[HN Gopher] The case for building a SETI observatory on the moon
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The case for building a SETI observatory on the moon
Author : pseudolus
Score : 136 points
Date : 2020-10-03 10:14 UTC (12 hours ago)
(HTM) web link (www.supercluster.com)
(TXT) w3m dump (www.supercluster.com)
| feralimal wrote:
| Good idea! 1972 was so long ago...
| koheripbal wrote:
| Why does it need to be physically ON any planetary body? What are
| the advantages of having it on the moon rather than free floating
| in a moon-like orbit? ...or for that matter a more distant
| eccentric orbit?
| koheripbal wrote:
| I should have read the article... the answer is shielding. even
| in lunar orbit, it's better than orbiting the Earth for brief
| periods.
| jcims wrote:
| For large aperture radio-telescopes like Arecibo or VLBA one
| advantage would be that you can use gravity and the structural
| reinforcement of the surface to maintain precise formation and
| location of your reflectors.
|
| One of these days we'll perfect fine stationkeeping and be able
| to fly large clusters of scopes/reflectors/etc and surface-
| based scopes will likely become less attractive.
| Rebelgecko wrote:
| Thermal management is easier when you can physically touch
| other objects, easier to know where you are, easier to maintain
| pointing accuracy, etc
| jvanderbot wrote:
| Size also. It's easy to spool dish wires out on the ground on
| the moon, hard to spool them out and keep them where you want
| in orbit.
| a1369209993 wrote:
| > hard to spool them out and keep them where you want in
| orbit.
|
| Well, it's easy if you rotate the whole thing and use
| centrifugal force, but that has other problems.
| pueblito wrote:
| One advantage would be a foothold on a strategically valuable
| location
| whimsicalism wrote:
| Democracies are far too short-sighted for this to be an
| actual reason. Also, this is just a paper published in a
| journal.
| screye wrote:
| Space brothers did it first
| 7373737373 wrote:
| A while ago I read an article about which properties signals
| might have that could indicate that they originated from
| intelligent life, something about having "acceleration", higher
| order derivatives, that are usually not generated by natural
| events. Does anyone know how this is called?
| poma88 wrote:
| I will change fields to use tha data and find life out there!!
| :-)
| wazoox wrote:
| It should be made in the form of a black monolith, I guess. Just
| for the kick.
| ieatmyownpoop wrote:
| Ah yes. The death star.
| jagged-chisel wrote:
| But it's a _moon_ , not a space station.
| skadamou wrote:
| _That 's no moon_
| dang wrote:
| Trollish usernames aren't allowed on HN because they
| effectively troll every thread they post to. I've banned the
| account, and would be happy to rename and unban it if you want
| to pick a more neutral username. Best to email
| hn@ycombinator.com if that's the case.
|
| https://hn.algolia.com/?query=by:dang%20trollish%20username&...
| tgflynn wrote:
| I'm fed up with titles like this that suggest that an entire
| scientific community, or at least some body with a legitimate
| claim to representing the interests of that community, wants
| something when all that is really happening is that some
| particular group of scientists has submitted a proposal.
|
| Here's the first line of the article:
|
| > On Monday, a group of researchers sponsored by Breakthrough
| Listen, the world's largest program, submitted a paper to
| National Academy of Sciences' Planetary Science and Astrobiology
| Decadal Survey that makes the case for establishing a SETI radio
| observatory on the farside of the moon.
|
| Note that this line is also incorrect due to a missing word.
| Breakthrough Listen may be the world's largest SETI program, but
| it is certainly not the world's largest program, whatever that
| would even mean.
|
| So this is some particular group of SETI specialists, which I
| highly doubt represents the interests of the astronomical
| community at large (I would guess that only a small fraction of
| astronomers even work on SETI).
|
| Don't get me wrong, I'm not criticizing the project itself, just
| the misleading title of the article and the general decline in
| journalistic standards.
| arbuge wrote:
| I think these concerns would be addressed by adding a single
| word to the title. "Some", at the beginning.
| tgflynn wrote:
| I think a more accurate title would be something like:
|
| SETI Project Proposes Building an Observatory on the Moon
| majkinetor wrote:
| Stop with this millennial shenanigans already.
|
| NOT everything needs to be predigested so that you save 3
| seconds of your time.
|
| Article is fine, title is fine, you are the ones that need
| to change.
| dredmorbius wrote:
| Quite, yes.
| dredmorbius wrote:
| NB: https://www.supercluster.com/editorial/the-case-for-
| building...
