcon 9 and Crew Dragon capsules for crew transport.

            The relevance here is that the SpaceX Starship will lead human spaceflight, at least for US humans, to a dead end.

            That is your opinion with no facts to support it, given that you are predicting an unknowable future. Starship as a transporter to aid the Mars Society vision of Mars colonization may be the wrong model, just as the Mars Society has been pushing for ever more hyped rosy scenes of Mars colonization. In the very long run it may prove true, just as who could have predicted the USA of today at the time of the Jamestown colony? Even China has failed to instantly build shiny cities in its west full of happy populations, but don’t doubt that eventually they will work assuming the planet doesn’t become unlivable first.

            • Gary Wilson November 10, 2021, 15:42

              There do seem to be a lot of quirks and possibly altered history to Elon Musk’s personal life and relationships to past businesses. However whether he actually produces the key engineering concepts for SpaceX and Tesla or not,the two companies are vital as far as I can see. Tesla is producing an excellent product (electric cars) which are moving us away from CO2 producing internal combustion engines as well as other types of batteries for energy storage. We will have problems in the future related to our handling of rare earth elements that will require changes to the way the mining and processing is done (much of it is done with no regard to environmental damage in China) but these cars are part of a future which does not rely on carbon emissions. As for SpaceX, whoever is actually doing the engineering, I think it’s obvious that the rockets being produced have lowered launch costs, are successful (the first stage landings for reuse are real) and do transfer both cargo and humans to ISS. These are undeniable facts. As for Starship, the future is unclear but the ideas seem revolutionary. I really couldn’t care less if Musk is a self-promoting narcissist. The companies he has set up are doing vital work. Sad to say NASA is a giant pork barrel with SLS as the biggest piece of pork of all. What a tremendous waste of American taxpayer dollars. Look at the launch costs projected for SLS and the projected cargo cost per pound to orbit and you will see the sad truth. Compare it to Falcon and the rest of the SpaceX rocket designs.

              • Patient Observer November 14, 2021, 13:49

                Too much to make a full rebuttal. All prediction of the future are opinions so I accept that criticism. SpaceX promised drastic reduction in launch costs yet they have yet to materialize even with reused boosters. The cost of a seat on the Dragon capsule is, what, $50 million? DOd and NASA pay top dollar for a SpaceX launch. StarLink will make a nice meteor shower someday. I see that there was not rebuttal to the air-head stupidity of the batter-powered VTOL SST, the boring company, the Hyperloop, etc. Tesla makes a good car (not the best in my opinion). I am intimately familiar with tech CEOs and have seen narcissists who do a damn good job at faking. Enough said.

  • Afterthought November 6, 2021, 8:10

    If a goodly chunk of the explored universe is without life can we really say the universe is “fine tuned” for life?

    • Alex Tolley November 6, 2021, 11:21

      Perhaps better to say “fine tuned for terrestrial life, or life as we know it”. The physics constants impact a lot of things, any deviation of which can cause the universe to fail to work as it does. If there is only one universe, the anthropic principle is the strongest argument for a designing intelligence, IMO. This has led to the idea that there is a multiverse, with universes of different constants being born (and dying) with only a vanishingly small being stable like our universe.

      I I was writing the code to create stable universes, rather than testing the unimaginably vast space all value combinations, I would “evolve” a universe whose objective function was to be stable and create life. Our universe may be the best so far, or the parent of some future or parallel universe that is even more biophilic and stable.

    • Abelard Lindsey November 7, 2021, 15:28

      That’s a good point and one that the promulgators of which completely ignore for what I think are ideological reasons. If our universe is, indeed, optimized for organic life, it is reasonable to believe that habitable planets are quite common and that alien civilizations exist as well. If we really are alone, then it makes no sense to claim that the universe is “fine tuned” for organic life.

      • Hamilton1 November 8, 2021, 10:38

        Then again, if we are alone, that doesn’t make any sense either.

    • Patient Observer November 14, 2021, 15:25

      We can say that the universe is fine-tuned for chemistry. The life part is a bridge too far

  • ljk November 7, 2021, 0:16

    Guess who might be the first organic passengers from Earth on humanity’s first interstellar missions…


    After all…


  • Henry Cordova November 7, 2021, 10:22

    I’m all in favor of investing big bucks in astronomical research, and big telescopes in space will certainly pay big dividends–as far as basic research is concerned.

    But we should resist the urge to spend enormous amounts of money on narrow research interests. As important as SETI and astrobiology are, to devote large sums to that effort alone is a big mistake. Big expenditures on specific questions are unavoidably going to deprive other, equally important research projects. If we are going to devote large sums to basic research, the instruments should be as multi-purpose and generalized as possible, so that all branches of the science can potentially benefit.

    This debate is a lot like the old ‘basic vs applied’ research debate. As critical as the big questions in astrobiology are, we should not lavish resources on them that might otherwise help other research interests. After all, we have no guarantee that these big astrobiology missions will actually answer any fundamental questions. And even if they do, those answers may not actually be applicable to our understanding of the universe in general.

    Yes, we need more and bigger ‘scopes, but they should not be too highly specialized for one specific purpose. In the long run, all the really big breakthroughs have always come from basic, not applied, research programs.

