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There are a number of Near Earth Asteroids that are dynamically easy to reach (i.e., with very low delta-V's). The "Plymouth Rock" presentation to the NASA Small Bodies Assessment Group (SBAG) last year lists 12 that could be reached with Orion. These are being found fairly rapidly, so there is no shortage of targets.

Back in 2001/2002 or somewhere thereabouts, I got to attend a NASA Institute for Advanced Concepts (NIAC) meeting. This was the same meeting where I saw the most amazing presentation I've ever seen, Brad Edwards presenting his work on the Space Elevator. (It's also where I ended up with up Buzz Aldrin's name badge as a souvenir, but that's another story).

One of the other presenters though was these guys from Sikorsky:

http://www.niac.usra.edu/studies/516Keith.html

Presenting their study "on the potential for the use of autonomous vertical takeoff and landing (VTOL) vehicles for affordable package delivery.", which is to say A fleet of autonomous vehicles which would fly to your house and land in the driveway and drop off your latest purchases from Amazon.com, or pick up packages for delivery elsewhere.

Honestly the whole idea was clearly madness, but they were very serious and had put a lot of thought into it. Their final report (at the link above) is worthwhile browsing for anyone interested in the issues involved.

I don't think they had considered things like kids using the system to take joy-rides for example.

G.

I can't see that happening in the foreseeable future. As you note, the reliability of such a system is unmodelable and it's a critical parameter since your costs will blow up if you have to fetch the damn things all of the time. It looks like they're having to use optimistic parameters for the stuff they can model to get the thing to break even.

I don't know the relative costs of labor, fuel, et al. for package delivery, but I'm having trouble believing such a system can provide a significant economic advantage without breakthroughs which are over the horizon. Assuming a city is organized into blocks they should get strictly less than a 1/sqrt(2) improvement in distance traveled to service a network of delivery sites. So fuel cost per pound of cargo has to be reasonably close to ground transport in order to maintain fuel cost parity. The savings would have to be in labor and maintenance cost. I'm not sure this has much of an advantage in labor either, due to the reliability issues above, and also because I would expect loading UAVs to require more labor than loading trucks.

Back in 2001/2002 or somewhere thereabouts, I got to attend a NASA Institute for Advanced Concepts (NIAC) meeting. This was the same meeting where I saw the most amazing presentation I've ever seen, Brad Edwards presenting his work on the Space Elevator. (It's also where I ended up with up Buzz Aldrin's name badge as a souvenir, but that's another story).

One of the other presenters though was these guys from Sikorsky:

http://www.niac.usra.edu/studies/516Keith.html

Presenting their study "on the potential for the use of autonomous vertical takeoff and landing (VTOL) vehicles for affordable package delivery.", which is to say A fleet of autonomous vehicles which would fly to your house and land in the driveway and drop off your latest purchases from Amazon.com, or pick up packages for delivery elsewhere.

Honestly the whole idea was clearly madness, but they were very serious and had put a lot of thought into it. Their final report (at the link above) is worthwhile browsing for anyone interested in the issues involved.

I don't think they had considered things like kids using the system to take joy-rides for example.

G.

The new budget revives the NASA Institute for Advanced Concepts (NIAC), which is the part of NASA which previously studied space elevators. The NIAC was one of the parts of NASA which was cancelled to fund Constellation. Also, there have been a few Centennial Challenges related to space elevators, like the tether challenge and the beam power challenge.

http://www.niac.usra.edu/files/studies/final_report/428Boston.pdf

One of the best studies done on extraterrestrial cave habitation. Reports like this are one of the reasons why it was such a travesty that Griffin shut down NIAC, just to raid their budget for Constellation.

not much of a magnetic field

Well, that is an interesting point. It has a liquid core. It has a fair amount of magnetization of its surface.

So, it had a magnetic field, presumably from a core dynamo like the Earth's. To me, the question is, did the core dynamo die some long time ago, or is Mars currently undergoing a magnetic field reversal, as the Earth does regularly (i.e., was had a billion years ago, or a few thousand) ? The vast consensus is that the Mars magnetic field died a long time ago, but I think it is more provocative to hypothesis an ongoing field reversal, and see what observables could come from that.

