Well EPG, you posted to a couple of spots so I'm going to try to consolidate the ideas here.

The Baseline Detection Concept for CAPS advocates:

1) High-res telescopes w/advanced detector arrays
2) Coordinated telescope control for NEO surveying and tracking (I assume that means multiple telescopes)
3) rapid spectral imaging for NEO identification and characterization
4) Interferometric techniques to obtain precision orbit determination when required

to this list I would add
A) Rapid slewing ability to acquire sudden objects of interest (i.e. Gamma Ray Bursts or novas)
B) Full spectrum analysis as quickly as possible.

I would give an EML-1 #s 1, 3, A, and B. Possibly 2 and 3 as well, but I'm having a hard time picturing a Cluster-type interferometric mission in a halo orbit around EML-1. Hard to dock with and service and upgrade. The Moon's got all four and B, but definitely would have a limited FOV for A. When you can slew in three dimensions you're talking considerable value in capability. How you would quantify that qualitative value for a parametric cost/benefit analysis I'm not sure.

I believe that we are going to find out some REALLY interesting stuff about these objects once we're free of the spectral blanket of the Earth's atmosphere. Oh wait, we already doing that, 'cept it's all out of focus for our purposes. Perhaps some enterprising young astronomers can snag some time on some of the orbital scopes to start doing some early local investigations across the spectrum with existing equipment.

Do the objects we're looking for show up better in different wavelengths? Perhaps bleeding off heat in the infrared during their rotation? What does the UV spectrum look like? What does it tell us about the objects' composition?

All, I think, very relevant questions, but of course woefully uninteresting to the astronomical community at large (but we want to see planets around other stars! Future homes for humanity!) and therefore woefully underfunded.

Hey Raoul, do you know offhand how much astronomical data they got in storage down in Strasbourg? I'm pretty sure it's in the petabytes.

Of course the science community cherry picks its data, and there could be a good deal of resource misallocation in the form of intellectual knowledge versus practical (and likely relevant) knowledge all so that papers can be published on esoteric topics. Hmmmm. I wonder which ones we've got up there that would be good for this sort of thing. I'll have to look into that.

Thing is, EPG, I've reviewed the paper which outlines the proposal and seems to serve as the baseline:

"Comet/Asteroid Protection System (CAPS): A Space-Based System Concept for Revolutionizing Earth Protection and Utilization of Near-Earth Objects". IAC-02-IAA.13.4/Q.5.1.01.

Houston? October? Hey, this was at the World Space Congress! Darn, I missed that presentation. I do remember the RASC concept from last year, though, and have seen the pretty graphics (I'll bet those cost a pretty penny in cost allocation accounting). Thing is, Lunar siting seems to be the assumed site, though not expressly presented as such in the paper except through the graphics.

The negatives brought up in the paper against an orbital interferometer aren't that strong.

-The authors argue that moving the interferometer and maintaining a stable baseline poses its own set of problems.

I would argue that the Cluster mission is giving us practice in that regard (and probably is providing relevant but overlooked data with regards to what both an orbital and Lunar base would experience swinging through the magnetotail). Our work in orbital mechanics is pretty advanced at this point, with SOHO and Genesis, and soon the NGST in halo orbits around libration points, and GEO comm sats in co-location configurations. Maybe Cluster could do a practice mission in a halo orbit around EML-1.

But does it have to be an interferometer right from the get-go? Maybe not, though a single craft or station can absolutely do it while offering a lot of other possibilities for added value as well.

-The authors argue that propulsion system would be required which consumes propellant and introduces disturbances into the system that may take a long time to damp out.

My reply to that is that the Hubble Space Telescope has served us faithfully and well for quite a while now, and look what that goes through. The EML-1 actually helps to minimize dV requirements, and therefore fuel, and the second issue, that of vibrations, is an engineering solution and I know we've got some pretty good technology in that regard. Besides, the consumables of a Lunar base will be no laughing matter either.

I also note that in the November 2003 issue of Discover magazine Ed Weiler is recognized for his work with the Hubble. He notes that Hubble manages to do science nearly 50% of the time, making it one of the most efficient telescopes ever. As of 12/31/02, Hubble data has given rise to 3,577 papers in refereed journals.

