Yeah -- unlike some of the other dark spots in the orbital imagery, this (and other black-sand deposits like it) truly appear as dark from the surface as they do from orbit.

I would *have* to think that there is some major compositional difference between the dark sands and the surrounding rocks and soils, to account for the dramatically darker appearance. The fact that the dark sand patches seem to be in the wind shadows of the hills *seems* to explain them as dust fall-out from prevailing winds -- but that then begs the question as to why there should be a major compositional difference between the particles that fall out in such conditions and the particles that have been wind-deposited into the surrounding soils.

-the other Doug

No, they don't, Bruce -- it just seems longer.



-the other Doug

I can think of a mission design that would allow in-situ analysis of Martian rocks and soils.

Land one (or more) big, heavy laboratories. Sell them to Congress as unmanned engineering tests of landing systems for later manned spacecraft. Equip these heavy landers with the types of equipment needed for isotopic analysis and dating analysis, and develop automated sample handling/preparation systems.

Then land a fleet of smaller rovers, all of which have some basic analysis abilities but which are primarily sample-collectors. Land them within roving range of the big, heavy lab.

Then start a multiple-rover trek "home," towards the lab, investigating all of the rocks and soils along the way. As each rover arrives at the lab, it delivers its samples, which are then analyzed and results transmitted back to the PIs here on Earth.

If your rovers are still in good shape, send them out again along different paths, or check out pre-identified sampling targets that your initial survey missed.

If you can land your lab and rovers precisely, you can get a great radial sampling pattern around your lab, out to 50 to 100 km from a central location. The lab is also big and heavy enough that it could deply a seismometer and a heat-flow probe at the base location.

Land six to eight of these lab/rover missions across the Martian globe, and you'll have a pretty good idea what's been happening up there, I think...

-the other Doug

Forgive me for stating the obvious, but this discussion just highlights the need for both a seismic network and a network of heat-flow measurements across the globe of Mars. And Venus. And Mercury, for that matter.

Seems like a somewhat esoteric dataset, I know. But considering the vast implications of an imperfect understanding of the heat-release dynamics of our own planet, I'm beginning to think that *these* are the highest-priority measurements awaiting us...

-the other Doug

Yeah, go ahead... rub it in...



-the other Doug

Actually, Nico, I'd prefer either the North or South Massif...

-the other Doug

Exactly! I hear so much talk about how the ISS is totally useless, scientifically -- and yet, I hear the same people say that there's no reason for people to go back to the Moon because it only interests "a few geologists."

You can't have it both ways! If you want manned spaceflight to do science, don't denigrate real scientific missions because they don't interest anyone except scientists!

Particle accelerators don't excite the public imagination, either, and it's a sure thing that the Katrina victims could use Fermilab's budget right now -- anyone think we ought to shut down Fermilab and go with computer modeling for all future subatomic research?

I didn't think so.

-the other Doug

Chill, Doug, chill... s'okay. For the foreseeable future, I'll be working 60 hours a week, without a management crew that can cover any vacation time, and *still* not making enough money to afford much more than a visit to Duluth.

I was just being a wise-ass, OK? I didn't seriously mean to imply that you're being unfair. I *do* understand.

-the other Doug

Alas, Doug, your point about the US being too costly, in terms of time and budget, for you Europeans is the same issue I have with a European meeting. And your comments about how a European meeting is so much more reasonable are *only* reasonable for, er... you Europeans.

So, I think it's incumbent upon us Americans to come up with a *really* cool site on this side of the pond for our *own* meeting, so that all of you Europeans can sit back and slobber with envy, and complain about how unfair it is that we can go and y'all can't afford it...



-the other Doug

This question has been bothering me for some time:

A lot of data suggests that Mars lost its magnetic field a *long* time ago -- like, in Noachian times. Something like three and a half billion years ago. More than anything else, the pattern of atmospheric depletion suggests this strongly.

There is also significant evidence that Mars has undergone volcanism for almost its entire history -- some lava flows have been dated via crater counts at only 10 million years or so.