From your link, silicosis occurs due to particles less than 10 micrometers wide. Regolith is typically more than 30 micrometers wide.

And yet:

While lunar dust is not the same type of crystalline silica known to cause such disease, about 20 percent of the lunar regolith by weight is smaller than 20m- much of which is respirable. In addition, lunar dust has a very high surface to volume ratio and contains fully reduced (metallic) iron, present as nanometer-sized deposits within the lunar dust agglutinates, a form of iron not found in terrestrial soils.

Furthermore:

Preliminary results suggest that lunar dust simulants do, in fact, generate reactive oxygen species and so could trigger pulmonary inflammation comparable to that of SiO2.

Citation.

If you read the original science paper ( http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1601.pdf ) they looked at topology and geology. The ring is not just a surface feature, it's in the deeper geography.

It had been identified in 2006 by visual circularity only by another researcher ( http://impacts.rajmon.cz/data/Impact_database_2009_2.xls or http://impacts.rajmon.cz/data/Impact_database_2009_2.kmz ). The Italian researchers did some of the geology to support that.

More geology is needed, you want to find impact breccia and shatter cones and so forth. But there's more there than "Dude, it's round!".

Well, I thought that they were a system of cracks spreading out from the largest crater on Phobos, Stickney (not visible on the still image in the story, but visible edge-on in the lower right in the movie, or here. It was thought that the impact that created Stickney nearly tore Phobos apart, leaving prominent scars all over the surface, but apparently the system of grooves is far more complex, as was actually determined by the Mars Express mission. One of the sources for the wikipedia page on Stickney is for this paper which maps the striations, and suggests they were formed by ejected material from a series of impacts on Mars.

The orbit of Phobos, particularly, has an oddity that has attracted a lot of interest, and more data is always welcomed.

The orbit of Phobos is decaying, presumably due to tidal friction - the work required for Phobos to raise a small tidal bugle in the part of Mars below it. There is nothing surprising in that, per se (Moons inside a geostationary orbit will decay inwards due to tidal friction, Moons outside a geostationary orbit will "decay" outwards), but what is surprising is the "Q" required to match the observations. (The Q is total energy in the bulge divided by the rate of energy lost per orbit.) The Q inferred from observations of Phobos's orbital decay, and the rigidity of the Martian surface found from observations of the Martian Solar tide, is about 90. The corresponding Q for the Earth is about 12, but that is mostly due to ocean tides, and the Q inferred for the Earth's mantle is about 280.

So, the Mars-Phobos system has a higher solid-body dissipation than the Earth-Moon system, which is surprising. In nailing this down, all sorts of data have been acquired for Phobos (including eclipse data from the Mars Rovers), but there is always room for more. What the current data should do is provide a tie for the relative longitudes of Phobos and Deimos which (especially if this can be repeated) will help make sure that there are no drifts between the orbits of the two Moons.

By the way, with the current orbital decay, the expected lifetime of the orbits is somewhere in the 20 to 40 million year range - it seems unlikely that we just happen to catch Phobos at its end-of-life, which has raised speculation about its decay being time variable.

Moving the ISS to a Lagrange Point would require an enormous amount of fuel, and getting that fuel to orbit. You would need to attach engines, and the station structure cannot handle the force.

If you read the commenters original comment, he mentioned "an" ISS, not "the" ISS. There's absolutely no reason that you couldn't just launch some Bigelow space station modules to a Lagrange point and set up a new space station there.

There is also currently no way of getting supplies and people there.

I suspect that's largely what the point of "Flexible Path" largely is -- to create an infrastructure for ferrying supplies and people between points in space. You can get things/people to a Lagrange point (or a NEO, or Phobos) if you have a dedicated "true" spacecraft which doesn't also have to lug around the mass necessary for launching people into orbit and performing reentry.

For a good idea of what the "Flexible Path" might involve, I suggest reading through this 2004 study led by Wes Huntress for the International Academy of Astronautics, "The Next Steps in Exploring Deep Space." It describes how an incremental architecture can be used to progressive expand exploration outwards from LEO, to Lagrange points, to NEOs, to the Lunar surface, to the Martian moons, and finally to Mars itself.

http://www.lpi.usra.edu/lunar/strategies/AdvisoryGroupReports/iaa_report.pdf

It's also in the Middle of Nowhere. So getting to it is going to be very expensive.