Bruce Margon, Assoc. Dir. of Space Telescope Science Institute states that 8% of all papers published in the top 5 astronomy journals in 2002 were based on Hubble data, more than twice as many as any ground-based scope.

It's easy for roboticists (roboticysts?) to bandy around the cost of the Hubble because it's relatively easy to identify in public budgets, at least to a rough approximation. You can never truly capture the cost of something because of creative accounting and hidden budgeting.

It's far harder to quantify the value that's been returned by the human-tended and upgraded scope. Everyone recognizes the power of the many images that it's returned. Seeing the look in a little kids' eyes on the Strasbourg tram as they examine the Hubble prints I've just given them out of my lecture notes is priceless. The value is clearly there, but how do you quantify that against the cost and risk that everyone's throwing at you.

Even with its attendant cost, nothing has done more for the popularization of astronomy for the general public, worldwide, than the Hubble Telescope, a human-tended machine of wonderful magnificance BECAUSE it is human-tended.

Plus, the summary and conclusion doesn't specifically advocate a Lunar base, nor is siting considered in the report. Obviously, siting on the Moon is better for interferometric stuff, but location, location, location is of critical importance. Put it on the equator and you'll see the whole sky, but that's the hardest kind of base to support because of the two-week effect. Put it at the pole and you've got near-continuous power, stable temps, and cryogenic craters, but which half of the sky do you want to see, or do you have to support two bases?

It uses such broad phrases as "Detection telescopes would be orbiting and/or lunar surface based". The graphics and educational materials obviously assume a Lunar base, and I have no doubt that Mr. Mazanek personally advocates such, but nevertheless...

I invite you to revisit the report, but from the point of view of a small craft in a halo orbit around EML-1. It offers cheap station keeping, even working to help by pushing objects that fall behind forward towards the "point", and those that get ahead are pulled back. A simple halo orbit at a right angle to the E-M line helps to, I guess, provide a sort of inertial balance around the "point" against the gravity wells of the Moon and the Earth. It works for SOHO, that's all you gotta know! The EML-1 is a Freaky confluence of forces, man.

You don't have to worry about getting too far into the Moon's SOI (and not really at all given the weird interplay of forces), so you don't have to brake into the Moon's well, saving on dV in the earliest stages. But it's also serviceable, and can act as a servicing point for ESL-1 and ESL-2 probes as well, timing their returns on low-energy trajectories, with little relative velocity on arrival, to coincide with servicing missions to the EML-1. A Hubble, but further out, and where you can do several at the same time. Hard to do that at a Moon base.

And for all of the Mars folks out there, I invite you to revisit the EML-1 point in the context of the Report of the National Commission on Space: "Pioneering the Space Frontier", to wit:

"The lowest energy transfer point for travel to or from Mars is the L1 Point...This would be an especially favorable location for a spaceport serving the Mars Run. The L1 Spaceport would facilitate a future intensive buildup of a Mars base.. It would be a spaceborne combined motel/gas station/warehouse/restaurant/garage".

For true cometary survey I'd want something out around Jupiter (maybe JSL-2 or JSL-3?), and by the same token I'd want something out at Mars, at MSL-2, to scan the asteroid belt. These could also come back to EML-1 on low-energy trajectory orbits for servicing and upgrade with the others in the network.

I recognize your concern regarding comets. I read the article in Harper's about the threat of comets, and it was sufficiently lurid that I'm sure more than a few folks soiled their underclothes in terror. They're going to be coming in fast and the swing around the Sun is going to perturb its orbital parameters.

Well tough, we can't afford a Moon base right now, and we can't afford a jaunt to Mars.

We can afford to have an orbital maneuvering vehicle,
we can afford to go out beyond LEO and the cocoon of the Van Allen belts for a trip to EML-1,
we can afford a small spectral telescope array to put at EML-1 (designed to be serviced and upgraded),and
it can all be done from the ISS, and
if our resources are deployed reasonably well, it can be done in the 2010-2015 time frame.

That time frame is far closer than we realize, and a lack of focus and direction in our space efforts is squandering our resources and wasting what we've learned.

