But, Bob -- any feature named "Brigadoon" would only be visible to the outside Universe for one day every 100 years. And in this case, that would mean Saturn years!

-the other Doug

I saw those videos (one from each SRB) on NASA-TV, full size and full resolution, and I completely agree with you, Don. They are amazing.

I was very much taken aback by the sound track -- the cameras had attached microphones. The sound of the motors running was actually not all that noticeable, just a high-pitched, loud hum. But the sound of the air passing them as they fell, becoming thicker and thicker as the boosters descended, causing sounds of metal flexing from deep within the walls of the boosters, was uncanny. It made me feel like I was riding a sinking ship down to the bottom, but violently and hyper-fast.

I guess the best way to describe those films is exhiliarating, and scary!

-the other Doug

Um, no, not Niven... Think of Deja Thoris riding one, you'll figure it out.



-the other Doug (aka John Carter of Mars)

Then go and buy his book... Squyres is very forthcoming in his book about his expectations; he was so tied in to the 90-sol projection that he got a bit, um, shall we say "high strung" whenever anything threatened to steal away even a single sol from the exploration program. He also said he was rather expecting Spirit to be on its very last legs by the time it reached the Columbia Hills.

He talks about getting more and more relaxed about things as time went on and it became apparent that the rovers weren't going to die anytime soon.

-the other Doug

Heck, I'd be happy if they just named a small, run-down-looking Martian crater "The Thoat Barns"...

-the other Doug

Don't forget the Russian Phobos mission. While it did die just before beginning its intensive Phobos encounter, it did get a suite of some pretty high-quality images of Phobos as it approached.

-the other Doug

The impact basins range from 3.55 to 4.2 billion years old, if memory serves, with Imbrium being the youngest of the large basins (even younger, apparently, than Orientale). Not all basins are mare-filled -- especially those on the far side. But of those that do have a mare fill, the basalts we've sampled are on the order of 3.1 to 3.8 billion years old (though there is some support for the concept of areas of western Procellarum being slightly less than a billion years old, and the lavas at the Surveyor 1 site may be less than two billion years old).

In general, though, I wouldn't call the mare basalts "much younger" than the basins themselves -- in most cases, the maria are less than a half-billion years younger than the basins they occupy. Over a 4.5-billion-year lifespan, that makes both of them similarly ancient -- nothing on the Moon can really be fairly called "young," I think. As of about three billion years ago, the Moon had undergone about 98% of all of the major activity it would ever see.

They've dated the basins directly by dating samples of the impact melt created by several basin-forming impacts. I believe they are pretty certain about having dated impact melts from the Imbrium, Serenatatis and Nectaris basins, and have tentatively dated others (such as the 4.2-billion-year-old South Pole-Aitkin Basin) from a few isolated samples returned from Apollo 16, plus analysis of crater counts and degradation of basin structures. IIRC, Imbrium is dated at about 3.55 billion years old, Serenatatis in the 3.8 billion range, and Nectaris being a little older than both, in the 3.9 billion range. (I'm speaking entirely from memory here, but I think I'm close...)

I recall that the lavas in Imbrium were apparently erupted over a period of around 300 million years, beginning hundreds of millions of years after the basin was formed. This effectively killed the theory that lunar lava eruptions were triggered by the basin-forming impacts, though the lava may well have seeped to the surface through cracks formed by basin-forming impacts. It just took hundreds of millions of years for the lavas to start to flow.

While all of the visible maria are no older than about 3.8 billion years, there are pieces of basalt found as clasts in some of the highland breccias that have been dated as old as 4.2 billion years -- so some of the basin-forming impacts must have wiped out very old maria that simply no longer exist.

-the other Doug

For those who maintain an interest in the Apollo moonwalks, Tom Hanks and the people he got to do the moonwalk sequences in his mini-series "From the Earth to the Moon" have put together an IMAX 3-D film called "Magnificent Desolation."

They have re-created highlights from the moonwalks, using the very effective techniques they developed for FTETTM, and filmed them in IMAX 3-D.

From what I've been able to tell, they shot in a "moon room" that provided very bright keylight and a properly dusty surface, with green screen all along the walls. In this film, moreso than in FTETTM, the *real* horizon features will show up in the backgrounds, as appropriate from the various portions of EVAs from different missions that they're using. (There is a very, very short shot in the trailer showing Jim Irwin falling down in front of Falcon, and Hadley Delta spun crazily in the background as the camera moved to get out of Irwin's way.)

Here's a link to the site. I am *really* looking forward to seeing this one -- it comes out in late September here in the U.S.

IMAX film "Magnificent Desolation"

-the other Doug

Tycho was created something like 109 million years ago, according to clues from the Apollo 17 landing site.

But yeah, I was thinking a lot more of the basin-forming impacts, since that's the size of impact that is being discussed by the authors of the article that triggered this thread. Tycho was a large impact, but nowhere near the size of a basin-forming impact. However, I suppose it would be more analagous to the Chixculub event than a basin-forming impact would have been.

And yes, by the time of the Tycho impact, the Moon was close to where it is now, and was therefore taking several weeks to rotate on its axis. My bad.