I once saw a presentation at a conference on telescopes, in that case about a similarly quiet location Dome C, also in Antarctica. They had pretty advanced ideas, including cost estimates. The shipping costs of a container by boat and then by some sort of big snowmobile weren't that ridiculously expensive. I forgot the numbers, but it was probably several orders of magnitude cheaper than sending anything to space and probably even cheaper than loading a big telescope in the back of your Boeing 747. Expect some big telescopes in Antarctica in ten years or so.

Here is the complete timeline of the Luna missions: Luna Missions.

Maybe. But if you look at pictures taken towards all four directions from the landing site it doesn't appear to have landed all that close to the edge of the crater.

Who cares about some junky old probe?

A bunch of people, at least in the Lunar and planetary science community. Here is a review paper, and another on the physics return from LLR. We know where the Moon is at the sub-cm level without Lunakhod 1, but recovering this array would help determine Lunar rotation. Even though the Moon is commonly regarded as a dead body, it isn't, and these data might help to resolve this. There is a free libration of the Moon of unknown origin, so it would be good to have data from yet another point on the surface.

Forgot to proof read my link: http://www.lpi.usra.edu/education/explore/capsules/

What I said isn't an approval of the use of this method, just a recognition that the acceleration experienced to land at the end could be successful in not killing the astronauts.

Luckily for you, these are already in place:

http://en.wikipedia.org/wiki/Lunar_Laser_Ranging_Experiment
http://www.lpi.usra.edu/lunar/missions/apollo/apollo_11/experiments/lrr/

Most of the research concerning space-based radiation shielding was done under the umbrella of the now defunct Nasa Institute for Advanced Concepts. ...

Actually, when I wrote a review article back in 1991-- quite a while before NIAC even was conceived-- it was already by no means anything like a new concept.

HA! I should known better to put "contemporary government funded" before "research"! %P I'm a major Space aficionado myself -- part of my brain must have segfaulted. :P ( strictly speaking NASA is not a government agency, but the money needed for the research they do in large part does come from the government, and therefore by proxy it's "government funded" ;) )

jdb2

By the way I'm honored ( and shocked/surprised! ) that someone of your caliber actually read and replied to one of my messages. I'm one of your fans by the way! ( Now I feel like an idiot )

Most of the research concerning space-based radiation shielding was done under the umbrella of the now defunct Nasa Institute for Advanced Concepts. ...

Actually, when I wrote a review article back in 1991-- quite a while before NIAC even was conceived-- it was already by no means anything like a new concept.

Most of the research concerning space-based radiation shielding was done under the umbrella of the now defunct Nasa Institute for Advanced Concepts. One proposal, based on "multipole electrostatics" was developed to protect against not only space-borne radiation, but micrometeorites. See the /. story or here

Here's another one that uses some of the plasma ejected from a spacecraft's propulsion system ( eg. VASIMIR ) to set up a huge and extremely powerful magnetic field around the manned section of the spacecraft in order to create a "plasma magnetic shield".

Also, let's not forget that, as one poster mentioned, M2P2 ( Mini-Magnetospheric Plasma Propulsion -- see here ) can be used as a propulsion mechanism whereby it deflects the solar wind and also as a shield against space born radiation. In a nutshell, it operates on the principle of a positive feedback loop wherein initially a magnetic field created by a conventional magnet traps injected ionized helium which itself strengthens the magnetic field which traps even more ionized helium and so on.

It's really sad NASA shut down one of their most promising research institutes. But, all the studies are still there, archived for some interesting reading. I highly recommend it. :)

jdb2

Most of the research concerning space-based radiation shielding was done under the umbrella of the now defunct Nasa Institute for Advanced Concepts. One proposal, based on "multipole electrostatics" was developed to protect against not only space-borne radiation, but micrometeorites. See the /. story or here

Here's another one that uses some of the plasma ejected from a spacecraft's propulsion system ( eg. VASIMIR ) to set up a huge and extremely powerful magnetic field around the manned section of the spacecraft in order to create a "plasma magnetic shield".