|
| Title: The Case for Building a SETI Observatory on the Moon
| dredmorbius wrote:
| Fair point. It's a bait-and-switch, motte-and-bailey
| equivocation tactic: on casual reading, the bailey is that "all
| astronomers', or a majority, or some authoritative generally
| representational body speaking authoritatively, is making a
| claim. The motte is that those making the claim _are_
| astronomers.
|
| https://rationalwiki.org/wiki/Motte_and_bailey
|
| The harm is greater in that we're used to headlines
| referencing, say, public opinion (majority or at least
| plurality of a population), organisations (official
| spokesperson as opposed to some arbitrary worker or
| whistleblower), etc.
|
| It's a cheap shot. All the more so because it seeks to borrow
| from the greater reputation and fame of the larger group,
| admitting by deed the obscurity of the actual group in
| question.
|
| "SETI Group Wants to Build Radio Observatory on Moon" avoids
| all these problems here.
|
| Addendum:
|
| The article originally appeared with the title "The Case for
| Building a Seti Observatory on the Moon" here:
|
| https://www.supercluster.com/editorial/the-case-for-building...
| JoeAltmaier wrote:
| Not worth the emotional investment. Of course "some" is
| assumed. And isn't it more correct to talk about who wrote the
| paper, than which organization published it?
| tgflynn wrote:
| > Of course "some" is assumed.
|
| That's not how it initially parses for me, and I think for
| most people.
|
| As for the emotional investment, for this one case certainly
| not, but this same pattern keeps coming up time and time
| again, not to mention the constant barrage of other
| nonsensical statements the media constantly exposes us to. I
| think this incessant stream of micro-aggressions against
| logic and common sense ends up having a significant impact on
| our well-being and at a larger scale may even be contributing
| to extremism, conspiracy theories and the growing absence of
| any semblance of truth from the ambient political discourse.
|
| > And isn't it more correct to talk about who wrote the
| paper, than which organization published it?
|
| I'm not sure what you mean by that.
| dredmorbius wrote:
| Link and title have just been changed from
| https://www.smithsonianmag.com/science-nature/why-astronomer...
| dang wrote:
| The submitted title was "Astronomers Want to Build a SETI
| Observatory on the Moon" which came from the submitted URL
| (https://www.smithsonianmag.com/science-nature/why-
| astronomer...). I think you're reading it with the wrong
| quantifier: to me the claim is not "[all] astronomers want
| [etc.]" but "[some] astronomers want [etc.]", which is
| perfectly reasonable.
|
| But it's fine to change a title when it's landing the wrong way
| with some readers, and it seemed like there was a better link
| in this case, so a mod changed both the URL and title.
| dmos62 wrote:
| Hacker News readers are fed up with inaccurate generalizations.
| tambourine_man wrote:
| Any observatory for that matter. I keep dreaming of humongous
| mirrors, easily accessible, with no clouds or atmosphere to get
| in the way. Or, you know, moon. Imagine what we would discover.
|
| I fell like we neglect the moon to a embarrassing degree. It's
| right there (cosmologically speaking), it's got water, plenty of
| sun light (24/7 even, on the pole), building materials... what
| are we waiting for?
| Already__Taken wrote:
| it builds up static change and rains hyper abrasive Lunar dust
| into things I think I've read for one.
| hanniabu wrote:
| Makes more sense now than ever with the advent of starlink.
| _Microft wrote:
| I have seen lots of complaints from astronomers about Starlink
| interfering with optical observations but cannot remember
| hearing about radioastronomy being affected.
|
| On the other hand - if it is up there, it sure can reflect
| radiosignals from Earth back again.
|
| Has anyone heard about Starlink and the radioastronomy
| community?
| gammarator wrote:
| The impact of these constellations on radio astronomy is
| arguably worse, not least because it's harder for the average
| person to see the impact.
|
| https://www.thespacereview.com/article/3702/1
|
| (They don't just reflect radio waves, they broadcast them!)
| _Microft wrote:
| Thanks!
| whimsicalism wrote:
| There's just no way that we as a society when deciding
| between "some shiny new satellite thing produced by an
| American corporation" versus "the quality of the VLAs
| operations" will pick the latter.
|
| It pains me to say it, but the average person does not know
| what the VLA is, nor care at all.
| hutzlibu wrote:
| I am not an average person, but have not heard of the VLA
| before either ..
|
| Anyway, evem when you rephrase it:
|
| Do you want fast internet everywhere?
|
| Or better conditions for science to maybe find aliens?
|
| Not many people would vote for science. Which is
| economically understandable, so I am all for a moon
| observatory.
| whimsicalism wrote:
| It's not just science to find aliens, radio astronomy
| answers so many questions that we might not even think to
| ask - and it is not cost feasible to do all of those
| observations from space. It's as if in the 18th century,
| you were like "do we want to spend more money on roads?
