So, are those frost-heave cracks that form the polygonal terrain really flat, or do they present a certain amount of vertical relief?

I feel like we're trying to blind-land this thing in a garden amongst hedgerows -- it's lovely if you land in the garden, but landing on a hedgerow could ruin your whole day...

-the other Doug

Count me in on that idea, Nick! 'Have Space Suit, Will Travel' would make a great mini-series! And the nice thing about the format is that if one book needed three or four hour segments, it would get it, while others might only need one or two.

I've long felt that a similar format for Niven's 'Tales of Known Space' could work very, very well on TV. Some short stories would work well in a single hour format, and you could spend six or eight segments on, say, 'Ringworld' or 'Crashlander'...

-the other Doug

As far as absolutely honest-to-its-roots science fiction on TV, I think the list is shortened to a very few, the outstanding example being the PBS production, in 1980, of Ursula leGuin's 'Lathe of Heaven.' A masterful filming of a very complex and moody book.

-the other Doug

Oh, yes -- 'West Wing' is, IMHO, one of the best-written shows that has ever graced American television. And as much as I enjoyed it for its story telling, I found it one of the brightest comedies I had ever seen.

I'm completely a combination of Doug and Stu. I enjoy most s.f. TV and film productions (though some truly lame things, like Saturn 3 and Will Smith's I, Robot are just too bad for me to maintain interest). I enjoy Dr. Who and Torchwood, I watch Star Trek and Star Wars with great enjoyment. (I will point out that the writing and production values on both Dr. Who and Torchwood have risen to far greater heights than the kiddie show values you saw on Dr. Who throughout its first couple of decades.)

And yet, given the choice, my TV will be set on Mythbusters, Master Blasters, Top Gear, or some archeology or palentology documentary on one of the docu-networks.

The set of relatively permanently stored programming on my digital video recorder gives you a pretty good idea -- about 12 science/space documentaries (including 'Roving Mars' and 'Mars Rocks: One Year Later'), about 4 other various documentaries, a few sitcoms (Murphy Brown among others), and about 7 unwatched episodes of Star Trek: DS9 and Star Trek: Voyager.

-the other Doug

History is replete with examples of small groups of people (and sometimes just solitary individuals) who fail to comprehend the consequences of their decisions -- until you hit the OSM (which, for want of a swear jar, I'll simply translate as the "Ooops Moment").

For example, Chernobyl literally exploded because a test engineer decided to see what would happen if they let the core coolng water draw down without replenishment... *sigh*...

-the other Doug

Besides, it's not like there's a long cruise phase during which problems might crop up, right? Last I saw, the Moon isn't more than a few days away (unless you take a *real* slow route).

-the other Doug

Really? Interesting -- you didn't get that impression from the detailed documentary that ran on NASA-TV six times a day for two months... they referred more to "X-ray detectors," IIRC.

Good to know -- thanks, Del!

-the other Doug

JV strikes me as somewhat overengineered for a disposable one-flight vehicle, and somewhat underengineered for a prototype of a recoverable manned spacecraft.

It's a good foundation for the development of a manned vehicle -- but there are quite a few changes you'd want to make before adding a crew, I think.

-the other Doug

Designs can be quite dissimilar. Chandra, for example, has "mirrors" that resemble concentric tubes which funnel X-rays to the detector. Nothing like a focusing mirror set or a CCD array in that baby.

-the other Doug

Dan? I think you need to sit down, take a stress pill, and think things through...



-the other Doug

Ah, but what form does this take? Are we looking forward to hearing Colossus intone "This is the voice of World Control"? Or Stewie Griffin crying "Victory is mine!"?

Or are we simply at the point where I say "What are we going to do tonight, Brain?"



-the other Doug

The U.S. alone has more than twenty thousand thermonuclear devices, at varying states of age and maintenance, lying around in storehouses around the world. Most of them contain a fair supply of weapons-grade plutonium. We're probably talking *tons* of weapons-grade plutonium in existence today.

How many weapons would you have to cannibalize to construct enough RTGs for, say, a dozen outer-planet missions? One? Ten? Twenty?

Is it at least *possible* that we need those outer planet missions more than we need those very few weapons (out of a large stockpile)?

It just seems to me that saying there's a shortage of plutonium is not correct. We just have to be willing to lose a few bombs out of an enormous stockpile in order to replenish the supply available for RTGs.

-the other Doug

My understanding has always been that gravity assists work by robbing a body of a bit of its rotational velocity by flying along with its rotating gravity field. The Sun rotates -- why ought this process not work with the Sun?

-the other Doug

Free fall is the key way of describing it. A satellite in orbit is always falling towards the Earth, at the standard rate at which any object falls toward the Earth from that height. It's just going fast enough in a vector, as Nick pointed out, transverse to "down" that the Earth's curved surface falls away from the satellite as fast as the satellite falls toward it.

You can experience free-fall without being in orbit -- most well-known is the KC-135 "vomit comet" trainers that NASA flies, which basically have the airplanes fall freely along a diving arc for about 40 seconds at a time. But you can observe the same effect in an elevator that falls down a shaft without touching the walls. Both you and the elevator would be falling at the same rate, so you would experience "weightlessness" while both of you fell. (You'd experience very short-term but extremely high G-forces when you got to the bottom of the shaft, though...)

-the other Doug

I think I saw an IguanaCon namebadge in there somewhere...

-the other Doug

As Jim said, some mods would have to be removed, and an orbiter would have to be *significantly* modified in order for HST to fit in its payload bay (for a variety of reasons, Columbia was the only orbiter whose bay was suitable for returning HST, and plans said that it was going to be used for that task prior to its destruction).