Also, let's not forget that, as one poster mentioned, M2P2 ( Mini-Magnetospheric Plasma Propulsion -- see here ) can be used as a propulsion mechanism whereby it deflects the solar wind and also as a shield against space born radiation. In a nutshell, it operates on the principle of a positive feedback loop wherein initially a magnetic field created by a conventional magnet traps injected ionized helium which itself strengthens the magnetic field which traps even more ionized helium and so on.

It's really sad NASA shut down one of their most promising research institutes. But, all the studies are still there, archived for some interesting reading. I highly recommend it. :)

jdb2

Most of the research concerning space-based radiation shielding was done under the umbrella of the now defunct Nasa Institute for Advanced Concepts. One proposal, based on "multipole electrostatics" was developed to protect against not only space-borne radiation, but micrometeorites. See the /. story or here

Here's another one that uses some of the plasma ejected from a spacecraft's propulsion system ( eg. VASIMIR ) to set up a huge and extremely powerful magnetic field around the manned section of the spacecraft in order to create a "plasma magnetic shield".

Also, let's not forget that, as one poster mentioned, M2P2 ( Mini-Magnetospheric Plasma Propulsion -- see here ) can be used as a propulsion mechanism whereby it deflects the solar wind and also as a shield against space born radiation. In a nutshell, it operates on the principle of a positive feedback loop wherein initially a magnetic field created by a conventional magnet traps injected ionized helium which itself strengthens the magnetic field which traps even more ionized helium and so on.

It's really sad NASA shut down one of their most promising research institutes. But, all the studies are still there, archived for some interesting reading. I highly recommend it. :)

jdb2

Most of the research concerning space-based radiation shielding was done under the umbrella of the now defunct Nasa Institute for Advanced Concepts. One proposal, based on "multipole electrostatics" was developed to protect against not only space-borne radiation, but micrometeorites. See the /. story or here

Here's another one that uses some of the plasma ejected from a spacecraft's propulsion system ( eg. VASIMIR ) to set up a huge and extremely powerful magnetic field around the manned section of the spacecraft in order to create a "plasma magnetic shield".

Also, let's not forget that, as one poster mentioned, M2P2 ( Mini-Magnetospheric Plasma Propulsion -- see here ) can be used as a propulsion mechanism whereby it deflects the solar wind and also as a shield against space born radiation. In a nutshell, it operates on the principle of a positive feedback loop wherein initially a magnetic field created by a conventional magnet traps injected ionized helium which itself strengthens the magnetic field which traps even more ionized helium and so on.

It's really sad NASA shut down one of their most promising research institutes. But, all the studies are still there, archived for some interesting reading. I highly recommend it. :)

jdb2

They have one, that's where I pulled that from. I just forgot to add the link.
Here it is.

They operate in different wavelength bands - Hubble is not an long-wave IR telescope. The space analogy for SOFIA is the 85 centimeter Spitzer telescope.

These telescopes operate in the IR so their wavelengths are longer and thus their resolutions are poorer for a given size telescope.

Here are the numbers :

So the score card is: Hubble 0.1 Arc Sec (best); Keck 0.3 Arc Sec many other telescopes are doing as well as the Keck; SOFIA greater than 2.0 arc sec

Note that radio Very Long Baseline Interferometry (VLBI) can routinely do factions of a milliarcsecond resolution, or a factor of 100 times better than Hubble. This requires synthesizing a telescope the size of the Earth, which you can do in the radio.

The telescope will be exposed to the elements during flight: this photo of the telescope installation shows that the aircraft will be flying around with a 3x3 m hole in its fuselage.

The buffetting and general vibration levels must be huge.
here is how they plan to compensate.

The telescope will be exposed to the elements during flight: this photo of the telescope installation shows that the aircraft will be flying around with a 3x3 m hole in its fuselage.

The buffetting and general vibration levels must be huge.
here is how they plan to compensate.

It's been discussed at several recent conferences (AGU, LPSC) and was the main focus of Spirit's scientific research all through the last (Martian) summer.