The "accepted view" is that Mars lost its magnetic field because its core solidifed. Now, how does it logically make sense that Mars' core cooled so much that it congealed 3.5 billion years ago, but that enough heat was retained in the mantle to drive remarkably extensive volcanic activity for almost the entire remainder (to date) of the history of the planet?

Now, perhaps I am simply uninformed about the process of planetary cooling; it would make sense to me that a planet would cool from the outside in, not from the inside out. If that "common-sense" perception of planetary cooling is wrong, please, someone explain it to me...

In absence of better data about planetary cooling, though, it occurs to me that perhaps what needs to be questioned is not how Mars could be so volcanically active with a cold, congealed core. The appropriate question is whether or not a planet can spin rapidly (one turn in only a few tens of hours), have a molten core, and *not* generate a magnetic field.

After all, we only *theorize* that Earth's magnetic field is generated solely by the rapid rotation of its molten nickel-iron core. We have precious little data about the core/mantle boundary -- it seems possible to me that it is the rotation of the Earth's core/mantle *boundary* layer, and not the rotation of the core itself, which generates the magnetic field.

That would open up the possibility that Mars could *still* have a small molten core which is still driving mantle convection of some form or another. If a change in state, composition or other nature of Mars' core/mantle boundary is what killed its magnetic field, *not* the solidification of its core, that would mean the same thing could possibly happen some day on Earth.

And an Earth without a magnetic field is, in the long run, pretty much an uninhabitable planet.

I'll also toss into this discussion a morsel I read in the past year. Based on motion measurements using the Apollo laser retro-reflectors, one peer-reviewd paper insists that the Moon's observed motions can only be explained if its core is in fact still molten. Not only molten, but rotating at a slightly different rate, and around a slightly offset axis, from the rest of the Moon. (There does seem to be a thick layer of undifferentiated chondritic material overlying the core and a pretty thin layer of mantle; all of the volcanism we see on the lunar surface, it would seem, was the result of both immediate and stored accretion heating.)

And, of course, we all know the Moon has no intrinsic, global magnetic field.

So, once again, the question is begged: how sure are we that a fast-spinning, rocky planet which lacks a global magnetic field *must* have a cold, congealed core?

-the other Doug

Absolutely. After all, fossil fuels are nothing more than storage units for solar energy.

-the other Doug

One of the problems in using the argument "people don't want it" is that we are, by and large, talking about people who are massively uninformed on the subject.

For example, when polled, a majority of people state that they believe the NASA budget is larger than the HHS (Health and Human Services) budget, when NASA's budget is something like 1/100th of HHS's.

Also, the line I hear repeatedly from people who criticize NASA funding is that "we should be spending that money right here, on Earth!"

Ummm... the *entire* NASA budget is spent paying workers, running facilities and procuring materiel -- almost all of that within the U.S. That money IS spent here on Earth.

If people were simply informed of the actual facts, I'd have an urge to trust their judgment. But as it stands, I do not accede to the opinions of an uninformed majority...

-the other Doug

Exactly. And if mini-TES can give us a general idea that these dark sand deposits are all of similar composition and are relatively homogenous, we can characterize an entire unit here with a one- or two-stop visit. I think it's a good time investment.

-the other Doug

Two comments:

Emily -- you're spot-on! One of my favorite lines is "How can it be the 21st century? The cars still have wheels!" The problem with flying cars is that, as far as anyone has been able to manage, a flying car requires a *pilot*, not a driver. It would be tremendously more difficult to train everyone to fly than it is to drive. And look at the accident and fatality rates among drivers -- that would increase almost exponentially if you tried to make billions of drivers into billions of pilots.

In re Martian micro-organisms -- for a virus or bacteria to infect a given host, it has to have mechanisms that directly interact with the host's physiology. Virii, in specific, must be able to alter the host's DNA to replicate the virii. I find it *very* hard to believe that life forms which evolved entirely separately would be able to infect terrestrial organisms. However, alien organisms *could* simply try and live within a terrestrial host and produce toxins (which are not the same thing as infectious agents) which would sicken their hosts. So, while there is a generally miniscule risk that alien micro-organisms could infect terrestrial life, there is a larger risk that they could produce toxins that could endanger terrestrial life.