But while landing with a significant payload in the bay can make things a little dicey under some circumstances, it's just plain impossible that a Shuttle would be allowed to lift off with a payload it can't land with. Otherwise, most all of the ascent abort modes would be worthless -- you can't take time in an RTLS abort, for example, to open the payload bay doors and dump the contents...

-the other Doug

My thoughts exactly. In fact, I'm pretty sure what you label Triumph, Emprise and Pathfinder are the craters I was labeling A, B and C. In other words, the destinations I had pointed out a year or so ago.

Taking a trip up to the fresh crater would be a bonus in this traverse concept.

I will note that you can jog to the east of the old track we took south and avoid most of the soft ripple country. Assuming the wheel holds out, you could get up to the general area we're discussing in only a few months.

-the other Doug

Well -- if there was flour on it, not dust, and it was close to the flour's natural angle of repose, and if I kept my coffee table at a 30 degree angle, I could answer the question... *smile*...

I'm mostly thinking that, even with a relatively slow, soft impact, even a small vibration might shift rock/salt dust if it's near the dust's natural angle of repose. Of course, we've likely gotten more of a jolt from descending down this slope than we could generate with the IDD.

I will point out that you don't see a lot of dust collected on 30-degree slopes of exposed rocks in the area, and the only things around to clean them off are winds and seismic shocks. One might hope that a combination of this tilt and whatever natural vibrations plus winds might tend to clean Spirit off as time goes on, here.

Still, I think we need to generate some way to shake these things so the dust can shake off...

-the other Doug

Well... we're at a 30-degree angle. How difficult would it be to use the IDD to "tap" the rover deck a few times? Maybe get the larger clumps to fall off?

No brushing, just a few taps...

-the other Doug

I was trying to come up with words that would form the acronym KOOL-AID, but first I had to change the name of gamma rays to kappa rays... *sigh*...

-the other Doug

Yes! Your 3:38 and 3:51 images are *exactly* what I saw with my naked eye. A coppery feel to the whole scene, edging to an ochre-ish gold along the southeast limb.

-the other Doug

Well -- in re rendezvous issues, my thoughts come back to the fact that the U.S. has yet to prove a capability of autonomous rendezvous. A DoD test was attempted a few years ago, and it ran out of fuel before it achieved station-keeping with its target.

I grant you that the Russians have been doing it for years, and the Europeans will be jumping into the fray within the next month. But that's in LEO, where ground tracking data can be instantaneously incorporated into a vehicle's on-board solutions.

I'm also thinking of how rendezvous works. Your sample-carrying pods will have to be the passive targets -- your weight penalties are highest for the vehicles that you actually land on Mars, so the extra prop you need for rendezvous maneuvers will all have to ride in your orbiter. Making multiple rendezvous means you have to adjust the orbiter's orbit for every object you want to meet up with. Unless the sample pods are all in nearly identical orbits, and most importantly are in nearly the same place in those orbits at a given time, you could require from weeks to months of operations trying to reach each one. And if you end up with any significant out-of-plane elements, you exceed the available energy required to rendezvous pretty quickly.

So, for example, if you end up with two sample containers in nearly identical orbits but, say, separated by 120 degrees of orbit arc, you'll need to phase your orbiter back or forward through a third of an orbit, which is pretty energy-intensive.

And remember, you have to loft all of the fuel you need to reach your sample pods all the way from the surface of the Earth into Mars orbit. For every ounce of fuel you deliver to LMO, you have to spend thousands of pounds of propellants just to get it there.

Until and unless we demonstrate an autonomous rendezvous/docking capability in LEO that allows a satellite to travel around to various objects in various orbits, I'm not certain we're talking about sometihng that's within our technical competence at the moment...

-the other Doug

I think y'all might be amazed at how quickly, once we do start examining extrasolar planets in situ, such ubiquitous bacteria will fall from the heights of "There is now proof we are not alone in the Universe!" to "That bacteria is nasty -- how do we kill it?"



-the other Doug

Well, here's another thought -- instead of relying solely on Mars Orbit Rendezvous (MOR) to collect up all of your separately-launched samples, why not add to this with an element of Mars Surface Rendezvous (MSR)?

It seems to me that the most challenging part of this architecture, both to land on Mars and to get back up off of it again, is the ascent vehicle.

If you want to sample six types of terrain, would it make sense to land six ascent vehicles and then go hunt their easter eggs in Mars orbit, using up tremendous amounts of propellants in rendezvous maneuvers? Or would it make *more* sense to land only two ascent vehicles, each of which is loaded with samples from three different rovers? (I'm thinking that it *must* be easier and cheaper to design, build and fly two MAVs which can each place 30 kilos of samples into orbit than it is to fly six such vehicles which can each loft 5 kilos of samples.) Yeah, you'd "bunch up" each set of three rover sites into something like 100-km circles around each MAV (assuming your rovers can drive as far as 50 km to deliver their samples), but that seems a small price to pay. Besides, there must be many locations on Mars where you can access several different and interesting geological units within a 100-km circle.

Granted, you'd be betting that your rovers would be able to navigate to your ascent vehicles. But again, success could be a graded event -- if only one of your ascent vehicles worked, or if only one or two rovers were able to deposit samples in each, you'd still be looking at a pretty successful mission.

And you'd only need enough fuel in your Earth return/orbiter vehicle to make two rendezvous maneuvers, not six. That could be a truly substantial mass savings.

Yes, we're talking about spending something similar to what Apollo cost just to get 50 or 60 kilos of Mars back to Earth -- at least four major Ares V-type launches, probably more, and a *lot* of spacecraft all operating at once cost a lot of money. But it's a fraction of what putting men on Mars will cost, and a lot of people would argue it's scientifically justifiable.

-the other Doug

They could always call it the GAmma Ray Burst Observer -- GARBO.

Then again, what do you do when a high-tech orbital observatory announces that it wants to be alone?

-the other Doug