Stargazing Why Aren't There Telescopes on the Moon?

[mfb]

Never mind other-planet rescue; think of just our backyard moon colony or whatever it might be. "Hey Mabel! Seems those guys in Tranquillitatis construction site got themselves into a mess. When is the next launch window? Thursday? Got a craft ready? Oh well, when then? No, not that one, it can't accommodate all of them. Hey you guys up there, how long can you hold out? Two days? Oh well never mind then..."

You don't need launch windows on moon. Keep a spacecraft ready that has supplies for a few days for the crew. It can go to moon orbit at any time, go from there to a transfer orbit, enter the atmosphere of Earth within three days and land. One day more in moon orbit allows to choose from a large range of landing spots if necessary. The ISS has a similar system with the Soyuz that stay attached to it.
Transporting astronauts to the escape vehicle can be tricky, but that is independent of the object you are considering. The time to get home is significantly shorter from moon.

 

[Jon Richfield]

You don't need launch windows on moon. Keep a spacecraft ready that has supplies for a few days for the crew. It can go to moon orbit at any time, go from there to a transfer orbit, enter the atmosphere of Earth within three days and land. One day more in moon orbit allows to choose from a large range of landing spots if necessary. The ISS has a similar system with the Soyuz that stay attached to it.
Transporting astronauts to the escape vehicle can be tricky, but that is independent of the object you are considering. The time to get home is significantly shorter from moon.

You seem to have a very simplistic view of moon launchings and the sort of preparations you need for rescues that you haven't even bothered to characterise yet. We don't even succeed with mine, earthquake, flood, cave, and submarine rescues on Earth, and you seem to think that lunar rescues are just taxi jaunts? And that three days would suffice for unscheduled rescues, and that that would be fast enough even if we could manage it?
Tell me allll about it once you can instance the points of correspondence with and discrepancy from the ISS. Which discrepancies, I might add, are part of the reason why telescopes in orbit, and even colonies in orbit would make more sense than on the moon.
I hope to goodness that whoever plans our space future takes the whole matter of technicalities and objectives a LOT more seriously than you do.

 

[mfb]

and you seem to think that lunar rescues are just taxi jaunts?

No I don't think so. But you can make the necessary preparations. And you probably want that unless the moon base is so large that a quick rescue won't be feasible (or necessary).
On Earth, you don't have a fueled rocket sitting next to everyone to use in case of emergencies.

and that that would be fast enough even if we could manage it?

That was never part of the discussion.

are part of the reason why telescopes in orbit, and even colonies in orbit would make more sense than on the moon.

I fully agree with you on those points, and I don't see the relevance of them for the discussion how long it would take to reach Earth from moon.

I hope to goodness that whoever plans our space future takes the whole matter of technicalities and objectives a LOT more seriously than you do.

There is no need to get personal.

Can you explain where the launch windows would come from?

 

[davenn]

SpaceX will try it again (with the first stage) tomorrow, and they plan to re-use the second stage in the future, too.

that, unfortunately became a dismal failure, exploded a couple of minutes after launch

Dave

 

[Jon Richfield]

that, unfortunately became a dismal failure, exploded a couple of minutes after launch

Dave

Yes. I was not in any way involved,except for being on the same planet more or less, but it still was so painful that I am thinking about other stuff.

 

[Chronos]

The recent launch failure of the ISS resupply mission merely reaffirms our technological ineptitude. God forbid we should ever be compelled to launch multitudes of nuclear missiles to divert a wandering space rock.

 

[Jon Richfield]

The recent launch failure of the ISS resupply mission merely reaffirms our technological ineptitude. God forbid we should ever be compelled to launch multitudes of nuclear missiles to divert a wandering space rock.

Though I am compelled to admit the persuasiveness of your point in the light of that event, we need to see this as a statement on our current status and our need to advance, not necessarily a condemnation of our future prospects in space.
It is not a fundamental principle of our necessarily continuing incompetence. We can and must continue to advance until we can profitably and reliably launch what we need to, on the schedules that we face and safely and reliably.