-the other Doug

The Moon rotated a heck of a lot faster 3.8 billion years ago than it does now. It was also a heck of a lot closer to the Earth. And it may well not have become tidally locked with Earth yet, so it may well have rotated faster than it revolved around its primary.

-the other Doug

Maybe these dark rocks are fragments of what lies beneath the evaporite layer? Erebus is the largest impact structure we've come close to, we ought to be traveling right now over the degraded remains of its ejecta blanket. The soft mostly-salt evaporite rocks that probably made up most of the ejecta blanket have weathered down to a flat plain, but if small, very shocked pieces of whatever underlied the evaporite layer were mixed in with the evaporite in the ejecta blanket, I would expect to see such chunks lying out on the ground, the softer evaporite having eroded away around it.

-the other Doug

Gusev was selected as a landing site because orbital photography *very* strongly suggests it once held a lake.

What we've found are the Columbia Hills, which seem to pre-date the lake phase of Gusev -- the rocks generally aren't water-altered enough to have been on the bottom or shore of the lake, so the hills seem to have been uplifted above the "water line" prior to the formation of the lake.

The other thing we've found are the basaltic lava flows that have covered the entire floor of Gusev. There is plenty of unaltered olivine in those basaltic rocks, showing that the basalt "cap" has never been significantly wet.

Somewhere in Gusev, there *must* be exposed lacustrine materials -- the rocks formed and altered on the lakebed and at its shores.

If there is any way to make a best guess at where we might be able to get to such lacustrine materials, and if they are even remotely within reach, I'd spend Spirit's last days getting there and looking at them.

However, I've got to think that we can't identify such rocks easily from a distance, and the landforms visible in orbital images thus far haven't been helpful in this regard, either. So, either the lacustrine materials are effectively buried and can't be reached by surface exploration, or if they can be, we don't know where to look for them.

(As an aside, I think we probably *have* seen one or two examples of lacustrine materials up on Husband Hill and West Spur, especially hematitic rocks like Pot of Gold, that were lobbed there by impact events. But since they've been loose rocks and not part of bedrock outcrops, you can't get any details on their context within Gusev and its history.)

-the other Doug

All I can say about the need for a fatter data pipe than the MERs have enjoyed is what Steve Squyres said at an Ames Research Center colloquium, when asked what he wanted to do better or differently next time. In increasing order of importance, he said he wanted:

3 -- to fly the Raman spectrometer.

2 -- to have a more intelligent Rover that you could tell, in a quick interface, "Go over to that rock, give me a Mossbauer integration, then an APXS integration, and while you're doing that, tell me the atmospheric tau value and take a quick panorama." Rather than having to spend ten hours a day crafting the specific command strings to make all of that happen.

1 -- to have a much fatter data pipe from the rovers back to Earth.

Even though I know exactly why MTO got axed, I still think something like it is going to be needed at some point down the road... Maybe it's just that I'm getting older, and I want to see the high-definition video stuff from Mars before I die.

-the other Doug

Of course, we could always call it Nosmo, who was King of the Moon Men. I believe they came up with that name from looking at a No Smoking sign and re-arranging the space -- NOSMO KING.

Then again, we could use Chauncey and Edgar as the names for new TNOs... as in:

"There's something you don't see every day, Chauncey."

"What's that, Edgar?"

"A six-foot-tall metal-munching mouse."

-the other Doug

Really? Mars Observer was re-flown as Mars Global Surveyor. Mars Climate Orbiter was re-flown as Mars Odyssey. Mars Polar Lander will be re-flown as the Phoenix mission.

Let's see -- of the Mars probes that have been lost over the past dozen years, that leaves Deep Space Two as the only set of flight instruments on a lost spacecraft that haven't had a mission created to allow re-flight.

-the other Doug

Oh, I knew an "uprated MRO" with a much fatter data pipe back to Earth wouldn't have been able to serve the same pure telecom purposes as MTO, because of the orbit requirements for doing imaging.

I just want the fatter pipe, is all. After all, we're stuck with something in an MRO-type orbit for MSL's relay, regardless -- if that's all we're going to have, I'd rather have that much fatter pipe on it. Otherwise, we might as well scale back the data gathering capabilities of MSL, 'cause we'll *never* get all the data return that the current design can flood back at us with the pipes that will be available to us.

Had NASA a clue that MTO was going to be canceled, say, a year or two ago, I would have pushed for adjusting the MRO design to allow for at least a *somewhat* fatter pipe back to Earth. The timing of the MTO cancelation, however, made that completely impossible.

-the other Doug

It was a gorgeous launch -- the Atlas V is a sight to behold as it rises.

I found one thing almost alarming as I watched the launch -- as the bird rose, I noticed that a pipe remained attached to the vehicle, sticking out right where the payload fairing finishes flaring out at the base of the clamshell shroud. One of the launch replays shows it clearly, and in the very close shot, it really does look like it was designed that way. But it still looks very odd to have a pipe sticking three to four feet horizontally out of the payload fairing. I'd imagine it would induce some pretty severe aerodynamic loads.