Rain or snow, like virga, on Mars may not be consisting of water only. Here is the Wikipedia entry on virga:
http://en.wikipedia.org/wiki/Virga

Also Universities Space Research Association has some information on virga:
http://epod.usra.edu/archive/epodviewer.php3?oid=47776
They have a excellent NOAA photo of virga.

There ain't much going on there.

Apologies, the Apollo mission did do some great stuff for science but most of it could be done by robot these days. That is progress.

People can't go to Mars, because it would be a one-way trip.

Read this in the NY Times.

It's just too expensive

With $55 billion you could feed, clothe an educate every man women and child in Rwanda for a decade, assuming their GDP is about $3bn.

and there's nothing to do up there that we couldn't do with robots.

Sample return would be much easier and cheaper without bulky, fragile humans.

Much better to spend the billions and billions of dollars on lots of probes, better very-long-range telescopes

Are we alone in the universe? Manned missions won't tell us, bigger telescopes might.

"Sufficiently power," of course, depends on your mission goals as well. An RTG will give you consistent power for a long time, whereas the solar cells will have issues managing eclipses and long-term degradation from radiation exposure. A Voyager-like flyby would be better suited for an all-solar approach rather than a Galileo-type orbit (and eclipse) all the time in strong radiation belts. History has also shown that it is far from trivial to deploy large solar arrays, even when you have humans present, and the size of these arrays are huge.

A very nice summary of solar cell technology and future plans can be found over at the USRA site.

The abundance of Titanium and Uranium on the moon makes it a clear choice. We need to build a nuclear-direct refinery/smelter of titanium. The strategic metal in turn will make some pretty cool spacecraft right on the moon away from the burdensome gravity of earth.

I'll go!!

Let's say that a shuttle could carry up a mile of ribbon. That's 44,000 shuttle launches (22K + counterweight tether.) !!! So, tell me... what will this Space Elevator do that can't be done in the 44,000 shuttle launches NOT COUNTING the dilithium we'll spend getting the counterweight into place?

For this reason, the feasibility studies so far (e.g., the Edwards report) target deployment strategies where first a very low-capacity "pioneer" elevator is established using O(5) conventional rocket launches, then this initial ribbon is reinforced with additional ribbons carried up by climbers on the elevator itself. Over the course of many months and many reinforcements, a high-capacity elevator is built that can bring large-scale payloads to orbit. Obviously an ability to bond these ribbons together at high speed would have to be found -- another thing for the list of Really Hard Engineering Problems needing solution here.

Within this strategy the full counterweight is built up is exactly the same way: Incrementally with mass lifted from the ground, once the pioneer elevator (with its small counterweight) is completed.

The NASA source doesn't specify at what radius the thickness is measured, leading me to believe that the "1000 light years" figure references an average, or representative, thickness. According to the summary (although curiously unmentioned in TFA) this new discovery seems to pertain specifically to the Milky Way's thickness at the Galactic core, where it is substantially thicker than at points located further down the arms (as illustrated in this side view).

You're raising an important point, but there aren't any practical technologies that can replace rockets today. SpaceShipOne's approach doesn't work to get into orbit.

The main problem with chemical rockets isn't the efficiency of the rocket, but the fact that most of the fuel you carry is required to carry the rest of your fuel up to the altitude where it is to be burnt. There is a hard physical limit to how efficient (and hence cheap) the method of launch by chemical rockets can become.

There are other, more efficient approaches in development. The most promising are nuclear-powered rockets (using a nuclear reactor to heat hydrogen propellant) and laser-illuminated heat-exchanging rockets, where a ground-based huge multi-megawatt array of lasers illuminate a heat-exchanger on the spacecraft, which in turn heats the liquid hydrogen propellant. Both methods save weight, propellant and energy by not carrying oxidizer in the launch vehicle, the vast majority of the fuel for chemical rockets is in fact oxidizing material like liquid oxygen. And both these approaches could lower the cost to orbit by more than an order of magnitude, but sadly progress in spacecraft propulsion moves at a glacial pace. There are huge up-front development costs to almost every approach. What is needed is a bigger governmental budget and some visionary leadership. Real visionary, not pretend-visionary.