 

[Chronos]

Agreed. We are not as space competent as we may believe or should be. That is enough reason to not relinquish our dreams of things like space stations or moon bases. Our very survivable will someday depend on out ability to do such things reliably and economically. My issue is in getting out there, we can figure out the economics later. I suspect medieval european royalty had similar concerns about exploring the new world.

 

[mheslep]

Let me add another point- the moon keeps one face pretty much toward the earth. If we put a telescope on the moon on this side, most of the "visible sky" would be the earth. If we put it on the other side, we would have major problems with communicating with it, getting its images and controlling it.

Old thread, but there must be some other objection to a solution via relay satellite in lunar orbit (~2 hour period), or http://www.labspaces.net/pictures/blog/4cd8b1c15732e1289269697_blog.jpg? Forty posts in and I've not seen the objection yet.

 

[SteamKing]

Old thread, but there must be some other objection to a solution via relay satellite in lunar orbit (~2 hour period), or http://www.labspaces.net/pictures/blog/4cd8b1c15732e1289269697_blog.jpg? Forty posts in and I've not seen the objection yet.

If you had infinite funds to spend on a telescope, sure, put a dozen of them of the Dark Side of the Moon and launch a bunch of relay satellites. But, since you have only limited funds, the question must be asked: what would you see thru a telescope from the DS of the Moon that you wouldn't be able to see thru a telescope in Earth orbit? The telescope in Earth orbit is easier to maintain, since you don't have to send the Maytag repairman to the Moon every time something breaks down.

A billion here, a billion there, and pretty soon, you're talking real money.

 

[mheslep]

As the hundred posts or so in the thread discuss, there are many problems with a lunar scope, but I don't think communication with the dark side is an intractable one.

 

[davenn]

As the hundred posts or so in the thread discuss, there are many problems with a lunar scope, but I don't think communication with the dark side is an intractable one.

as Steamking said, it isn't worth the cost or effort ... it can all be done from Earth orbit for a tiny fraction of the cost

 

[Jon Richfield]

Or even farside moon orbit if there is a serious need for shielding from Earthside radiation.
Moon-based observatories would have a lot of disadvantages in comparison.

 

[mfb]

Earth/Moon L2 is still completely shielded from radiation from Earth. It is also easy to relay signals via a satellite at L4/L5 or in various Moon orbits.

 

[Vanadium 50]

I don't think communication with the dark side is an intractable one.

I don't think any of the problems are intractable. This is a question of practicality, not possibility. You plop a Surveyor on the moon, have it wait until night, take a few shots of the sky, and send 'em back when you're in daylight again. But that surely would not be worth the effort.

 

[mheslep]

Earth/Moon L2 is still completely shielded from radiation from Earth. It is also easy to relay signals via a satellite at L4/L5 or in various Moon orbits.

Right, as I indicated, lunar dark side surface to L2, relay to L4 and relay to earth. I'm guessing this has long been the proposed communication solution for any kind of long term installation on the dark side.
http://www.labspaces.net/pictures/blog/4cd8b1c15732e1289269697_blog.jpg

 

[15characters]

What's the point of a moon telescope - spending 50% of the time in sunlight it would miss a lot

and it would be impossible to track anything for longer than a two week period.

 

[Chronos]

The problem with a lunar telescope is not one of feasibility, it is one of motivation. Does the potential benefit justify the effort? At this point that may be dubious, but, we never learn the benefits of exploration without accepting some level of risk. I like the idea of putting aside political squabbles in exchange for acquiring knowledge that may benefit all of humanity. We did it before by putting a man on the moon. We can do it again by continuing that mission in a cooperative sense. I believe most earthlings would overwhelmingly favor that option over enhancing our ability to destroy life on earth

 

[15characters]

The problem with a lunar telescope is not one of feasibility, it is one of motivation. Does the potential benefit justify the effort? At this point that may be dubious, but, we never learn the benefits of exploration without accepting some level of risk. I like the idea of putting aside political squabbles in exchange for acquiring knowledge that may benefit all of humanity. We did it before by putting a man on the moon. We can do it again by continuing that mission in a cooperative sense. I believe most earthlings would overwhelmingly favor that option over enhancing our ability to destroy life on earth

Ok so if I gave you the choice of a telescope in orbit on a remote controlled satellite.