And actually, a *very* small part of me was hoping that this launch would fail, so that NASA would have to fly a combined MRO/MTO in the next Mars launch window in 2007. That would have given them time to incorporate all of the high-bandwidth telecom capabilities of MTO into the replacement MRO, and we'd be able to get all that data down from MSL that we're now never gonna see... Don't get me wrong, I'm glad MRO is off and in good shape. But a little natural accident forcing Griffin's hand over the MTO issue would have been, I don't know, serendipitous...

-the other Doug

I think this is the biggest influence -- the crater rim controls a lot of the wind patterns and creates an "unstable zone" over a particular patch of the crater floor.

It's very, very common to find such patches of dust devil-scoured dark land in larger Martian craters -- you see them more often than not. And they're almost always off-center patches that resolve down to dark dust devil streaks.

Since you see this effect in a lot of martian craters, it makes sense that crater rims of a given size range induce atmospheric instabilities that encourage dust devil formation.

Now, dust devils *have* been seen on Mars outside of craters (by MGS), so crater rims affecting the local winds are not the only things that encourage dust devil formation. But the evidence seems to suggest that it can be a major factor.

-the other Doug

Actually, it was planned for Soyuz 1/2 -- after Komarov's launch on Soyuz 1, a three-man crew was set to launch in Soyuz 2 within two days. A rendezvous and docking, followed by transfer of two of the Soyuz 2 crew into Soyuz 1, was planned. (This is documented in several different places, and is also inherent in the Soviet announcement of the launch of Soyuz 1 -- the Sovs never gave a number to the first flight of a new spacecraft. The announcement of the vehicle as Soyuz 1 was a confirmation to the West that a second Soyuz was planned to fly within a few days.)

After one of Soyuz 1's solar panels failed to deploy, the planned launch of Soyuz 2 was canceled and the Soviets began to plan for Komarov's early return (although, apparently, some Soviet mission planners argued for Soyuz 2 to fly, and its EVA crewmen to go out and fix the solar panel problem). It's a *very* good thing they didn't launch Soyuz 2, since it shared the same problem Soyuz 1 had with the "sticky" parachute canister. Had Soyuz 2 flown, it would have crashed and killed its crew, as well.

As for the Soyuz 2/3 mission, I'm pretty certain that it was always designed to be a rendezvous and docking between a manned Soyuz and an unmanned Soyuz. (We're talking about the Soyuz 2/3 flight as it was designed after the Soyuz 1 accident.) I don't think the lone Soyuz crewman was going to transfer to the unmanned vehicle had the docking worked (which it didn't).

-the other Doug

While I found Singapore to be a beautiful city, at the moment I'm glad to be in Minneapolis, Minnesota, USA -- where I just picked up a copy of Roving Mars yesterday, at a Barnes & Noble bookstore.

It's very, very well-written -- you can very clearly hear Squyres' voice in it. And his enthusiasm. He also doesn't hide his darker side, which comes out a bit in that pair of PBS documentaries, as well. For instance, he speaks of JPL colleagues working on an opposing bid for the 2001 lander mission as "the opposition," with whom he shunned contact during the bidding process. "We can be friends later" is how he puts it, talking about avoiding them and even refusing to speak to them as he passed them on the walkways of the JPL campus.

But it is a very, very well-written chronicle of the process of creating and flying robotic Mars explorers. I'm sure we'll all own a copy in the near future...

-the other Doug

Now, there's an interesting new perspective on Areology -- that Mars is one giant Fig Newton!

And who knows -- maybe there are chocolate fudge volcanoes on Venus...

-the other Doug

All I know is, it may be a good thing that the Shuttle fleet is grounded for a bit -- the Interplanetary Mattress Police will be after them!



-the other Doug

I don't know, Richard -- I agree with Bob, I think it's a little bit of a stretch to posit a second terrestrial body as the source of the Heavy Bombardment impactors.

Instead, as has been discussed in the Jupiter board, it's more likely that Jupiter and Saturn moved into a gravitational resonance that disturbed "loose" bodies in the Asteroid Belt. Some of them were probably ejected from the Solar System altogether, but a lot came raining in towards the inner System, pelting the rocky planets with huge impacts. Even so, a lot of the bodies probably simply fell into the Sun, so a *lot* of bodies had to have been tumbled inward.

-the other Doug

I wholeheartedly agree with your sentiment, Emily. But we have to face the fact that we live in the world of the sound bite, the news cycle, and the MTV attention span.

Those of us who enjoy news of planetary exploration generally have longer-than-average attention spans and an ability to retain interest in a subject for longer than a single news cycle. But, more and more, I've come to the conclusion that we're the exceptions. Of course, we have resources like this forum with which to supplement what the organized media offer, and without it I think most of us would be going slowly insane...

As for my own two cents -- I'm glad to have both you and Bruce as contributors to this forum. I know that, even though you both write for special-interest publications, you have to keep your professional work at a certain level. Whereas here, y'all can get as detailed and as esoteric as you want, and anyone who wants any further background to help them understand just asks for clarification. It's refreshing and vastly more satisfying (to me and, I suspect, to a lot of the people here) than any other newsgroup, chat group, forum or single publication could hope to be.



-the other Doug

I'm in for Sol 717.

-the other Doug