| or do we want to keep funding these stupid experiments
| that Edison is doing for science?"
| coryrc wrote:
| No. I love space science, but knowing the origin of the
| universe will not bring us indoor lighting,
| refrigeration, clean energy, or anything like that. It is
| valuable in so far as it's worth some investment, but not
| so much it prevents us from providing global Internet.
| DennisP wrote:
| Yes, and in a positive way. Starlink plays a big part in
| funding Starship/Superheavy, and giving it an initial customer
| to get launch volume up. That's what will allow the much lower
| space transportation costs, cited by an astronomer in the
| article as making this observatory feasible.
| jessriedel wrote:
| This is the millionth article on lunar far-side telescopes I've
| seen that conveniently fails to explain why you'd want to place a
| radio telescope on the surface rather than just at the Earth-Moon
| L2 Lagrange point (i.e., the point on the far side of the Moon
| that orbits with the Moon around the Earth and keeps the Moon
| between itself and the Earth). I'm sick of not having this
| obvious question answered, so I dug into it.
|
| Like the lunar surface, a telescope at L2 keeps the Moon
| permanently between itself and the Earth to block incoming radio
| waves. For a fixed telescope size, going down into the Moon's
| gravity well increases costs _tremendously_. And, although doing
| construction in a vacuum is never easy, it 's a lot easier when
| you're in zero-g and you don't need a crane! Unlike the far-side
| surface, L2 has exposure to sunlight for power for ~90% of the
| time. (You would still need a relay satellite in a different
| lunar orbit for communications, of course, just like the far-side
| surface.)
|
| As far as I can tell from browsing the article
|
| https://arxiv.org/abs/2009.12689
|
| and the much more helpful analysis of the lunar radio environment
| that they cite
|
| https://sci-hub.st/https://arc.aiaa.org/doi/pdf/10.2514/6.IA...
|
| the only benefits to going to to the surface is (1) you get
| better shielding of the extremely low frequencies ([?] 1 kHz)
| which are long enough wavelength to diffract around the Earth,
| but don't think those are detectable unless you have a telescope
| that's many kilometers in size. (2) you avoid radio signals from
| satellites in geostationary orbits, but these should be very
| small since the transmitters are pointing toward the Earth.
|
| Indeed, the faculty member who is advising the undergraduate
| intern lead author says
|
| > "The first SETI observations that are done from the lunar
| farside will be done from orbit, there's no question about that,"
| says Andrew Siemion, the director of the Berkeley SETI Research
| Center and the second author on the paper. "I think eventually we
| absolutely want to do something on the surface because we want to
| build a very large aperture telescope, but even when we're at
| that point I don't think that would negate the utility of doing
| things from orbit as well."
|
| and I think he's _downplaying_ how tremendously costly going to
| the surface would be for very little benefit.
|
| EDIT: Note that the FARSIDE array on the surface they mention is
| much better justified, but it's not SETI, it's an _array_ , the
| surface benefits from solar storm shielding, and it probably only
| makes sense because it piggybacks on high bandwidth connection
| for the NASA Lunar Gateway. More details here:
|
| https://www.lpi.usra.edu/leag/white-papers-astronomy/FARSIDE...
|
| https://twitter.com/di_goldene_pave/status/13123915724079554...
| TeMPOraL wrote:
| > _And, although doing construction in a vacuum is never easy,
| it 's a lot easier when you're in zero-g and you don't need a
| crane!_
|
| That's not exactly true just yet!
|
| All our construction knowhow is based on thousands of years of
| building things on Earth's surface, under a constant 1G force
| pulling everything in a single direction, as well as a landmass
| to brace against. Every technique we have has these conditions
| baked in as assumptions; we exploit them all the time, without
| even thinking about it. Like, e.g. if you put some mortar on a
| brick, and then a brick on top of that, you're relying on
| gravity to supply the pressure that makes the two bricks
| strongly bound.
|
| Meanwhile - AFAIK - we have _zero_ experience in constructing
| anything in 0G, beyond assembling some large prefabs. The
| closest we come to microgravity construction is whatever it is
| that underwater welders do, but that 's still not the same.
|
| With this in mind, it may be that for now, building
| installations on Moon's surface will be easier than
| constructing them in space.
| jessriedel wrote:
| I think your overall point is wrong, but it would be a large
| discusssion. So I'll just concentrate on this: a telescope on
| the moon or at L2 will, in fact, be large pre-fab. Indeed, we
| have zero experience building anything in a vacuum in
| gravity, but we have decades of experience assembling pre-fab
| structures in zero gravity vacuum. That's what will be
| easiest.