-the other Doug

Yes, framing the issues is important. That's one reason why NASA *hired* James Cameron (director of such films as Titanic and The Terminator) to help them frame such issues.

Can anyone honestly say that has helped?

This links back to another discussion -- people are motivated by greed and fear, and invariably try and do things the easiest way possible, with the least effort on their parts. If you *really* feel you need a popular upswell of opinion to achieve space flight goals, you need to appeal to the people's fear, greed and/or laziness.

Now, just *how* do you plan to accomplish anything *lasting* if that's how you must frame it, eh?

...*sigh*...

-the other Doug

Ah, the basal geology now becomes apparent. Home Plate isn't an ancient, eroded crater remnant -- it's a salsa bowl!

-the other Doug

I can understand why they want to check out El Dorado. Allegheny is yet another in a series of outcrops, some of which we've already looked at and some of which we're planning on looking at as we approach and investigate Home Plate. But El Dorado is representative of a *lot* of dark sand fields seen in the wind shadows of these hills. If we characterize this one, we'll probably be able to characterize them all (at least in general terms).

And it's now close at hand. If it takes only one or two IDD runs to get all the answers about these dark sand fields, we'll be able to scoot on along to Home Plate. That'll take less time overall than another detailed characterization of yet another outcrop...

-the other Doug

Interesting that the red-green-blue set would generate such a nice ochre Mars, just as it looks from a spacecraft. I don't know if it's a function of the limited resolution my childhood telescope (a 3-inch reflector) had, or what, but whenever I looked at Mars through it, Mars always appeared more pinkish than ochre.

-the other Doug

As someone who just got my very first invite to join AARP (the American Association of Retired Persons), by dint of my turning 50 a couple of months ago, I must say I resemble that remark!

-the other Doug

Well, there's always David Brin's solution. Use a laser to *refrigerate* the probe, and to provide braking thrust against the Sun's gravity.

The idea is to drain the thermal energy into a system that powers a very powerful, very HOT laser. This would be the *only* way to use a "radiator" to shed heat into the photosphere.

A side benefit would be that such a laser would exert *significant* thrust, and it would be aimed at a target that it couldn't much hurt -- the Sun's surface.

The catch, of course, is that we really don't have the technology to build such a hot laser, or to convert the heat we can't reflect away into power for the laser. Once we develop those technologies (if we ever do), then a solar probe is more feasible...

-the other Doug

A few comments...

Bruce and JRehling, most of the "little now" money will be spent on the CEV and its launch vehicle, which are needed to maintain an American manned space presence of *any* kind after the Shuttle fleet is retired. And I'm thinking that the CEV, even with its development costs, will end up costing less in the long run than a re-certification of the Shuttle fleet. Also, it's my impression that the CEV will be overall cheaper to fly than the Shuttle is, which will provide a long-term cost savings. It's actually a move to *lessen* the percentage of the space budget dedicated to maintaining an American manned presence in space.

One good thing about the way the CEV is being designed is that it's a multi-purpose vehicle. Once you have a CEV fleet in operation, you can develop habitat and propulsion modules at your leisure and use the CEV as a taxi to get to and from the "real" mission modules. So, spending the money to develop a CEV *now* won't end up being wasted money -- we'll be able to use the CEV for LEO and ISS operations, even if the LSAM development is delayed or canceled.

As for a majority of Americans not supporting a return to the Moon -- a majority of Americans didn't support the U.S. entry into WWII, either. Until we were attacked. A majority of Americans *do* believe that the Air Force captured a UFO in 1947 and autopsied a bunch of dead gray aliens.

I *guarantee* you that if America were to give up manned spaceflight, it wouldn't be long before a majority of Americans would *insist* that America not be left behind by expanding Chinese and Japanese manned space programs.

And if you think that by killing Shuttle and ISS flights you'll get three planetary flagship missions a year, think again. Funding for unmanned spaceflight would remain the same, if not be cut back a bit, if America got out of the manned space flight business. Cutting funding to one does not mean all that money would get spent on the other.