Or the same telescope, but planted on the dusty surface of the moon...you would prefer the moon telescope? - because it's more prestigious right?

That's ridiculous.

For example what if I gave you choice between a telescope in orbit at a distance of 400,000km, and the same telescope on the moon. Why is the moon one better?

 

[Chronos]

The dusty surface of the moon which has no wind to waft the dust around? It's not about prestige, its about mastering the technological challenges needed to pull off the job. Your argument makes about as much sense as - why risk sailing across the sea when you can just carve a message on a coconut and toss it into the outgoing tide?

 

[15characters]

Well if it's about mastering the technological "challenges" and not about gathering useful data, then why bother building a telescope at all, why not build an F1 car on the moon?

I mean just to kind of like show we can do it. It will be hard and expensive. Lives may be lost. But at the end we'll say look "we built an F1 car on the moon. How cool is that?"

And people will say "yeah, but what's the point". And we say, "oh just to show that we can master technological challenges at any expense for no apparent reason."

"Oh, and by the way we spent like 200 billion US$ on the project so there's no funding left for anything else now."

"Here have a look at some photos of an F1 car "on the moon. It looks just like an F1 car on Earth except it's way more expensive and impractical way of getting exactly the same data"

And then someone says, well can we get some pictures of the car with the Orion constellation in the background?

"No, that's not possible..."

 

[15characters]

The dusty surface of the moon which has no wind to waft the dust around? It's not about prestige, its about mastering the technological challenges needed to pull off the job. Your argument makes about as much sense as - why risk sailing across the sea when you can just carve a message on a coconut and toss it into the outgoing tide?

If you're goal is to deliver a written message across the ocean why sail there in a raft if you could just send an email?

 

[Chronos]

A paper just appeared on Arxiv; http://arxiv.org/abs/1510.01435,18-Months Operation of Lunar-based Ultraviolet Telescope: A Highly Stable Photometric Performance, summarizing the first 18 months of operation of a lunar robotic telescope called the Chang'e 3, deployed by the Chinese National Space Agency in late 2013. Evidently the Chinese space program flies pretty low on western media, given this is the first I've heard of it. So the question 'why no telescope on the moon?' is more accurately framed as 'why no NASA or EU sponsored telescopes on the moon?'. The advantages of a lunar based telescope are discussed here; http://phys.scichina.com:8083/sciGe/fileup/PDF/11yg0558.pdf, echoing many of the sentiments noted in this thread. Obviously, China found sufficient merit [and funding] for such a project.

 

[15characters]

A paper just appeared...The advantages of a lunar based telescope are discussed here; http://phys.scichina.com:8083/sciGe/fileup/PDF/11yg0558.pdf, echoing many of the sentiments noted in this thread. Obviously, China found sufficient merit [and funding] for such a project.

A satellite in a circular orbit 400,000km from Earth is:

• just as "stable" as the moon
• equally free of any atmosphere / ionosphere
• better at being aimed at a single star for years
• also capable of detecting UV

So...what are the advantages of a lunar scope as compared to a satellite scope?

And, also, if the lunar scope already exists what's the point of this thread? and why no interest in the data?

 

[mheslep]

So...what are the advantages of a lunar scope as compared to a satellite scope?

As mentioned in the paper:

3) The temperature in the permanent shadow regions (PSRs) at both poles of the Moon could be as low as 30 K [3]. PSRs are therefore rare ideal conditions for infrared observations.

With respect to stability, what's the typical pointing stability of a space based instrument as compared one on a body? The paper references 10 day observations.

 

[mfb]

just as "stable" as the moon

Not sure about that. For Gaia, a huge amount of work is necessary to determine its orientation in space (while rotating slowly) with the required precision. On the moon this is easier, unless moon quakes are significant.