For an explanation of the latter approach, see http://www.niac.usra.edu/files/studies/final_report/897Kare.pdf. I wouldn't bet my money on nuclear rockets being allowed anytime soon, they are after all _nucular_. For a general description of these hypothetical technologies, see http://en.wikipedia.org/wiki/Spacecraft_propulsion.

As for exotic approaches like space elevators, fountains and the like, these methods are either too close to fundamental engineering limits, too expensive and fragile, or both. It is my opinion that the R&D money should be spent on more promising ideas. The laser-illuminated thingie in particular looks very promising.

Hope at least the parent poster reads my comment, I always read Slashdot comments a day after the story is posted because I hate to dodge the unmoderated trolls.

Mars lacks...water? Really? Given the body of research which indicates it has permafrost, I think you may want to check your facts.

Doctor Bradley C. Edwards did a study for NIAC who funded his research (when it was still around). This is a summary of his work.

Can't find a link to the original study atm, which has more detail.

Actually, that's pretty inaccurate. The moon's low gravity and lack of atmosphere are actually major advantages for an industrial base (producing, for instance, giant orbital solar power stations to provide the world with clean energy). The lack of atmosphere also makes it quite a good place to build ultra-sensitive optical & radio telescopes (although advances in computational methods are making that less of an advantage every year). In my opinion, Mars is a much more difficult place to set up a base -- at least the moon's proximity makes it easy to get people back if things go wrong.

As far as radiation goes, one metre of lunar regolith reduces radiation doses due to cosmic rays and even unusually large solar flares to harmless levels. A Radiation Safety Analysis for Lunar Lava Tubes -- this considers lava tubes in particular, but the results are more widely applicable. Several studies have been carried out which suggest that many suitable lava tubes exist on the moon which with a minimum of preparation could be used as shelters for lightweight (possibly inflatable) habitat structures. Robotic technology would be required to (a) survey tubes for suitability and (b) prepare such a site for human arrival.

Finally, while Reading University is a fine institution and has one of the best cybernetics departments in the country, I'm not convinced that they're trying to solve the right problem. I feel that best results would be achieved by developing automated techniques for quickly and accurately surveying large numbers of potential sites, and then developing equipment that can be pre-deployed and then used by humans to prepare a site quickly and easily (i.e. within a few hours) on arrival.

Figures, noone bothered googling the sources in question, check this out : http://www.niac.usra.edu/studies/1047Bae.html

Those are some awesome links.

I'm reading a PDF about Modular Laser Launch and I'm realizing nobody will ever fund this. However! If you had a tracking system that could follow a pinpoint location on a launch vehicle, and a 100MW laser that could continuously fire, then you could take down an incoming ICBM. It seems like this is the way to get this project started. Tell the DOD that the same device that can launch things into space can also destroy them.

This is normally a taboo area for me as the tirades from the 'see no evil' brigade are normally more then I can stomach and aren't worth the time, however I have to say that from what I've read there's fairly significant circumstantial evidence that would imply they're already here and have been for quite some time. I don't necessarily believe that we're in contact with aliens but at the same time I can't prove otherwise. A theory has to be disproved or discredited before it can be discarded. Some of the people in the following links make some pretty big statements and the 'official' response is normally petty personal and defamatory attack which leads me to be just a little suspicious. Why deride someone when you can prove him wrong with fact? From what I've seen over the last decade regarding the BS media and outright lies from officials and governments I think if I had to I'd side with the ufoligists when it comes to trustworthiness. These are some of the best links I've found... anywayz as they say, The Truth is Out There. http://profile.myspace.com/index.cfm?fuseaction=us er.viewprofile&friendid=62955347 http://www.disclosureproject.org/ http://ida.wr.usgs.gov/html/m15012/m1501228.html http://www.lpi.usra.edu/resources/apollo/frame/?AS 15-P-9625

A few years ago there were reports of far more advanced methods of dealing with cam pirates.

They apparently can encode info such as theatre location into audio watermarks, photograph relevant areas/people where characteristic reflections from lenses focused towards the screen are detected, and degrade recordings through light pulses that are not (very?) noticeable to viewers.

