Hello everybody, I've developed a bit of a fascination with the moon recently, and so I was delighted to read this about a private group in hawai making progress toward putting an unmanned observatory on the moon. I couldn't find any mention of it in either the lunar exploration or private missions section, so I thought I'd start a thread to see what peoples thoughts are on the idea. Is it a good one, and if so why has it not been done before? What exactly will it be used for?

"We see this as a critical phase of work for ILO, as it will solidify the mission’s goals and priorities,"

Looks like they don't know what they want it for themselves. I've seen this debated elsewhere on the subject of NEO detetction, and simply can not seen the point of putting a telescope on the moon, when you've already put it into space. Radio Astronomy from the far side of the moon makes some sense - that I can appreciate. But anything else? Why put it on the Moon? Would a facility like Hubble, sat on the moon, be a better scope than Hubble in LEO or a Hubble like facility at L1/L2.

Yes - in 'free space' you have to manage your pointing, but you're also in a more thermally stable environment (instead of a two weeks on-two weeks off cycle), and have as much electricity as you could want available 24/7 via solar arrays (instead of requiring something else, rtg's etc). Moonquakes don't happen in free space.

A telescope on the moon will take better pictures than one on the Earth - but it won't take better pictures than one in free space, and for the mass involved in putting it on the lunar surface, surely you could design a very stable bus platform using gyros etc and maybe even a larger scope rather than a decent stage and mount for pointing. I can see why they got a UV scope out with Apollo - it was the quickest and easiest way to get that data without building full spacecraft. However, it was a short project that was wrapped up and brought home within hours - not an unmanned facility to be launched and then landed.

Perhaps I'm missing a major piece of the picture - but scopes on the moon - it just doesn't make sense to me.

Doug

The best place to put a space telescope is in one of the Lagrangian points (L2 prefrably facing away from the Sun).
The reason lies in the fact You won' have trouble with glare of the earth nor any (large) Earth occultations.
A telescope on (the backside) of the Moon would have the advantage of less micro-meteroids hitting it but it would have to cope with the lunar dust upon landing

Fewer micrometeorites, but only by half compared to free space. Does the far side of the moon have any less or more micrometeorite strikes than the near side? I can't imagine why it would.

Doug

Nor me. Just less Earthlight, presumably. though relaying data home could be a problem.

However I note that the proposal is for a polar site, rather than a farside one. Also the observatory is described as astrophysical rather than just astronomical. I doubt if optical astronomy would be it's priority. One possibility is infra-red. I can see a site near a lunar pole being easier to keep cold than a free space location.

From http://www.spaceagepub.com/ilo/ilo.overview.html:

"As currently envisioned by SPC, the ILO will be an approximately two-meter dish, multi-wavelength observatory standing at about three meters in height, with communications and solar power gathering capabilities. Several missions and payloads can be added to the ILO to increase the scope of its overall mission. An arm with a water ice ground truth detection capability or a lunar rover are among these possibilities."

Sounds like a radio astronomy payload combined with a possible water prospecting effort, though the latter seems difficult to reconcile with the fact that it's solar-powered...? The requirements analysis for this is gonna be a real joy...

Longevity perhaps? With no orbit boosting needed it wouldnt be limited to the life time of its fuel supply. I get the feeling they would like this to be semi permanant at least, and if they wanted to service or expand it at a later date that might be easier to do on the moon. Interferometry would probably be easier on the moon than space. The site planned is the south pole, so at the right spot it might be possible to have the radio quiteness of the far side and the communications ability of the nearside, without a dedicated relay orbiter. A south pole location would probably let you find a spot with a fairly constant temperature regime as well. You could point the scope at one spot in the sky for longer from the moon, without having the earth cut off the view. I think that there is also some value in proving that it can be done, so if a compelling reason to site on luna came to light later there is a fairly recent precedent.

Could be; the group's stated goal is to work towards a permanent human lunar presence, so this project might be their planned 'seed'. Be interesting to see if they can pay for it, much less actually do it...

It'll be very interesting, and to be honest I'd like to see it happen. But although for some applications a site on the moon makes sense (like nprev said about the infrared, or farside radio, astronomy), it doesn't sound like they've got a solid application + reason for siteing on the moon. Thats a pity because if they did they might have more luck attracting funds

Thanks for the credit, Marsbug, but it was actually Doug & Nigel that mentioned farside radio astronomy & infrared.