The main competitor for unmanned spaceflight's funding is NOT manned spaceflight. It's Iraq war spending, Katrina recovery spending, servicing-a-multi-trillion-dollar-national-debt spending, on and on ad nauseum. Killing American manned space flight will *not* significantly increase unmanned spaceflight funding, period. And, with all due respect, you're a fool if you think it will.

Walking away from manned spaceflight is the first step down the path of abandoning *all* significant space exploration. Mark my words.

Oh, and a comment to ljk -- yes, I remember the film Countdown quite well. It was one of the very first films directed by Robert Altman, who went on to direct such classics as M*A*S*H and Nashville. Altman's signature style is already well developed in Countdown, especially his penchant for having his characters talk over each other, like people do in real life.

Countdown was based on a much more well-told version of the story, the novel "The Pilgrim Project' by Hank Searles. That book is based on an actual LSR (Lunar Surface Rendezvous) proposal made in the early 1960s, while NASA was struggling with the "mode decision," how to send men to the Moon. It's a much more plausible scenario, using a Saturn 1B to orbit an Agena/Mercury combination. Actually, the TLI stage consisted of the S-IVB (for stage 1 TLI propulsion), the Agena (for stage 2 TLI propulsion and MCCs), a modified Polaris solid-fuel rocket (to act as a landing brake during the landing phase), a truss with landing legs and small vernier final-phase landing engines, and attached to the truss, a 3-day-duration Mercury capsule.

The flight plan was nearly identical to a Surveyor's -- the stack was aimed directly at a spot on the near side of the Moon, the braking rocket fired at several hundred km altitude, slowed the craft to only a few hundred kph, and the verniers slowed it to a relatively soft landing. If, for any reason, you wanted to abort, there are several opportunities during translunar coast to fire the Agena and/or Polaris perpendicular to the line of flight and place yourself on a free-return trajectory.

The nice character-building catch in Searles' version was that the Mercury/truss combo was *just* too heavy to land. To bring the weight down, they had to slingshot the heat shield away from the spacecraft. So, once you committed to landing, you *had* to land -- you had no way to return to Earth.

Searles' book is also able to get away with basing its main characters on real-life astronauts without specifically naming them. The "old veteran" astronaut, played in the film by Robert Duvall, is never named in the book, but always referred to as "the Colonel." A Marine colonel, in fact. Mercury pioneer. Born in Ohio. The Colonel's original backup was "the Commander." Another Mercury pioneer. Naval aviator. Craggy grin, known for flashing from smiling to icy in milliseconds.

And while offhand mentions were made, here and there, of Glenn and Shepard as if they were other people (just to keep lawsuits at bay, I'm sure), it was a skillful job of using Glenn and Shepard as characters without requiring their permissions...

-the other Doug

Interesting collision between American English and non-American English, there. In Britain, taking a week or two off from work and going somewhere is called "going on holiday" and the summer is the most popular time to do so -- hence, "holiday season."

In the U.S., the holiday season begins on Thanksgiving Day and lasts through New Year's Day. Ask *any* American when holiday season is, and that's what they'll tell you.

-the other Doug

There are stretches of the Belly Band where the "plateau" at the top of the ridge is crenulated with chains of identically-sized, shoulder-to-shoulder craters. That are exactly the same width as the crest of the ridge.

That *strongly* suggests vents to me.

-the other Doug

Go ahead, say "airbags" -- NASA does. The CEV is designed to use a jettisonable, replaceable ablative heat shield that gets discarded after entry. The base then fills up with airbags, and the whole thing bumps down on land.

They're not exactly the same kind of airbags used on Pathfinder and the MERs, though. It's not a "bounce 'til you stop" landing. These airbags deflate as they strike the ground, both attenuating the landing shock and settling the CEV solidly onto the ground. But yes, NASA calls them airbags.

The CEV will also be able to land on water, the airbag cushion will be watertight. And the airbags will serve as a flotation collar in the case of a water landing. But it's designed for a nominal land landing.

-the other Doug

Looks great -- a chocolate cake with sulfate evaporite frosting!



-the other Doug