Camera image sensors generally are sensitive to IR, but have it blocked by filtering (which likely would increase reflections in that spectrum). Some have modified webcams for IR use by removing internal filtering. Ironically exposed film apparently works as a filter to pass IR while blocking the visible spectrum pretty well. The link includes a graph indicating that the sensors in cameras, before filtering is added, are actually more sensitive to IR than the visible spectrum.

Taking a camcorder into a theatre is a bad idea. It's too bad we've got people being searched, and apparently photographed too. Seems like there's no privacy anywhere. It reminds me of that PC virus that turned on peoples webcams without them knowing it. Kinda makes one laugh and then groan.

Much of this depends greatly on the relative size of the lava tube and the thickness of the crust covering the tube.

We're very used to observing lava tubes here on Earth, whereas lava tubes on Mars (very thin atmosphere, much lower gravity, different rock/lava composition) may behave quite differently.

I like the lava tube theory. The Tharsis volcanoes are much larger than earth volcanoes, the idea that these holes are tiny pinpricks into massive lava tubes is certainly intriguing. That they appear on an ancient lava plain lends much credence to the theory. The big question, when assuming these are gargantuan lava tubes, is where the exit is. To form a tube, we can assume one thing: At the exit location must exist a unique condition, such as over a precipice, where the lava was not obstructed by itself - otherwise it would pile up, slow itself down, and have filled or partially filled the tube as the obstructed lava cooled and hardened.

Perhaps on Mars, due to the lack of atmosphere and cold conditions, the surface of lava flows harden quickly even though molten rock continues to flow underneath? The mystery of where the lava went would still be intriguing if this were true. Perhaps the behavior of lava on Mars is so different that a non-constricting endpoint is not required but rather that simply a downhill flow could generate this result due to differences in viscosity, coherence, and adherence as well as the well known atmospheric and gravitational differences.

In the paper http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1371 .pdf, further reading turns up that illumination from one of the seven cave floors was captured. Current estimate for depth of the Dena cave is approximately 130m. Since the sides of these holes didn't reflect either, its safe to assume the diameter of each of the caves is considerably larger than the skylights that we're seeing. Those are some pretty large holes!

If you read the preprint (PDF), you'd note that luckily, one of the caves actually was imaged with the floor sunlit, giving the authors the ability to calculate the depth of that particular cave. This was covered on May 23rd on the Planetary Society blog.

FYI, here's the original science presentation that the news reports are based on. It's an abstract from the recent Lunar and Planetary Science Conference. This means that the work hasn't yet been peer reviewed but it's still interesting. http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1371 .pdf

OK, I feel bad about my mattress joke being modded "informative". So here's informative for you. They've apparently researched lots of cool things, from the design of space elevators, to space hotels for astronauts visiting mars. It seems like much of their work is looking at the feasibility of bringing things that seem like science fiction into reality. All their papers are available as .pdf files. I wish I had the time to read them all, but I do plan on reading a few.

http://www.niac.usra.edu/studies/studies.jsp

Seems to me like it's worth 1/4000th of NASA's budget.

An extended abstract from the Lunar Planetary Science Conference :

http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1371 .pdf

An extended abstract from the Lunar Planetary Science Conference :

http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1371 .pdf

• "Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures", Bevan M. French (Smithsonian Institution), http://www.lpi.usra.edu/publications/books/CB-954/ CB-954.intro.html
• "Stalking the Wily Shatter Cone: A Critical Guide for Impact Crater Hunters", Bevan M. French (Smithsonian Institution), Impact Field Studies Group newsletter, Winter 2005, online at http://web.eps.utk.edu/ifsg_files/newsletter/Winte r_2005.pdf
• "Shatter cones: Branched, rapid fractures formed by shock impact", Amir Sagy, Jay Fineberg, Zeev Reches, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109 2004, online at http://www.agu.org/pubs/crossref/2004/2004JB003016 .shtml (for a fee), http://www.whoi.edu/science/GG/geodynamics/2005/im ages2005/sagy04_JGR.pdf, http://earthquakes.ou.edu/reches/Publications/Sagy _JGR.pdf, and others