Frankly, if I were them I'd try to attract grants from government space agencies, universities & interested private sector organizations to do something with some very quantifiable science return and a little more sexiness, like a rover/ice prospector. Whether or not it's really there (and how much of it there might be) is a huge question still, and the debate won't be decisively settled until in situ exploration occurs.

I don't see the scientific value of a 2m radio astronomy dish at the South Pole, esp. if it's not shielded from the Earth. Am I missing something?

Astronomers have been wrestling with this for a while. There was a meeting at STScI on this about a year ago (link - for some reason this wasn't one where they archived the webcast) in which a bunch of pundits spent three days saying "there are a couple of niches that are well served by the lunar surface, but mostly we want to see what makes economic sense if someone is bound and determined to develop a delivery infrastructure anyway". Or as Dan Lester puts in, the value proposition involves gravity and rock. Farside long-wavelength radio astronomy is one such niche - the aurorae are ferociously emitting sources of noise. Interferometry may be, depending on how fast our ability to do highly controlled stationkeeping develops. And there is an interesting low-lunar-orbit application using occultations for localization of high-energy X- and gamma-ray sources (rocks are cleaner than an atmosphere that way). Some of the tradeoffs will be clearer when we know more about the dust issue. I thought at first that dust was the cause of the bearing freeze on the Apollo 16 UV camera, but on further examination, that was traced to use of an improperly speced lubricant.

Well, for big pie-in-the-sky kind of thinking, you could haul just enough materials to the moon that you could spincast your own mirrors in-situ. Say, a factory for creating 5m hexagonal pieces for a 100m scope. Or multiple scopes, for that matter.

Sorry Doug and Nigel, thanks for pointing out my typo nprev.

I think probably the key advantage of an observatory close to a Lunar base is the same as for Hubble in LEO, proximity to repair. NASA's planning to build its base at the south pole, in one of the areas of constant sunlight (so power and thermal cycles aren't a concern). This might not be the absolute best for radio (though you can selectively put a mountain between the dish and Earth), the real advantage is bottom of the permanently shadowed craters, which at a constant 40 K. You land build a great big cryogenic IR telescope down there , and then just run power/data lines up to the moonbase...

Probably the best way to mitigate dust around lunar optics is to "bake" the surrounding surface; regolith is high in iron and easy heated by microwaves. So, you literally just sweep the area around the scope with a magnetron, melting and solidifying the surface, and removing nearly all sources of dust (except for electrostatic transport, but that's relatively slow)...

Simon

Got it...interesting! Still, for this particular mission, is radio astronomy worth the price of the ride for a 2m dish with no apparent shielding from terrestrial emissions? I really believe that they should rethink their payload choices.

On the subject of a future South Polar lunar base's radio astronomy utility, I don't see a mountain as enough of a barrier to make the instrument 'Earth-quiet'. You'll still get a host of secondary reflections, multipaths, etc. from the surrounding terrain that has a LOS to Earth. In my opinion, a lunar RA observatory is only worthwhile if it's sited somewhere where the Earth is permanently below the horizon (and allowing for nutation, to say nothing of sky coverage concerns).

Oh, forget a 2m dish, just find a suitable crater and build a mini-Arecibo; if you've got a crew around to bang pegs into the ground, the landed mass could be pretty small (mesh and stiffeners for the reflector, three cable-stayed towers, and a box for the receiver). The base will probably have pressurized rovers with a range of around 900 km, so the radio observatory doesn't have to be at the south pole to be human-supported...

http://www.space.com/businesstechnology/07...a_moonbase.html

Simon

The sorts of things that make reasonible lunar astronomical observatories, other than things that really have an advantage being done from the moon (like a farside ultra-low-wave interferometer) are things like the Apollo 16 ultraviolet camera.

If you're going to the moon, can carry an instrument that needs minimal setup and can do nicely with a power supply cord and a ethernet cable, the "no other spacecraft required" design can be an advantage.

An updated version of the Apollo 16 camera could be an Earth-fixed ultraviolet aurora and plasmasphere observations instrument. Carry it off to it's "quiet spot", point it, plug it in, and nearly forget it.

It's utterly not worth the cost of lunar missions to be able to do things like that, but once you have the lunar missions, small, worthwhile science things can "parasitize" on them like getaway specials used to do on the shuttle.

A little news on the farside radio-astronomy idea.