  • Kevin in WI November 7, 2021, 17:52

    We are on the cusp over the next 10-20yrs of seeing launch costs seeing a further 20x reduction in cost Per kg to orbit. The primary goal of a telescope capable of resolving habitable zone planets is laudable, But we should consider the changing orbital economics. The timeline and total cost would likely improve if we erred on the side of larger size, proven systems, possible multiple launch/orbital assembly and periodic servicing, in lieu of designing the absolutely most capable telescope that can fit in a weight optimized/single launch/never serviced platform.

    • Henry Cordova November 8, 2021, 12:04

      “We must yield to the logic of the situation.” LCDR Spock, SF, UFP

      There will always be more worthwhile targets than there are possible sorties. And we will take casualties in every mission.

      We have to prioritize.

  • ljk November 8, 2021, 14:00

    How To Announce the Discovery of Extraterrestrial Life (and Be Taken Seriously)

    Proposed new guidelines could be helpful, or they could be a form of scientific censorship.

    By Dirk Schulze-Makuch




    I wonder how many people, both public and professionals, realize the terrestrial value and power of being the one to detect an ETI? So many of us science-minded folks are naturally dazzled by the science and the knowledge that may be gained from such a discovery, yet there are plenty of other humans on this planet who, when they do take aliens seriously if they haven’t already, will want to get in on whatever technology and power these beings may possess. If they are part of a larger galactic community, you can rest assure the human in power on the Pale Blue Dot will want in on it.

    You can be shocked and saddened by such seemingly mundane and narrow visions, but that is the reality on this planet. And don’t be at all shocked if more than a few scientists and academics are thinking of how being the ones to reveal the first genuine ETIs will set them for life economically, socially, and in human history.

    I know the Chinese recognize all this: They made no bones whatsoever about their new and huge FAST radio telescope conducting SETI as one of their primary scientific objectives.

    Meanwhile, back when Arecibo was still in one piece, the folks in charge at the time wanted to keep any mention of aliens at arms length. Same for the Green Bank Radio Observatory, where Project Ozma was the first modern era SETI effort. Their radio telescopes are still intact and they have since figured out that the days of aliens equaling peer shame are largely gone: Now they give tours showing where Frank Drake first tried to detect aliens circling Tau Ceti in 1960!

  • DCM November 9, 2021, 16:52

    I wonder if difficulty for us finding them lies in really advanced aliens being able to give their atmosphere the appearance of being hostile to life.

  • ljk November 11, 2021, 13:55


    [Submitted on 1 Nov 2021]

    A Search for Analogs of KIC 8462852 (Boyajian’s Star): A Second List of Candidates

    Edward G. Schmidt

    In data from the Kepler mission, the normal F3V star KIC 8462852 (Boyajian’s star) was observed to exhibit infrequent dips in brightness that have not been satisfactorily explained.

    A previous paper reported the first results of a search for other similar stars in a limited region of the sky around the Kepler field.

    This paper expands on that search to cover the entire sky between declinations of +22 degrees and +68 degrees. Fifteen new candidates with low rates of dipping, referred to as “slow dippers” in Paper I, have been identified. The dippers occupy a limited region of the HR diagram and an apparent clustering in space is found. This latter feature suggests that these stars are attractive targets for SETI searches.

    Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

    Cite as: arXiv:2111.01208 [astro-ph.SR]
    (or arXiv:2111.01208v1 [astro-ph.SR] for this version)

    Submission history

    From: Edward Schmidt [view email]

    [v1] Mon, 1 Nov 2021 19:02:55 UTC (86 KB)


  • Gary Wilson November 14, 2021, 18:37

    Thanks for the link ljk. A very interesting read. It’s far too soon to make any predictions as to whether this clumping of dipper stars is real but very interesting. The P value isn’t great as the author mentions but is suggestive of a real clump of odd stars. Lots of work to do here including SETI. I hope we can turn something important and significant up. If they are aliens they are a long way away from us, which might be just as well as they must be extremely advanced.

    • ljk November 16, 2021, 11:54

      You are welcome, Gary.

      When the nature of Tabby’s Star was revealed by Kepler, I pointed out the following in this blog several times:

      That it was found in such a narrow region of the sky says one of two things: Either we got extremely lucky finding such an apparently rare celestial object, or there are a lot more of them than we realize.

      In the event Tabby and its brethren are not a natural cosmic phenomenon, might this mean we are inside a Kardashev Type 2 or 3 galaxy? Would we even know if we were, or believe it, until the construction crews are almost literally on our doorstep?

      If it is natural, the fact that we cannot come up with a completely good fit in terms of relevant theories shows we are either still quite ignorant of the workings of the Universe, or something else is going on.

  • ljk November 16, 2021, 17:06

    Chipping away at some of the more extreme “natural” explanations for Oumuamua – which artists in these news items still refuse to show as as a flat disk, based on the data…


  • ljk November 16, 2021, 17:09

    Fifty years ago, Mariner 9 became the first probe to orbit Mars. This robotic vessel literally changed our views of our neighboring globe.

    Mariner 9 is supposed to crash on the Red Planet sometime in 2022 – which once seemed so far in the future.


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