Does that mean we won't go to the Moon? Of course not! We need scopes on the Moon, across the whole spectrum, but you're going to have to get the deep space astronomers on board or they're going to fight you every step of the way for the scarce resources deployed to astronomy. On the Moon you will HAVE to concede to the bulk of their wishes, but they will love you once they're there. Consumables will be an issue for a while though, but you get the benefit of being able to conduct crater counting and dating to establish periodicity, or even if it exists, in the impact history much better than our guesses here on Earth.

An EML-1 instrument can be more obviously dedicated, at least at first, to pure asteroid detection. With the help of some of the big orbital scopes, at least part time, we could cast our gaze farther out to the edge of our Solar System and just beyond, providing at least some coverage for comets.

Does that mean we won't go to Mars? Of course not! Mars has a thing or two to teach us about cratering history, planetary formation (though trumped in direct relevance by the Moon and the Aitken Basin), and more. Does what Mars has to offer make it more compelling a priority than the Moon? Eh, probably not.

<<For Earth power generation from space, too little is known about effects of power beamikng on ozone, and effects on climate - >>

Well, an EML-1 would serve as an ideal spot for small-scale initial tests. We're going out there anyway for the asteroid and Sun watching equipment, take out a couple more solar panels and a microwave beamer. See how well we can target and what the localised effects are flying planes through the beams or whatever.

I also think we'll find that once we're out there we'll develop solar cells that capture a broader portion of the spectrum using different doping agents. Not something we can really dedicate a lot of resources to here on Earth; how do you test them? The Moon is the obvious resource base for mass produced solar arrays so we don't have to tear up our own planet to build the final installation. Shipping the materials for solar power satellites from Mars just seems kind of silly.

Speaking of which, relying on computer models to predict microwave effects on the ozone is just as silly as relying on them to predict asteroids/comets, or foam effects on the shuttle, or the possibility of life in the universe, or the value at risk (VAR) in a portfolio (whoops, sorry, financial stuff there). We've got to go out and do it. That's the only way to truly learn.

Besides, once the initial tests are finished and construction begins in GEO, EML-1's existing infrastructure and equipment can be dedicated to supplying power to bases on the Lunar surface, something that Heppenheimer touched on in "Colonies in Space". An EML-1 station is the closest thing we're going to get to a GSO-type satellite in the Moon's orbit, might as well tap into that capability to the greatest extent possible.

<<For EML points, defense use is never openly discussed. EML provides time for evasion of attacks on sensors and communication and control sats; EML also provides a stable location for nuclear power generation, which is good to power both sensors or defensive lasers. Let's hope that the diplomats are effective, and we don't have to spend the money to build one of these things, but in defense, hope is seldom enough...>>

Well, for security I was refering more towards terrorists taking out power generation capabilities. Both North America and Europe have had the surety of their power systems tested recently. Pretty much the worst scenario I can envisage is a suitcase nuke at a nuke plant. It's much harder for terrorists (or thugs so we can include the nascent space capabilities of Iraq that got wiped out a decade ago) to manifest capability in space.

It's not like a terrorist is very likely to get on a crew that's heading out to EML-1 or GEO (the ideal location for the final infrastructure), especially with a bomb. A spy/saboteur for a foreign government with a pinhead bomb, maybe, but a terrorist? Naah.

I'm praying for the peaceful, intergovernmental development of space (at least after we get to the Peaks of Eternal Light at the Lunar South Pole first). I'd like to see OPEC nations and those that have prospered invest some of their petrodollars in the infrastructure that will eventually replace most internal combustion applications, hopefully before the oil runs out or become ridiculously expensive to retrieve. It gives them a reason to work with us, while giving them a stake in the power source of the future. No more second-hand solar power!

I'd also like to see a cathedral on the Moon, built by all of the cultures that use the Moon in their calendars, relying on the definition of the young crescent Moon to determine when holidays start (Ramadan, anyone?), that sort of thing. Build it on the terminator at a mutually agreed upon location (you've got some wiggle in the exact spot because of lunar libration), and have it project a Sun dagger on a particular spot to mark the beginning of each new lunar month, likely tracing out some path over a Saros cycle.

None of the above are going to come quickly, but some can come more quickly than others. I think the quickest results with the greatest opportunity for future growth lies at EML-1. I'm not against the Moon, and actually anxious to get back there, and certainly look forward to Mars and the Asteroids. But let's put things in perspective, what can we really accomplish, given our current resources and capabilities, over the next decade or two?

Cheers,
Ken