| hutzlibu wrote:
| His overall point was that we have only experience
| constructing in g and allmost zero experience constructing
| in zero g.
|
| And that seems very true to me.
| manfredo wrote:
| > Meanwhile - AFAIK - we have zero experience in constructing
| anything in 0G, beyond assembling some large prefabs.
|
| Weren't the ISS and Mir constructed in zero G? Well, in free
| fall but that's still zero gravity in effect.
| TeMPOraL wrote:
| That's just assembling large prefabs, though, which I
| explicitly excluded from my "zero experience" observation.
| manfredo wrote:
| Wouldn't construction of an orbital observatory consist
| of putting together prefabs? Not to mention, modern
| construction often does consist of putting together
| prefabricated pieces so saying we have no experience with
| construction in zero G only putting together
| prefabricated components is somewhat contradictory.
| TeMPOraL wrote:
| That depends if that was what the original comment meant.
|
| But still, I fail to see how attaching prefabs in 0G is
| going to be easier than doing it in 1G, or even 0.166G.
| It's nice to have a well-defined "down" direction and a
| landmass to brace against. You don't need station keeping
| and magic trickery to keep angular momentum in check.
|
| The main difficulty I'd see with assembling prefabs on
| the Moon would be landing them.
| koheripbal wrote:
| The article literally says that a satellite in orbit is likely
| the first step.
|
| Also, the further you are from the moon - the worse the
| shielding.
| jessriedel wrote:
| First, the orbital option described in the article is _not_
| L2 but rather a _low_ lunar orbit which spends only a small
| fraction of it 's time in the lunar shadow.
|
| Second, in my comment I literally quote the "first step"
| claim and explain why it's an extreme understatement, in
| particular because the shielding is _not_ worse except for
| undetectable wavelengths and sources not actually pointed at
| the telescope. It 's like saying we should we should build
| transparent houses so we get more vitamin D but of course as
| a first step we should go outside or take a multivitamin.
| jvanderbot wrote:
| From this study:
| https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...
|
| The sun is cited as a significant source of noise that can be
| shielded by the lunar body.
| jessriedel wrote:
| Yes, thanks! That's mentioned in my edit (although it should
| just be "solar wind" rather than "solar storm") and the
| twitter thread I link. Note that that's only a particular
| (though valuable) frequency range, and that it's still
| unclear to me whether it's cheaper to go down to the lunar
| surface rather than just build a 10 times larger telescope at
| L2.
| ArtWomb wrote:
| There's a NASA funded lunar colony simulation game for MS-DOS
| circa 1991. You begin with $10K ;)
|
| Playable on archive via DOSBox:
|
| https://archive.org/details/msdos_Moonbase_1990
| Rebelgecko wrote:
| There's also 2010's _Moonbase: Alpha_ [1], which became
| notorious due to how it applied text-to-speech on in-game chat
| messages [2][3]
|
| 1: https://store.steampowered.com/app/39000/Moonbase_Alpha/
|
| 2: https://youtu.be/Hv6RbEOlqRo
|
| 3: https://youtu.be/CNPKXfb3rws
| thepete2 wrote:
| It runs in the browser? Archive.org is awesome :)
| aurizon wrote:
| A number of smaller dishes can be made that will robotically
| unfurl. With the ability to drop a number of them on a flat
| maria. They will be made with as large as possible self
| levelling/rotating ability. They can be each driven with their
| own solar array and will have optical data links so they can work
| as a large array. They will need an optically linked set of
| orbiters - which is doable, that can report sequentially. This is
| a fairly complex task, but once the design is settled and works
| well, it can be tested and then it can be replicated and an array
| gradually built with successor dishes. The dishes can be improved
| as flaws emerge. Being mainly made of aluminum, with vaccuum/dust
| proof bearings with solar shades it will need to tolerate the
| temperature range. I think this is a good idea as the other side
| of the moon is indeed a quiet zone. The lunar lagrange point is
| also a good place, however the lagrange point will be a hard
| place for a number of dishes to be sited apart while maintaining
| precision array positioning.
| Mr_lavos wrote:
| Yes please.
| raverbashing wrote:
| I think we need at least some 50yrs of physics to understand how
| to even begin tapping into the cosmic internet
|
| As with fusion and processing power, some things are faster if
| you wait for the advancements instead of building it with today's
| technology.
| jvanderbot wrote:
| Y'all might be interested in a robotically assembled km-scale
| antenna on the farside.
|
| https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...
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(page generated 2020-10-03 23:00 UTC)