I think the point was that the backshells and 'chutes from VL1, VL2 and MPF have never been seen in MOC imagery. Even though the backshell was tentatively identified in MPF surface images, nothing that looks like it (or its 'chute) has been seen in MOC images of the area, even though they're fairly certain they've identified the lander's location.

-the other Doug

Yes, I think that some form of imaging might someday be possible. And it would be a very worthwhile experiment. I think sounding is a lot more likely to yield data than radar -- something like an active seismic experiment. Of course, you'd need to ram something the size of Triton into Neptune to get the kind of seismic energy you'd need...

-the other Doug

I think there is a much better chance of there being a defined "surface" within Uranus and Neptune than within Jupiter and Saturn. According to current theory, the former are "ice giants," with massive amounts of water ice under high pressure surrounding rocky cores. The latter are made primarily of hydrogen all the way down to the cores, which are under such intense pressure that they exist in a semi-solid metallic form.

Phase change is a quirky thing; it's affected by all sorts of things, including temperatures and pressures. And phase changes might look dramatic, but still not consist of anything "solid" enough to support the weight of a lander (especially at the gravity massive Jupiter exerts).

For example, have you ever flown in an airliner? From about 10 km up, it becomes very apparent that the lower cloud layers "float" at the upper boundary of the thickest part of the atmosphere, looking rather like soap suds floating on the surface of water. I'm pretty certain, thinking back to my college meteorology course, that this boundary depends upon phase changes (mostly of water) to define it. It's a rather solid-looking boundary, and while the air below this boundary can sometimes be crystal-clear, it is often (depending on humidity and particulates) as concealing as a muddy stream. It really looks, to the eye, like solid objects ought to be able to sit on this boundary, or at least float at it. And of course we know that this really isn't the case.

The point is that phase changes, especially from gas to liquid states, don't always generate as much structural strength as they "look" like they should. I'm pretty sure that, within Jupiter and Saturn, the boundary between gaseous and liquid hydrogen occurs at such a high pressure (and, therefore, density) that, while it may look significant "to the eye" (so to speak), it really would not present a surface upon which a falling object would be arrested and supported against gravity.

Uranus and Neptune, though -- they're smaller and contain more water and less hydrogen than the two gas giants, and thus might feature far more drastic compositional changes as you descend towards their cores. Pressures and densities are still astounding compared to Earth standards, though, and "hot ice" surfaces below mostly hydrogen atmospheres are distinct possibilities. However, the pressures at such surfaces might be so vast that nothing our current technology can even conceive of would be "robust" enough to reach them intact.

-the other Doug

Exactly what I've been thinking. The annulus around Victoria is obviously quite altered; it is quite dissimilar to the etched terrain that surrounds it on all sides. And it is arrayed around the crater exactly as an ejecta blanket would be arrayed.

I'm afraid I really don't buy the buried/exhumed theory for Victoria, either.

-the other Doug

From the way Steve Squyres nearly cried when he saw Oppy in the MRO image of the Victoria area, one might wonder just *how* close Steve was to his creations before they left for Mars...

-the other Doug

Yes -- I was always impressed with one of the means by which original Shakespearian pronunciation was deduced.

In one of the plays (I don't recall which one, offhand), one of the characters is asked for a reason for something. His reply is that "reasons are as plentiful as nuts in a fruitcake."

When someone finally connected the contemporary pronunciation to the present-day Scottish burr, they realized that "reason" must have been pronounced with the first vowel resembling a long A more than a long E (as in the current Scots accent). So, the line would have sounded like "Raisins are as plentiful as nuts in a fruitcake."

Thereby, a Shakespearian pun shed light on the pronunciation of English in those times.



-the other Doug

I just voted for the Cassini image, and it's comfortably overtaken the gold image for the moment, 6254 to 3900. The woodpecker is out of the running with only 333 votes.

-the other Doug

p.s. -- actually, I'd be interested in seeing a cover based on the article "The Early Earth" that's also running in the upcoming issue. DVD

My roommate keeps insisting that HiRISE ought to be able to find both Helium and the vast thoat herds that must be wandering around down there. I just don't have the heart to correct him anymore...

-the other Doug

If I have my math right, that works out to 7:44 pm Central Daylight Time on Wednesday, October 25 for us here on the other side of the pond...

-the other Doug

Well... remember, Sojourner was programmed to circle the lander platform in the event of comm loss. It's possible (if not likely) that the Little Toaster might have operated for quite a while after the lander's batteries died, in which case she might have drawn a rather obvious circle around the lander.

Of course, it will be next to impossible to tell from such a feature (if it *is* visible) exactly how long Sojourner orbited her poor, dead parent... And from what I understand from earlier discussions, it's literally impossible for any of the the current orbiters to even try to contact Sojourner on her UHF link, on the extreme off chance that she's still working after all these years.

-the other Doug

And, for sure, we can feel free talking about Jason "behind his back" in this particular forum, since he never, ever reads the Mars fora... *grin*...

-the other Doug

Yah sure, you betcha!



-the other Sven... or is that Ole?

I still have a 17-year-old videotape of PBS's presentation of "Neptune All Night," when they covered the Voyager 2 Neptune encounter. With a member of Firesign Theater no less, doing his character of George LeRoy Tirebiter...



-the other Doug

I was in grade school during the Mercury missions, and we all gathered in the auditorium and watched John Glenn's launch in February of 1962. Because the launch was delayed several times, we were gathered several times, and the last time, when the launch actually occurred, we all got there just before he went off.

The launch of Apollo 7 was 'cast through my junior high school's PA system, as well... they thought more highly of the space program in the schools back then.

-the other Doug

Here's a question:

If this model is correct and Venus originally had a moon that escaped -- what happened to it?

I don't suppose it's possible that this original Venusian moon that escaped is now called Mercury?

-the other Doug

I see the scene playing out more like this:

"What is your name?"

"Arthur, King of the Britons!"

"What is your quest?"

"I seek the Holy Grail!"

"What is the resolution of the MER Pancam?"

"What -- before or after onboard binning?"

"I... I don't know that! AAIIIEEEEEEEE!!!!"



-the other Doug

In my little home network, here, my computer is named HAL. When I got an add-on hard drive to accomodate the large files I was stacking up, I named it HAL Jr.



-the other Doug

A tiny bit of the water at the lunar poles might well already have been transported there from Earth. Hundreds of pounds of water were released by Apollo vehicles and equipment, both on the surface and in lunar orbit. The LM, for example, cooled its systems using ice-encased sublimators. The PLSS backpacks the astronauts wore were also cooled using ice sublimation. Heck, a water seal leak on Apollo 15 resulted in the wholesale dumping of about 30 liters of water onto the surface.

While most of that water was likely lost to space and has been pushed out to the far ends of the solar system by solar winds by now, a little of it must have migrated to the always-cold portions of the lunar poles.

So, just a little tiny bit of the polar water has already been imported...

-the other Doug

Also, recall that the rock horizons, once they are laid down, are then at the mercy of tectonic and isostatic movements of the crust in the region. For example, let's suppose that Meridiani was once the site of a moderate-sized sea. Remove a vast majority of the water by evaporation (and assume that the water has now moved, via atmospheric transport, to the poles), and a rather great weight has been taken off of the rock beds at Meridiani and placed, instead, at the poles. The crust at the poles will tend to sink under the weight of the added ice, while the crust at Meridiani will tend to rise a bit with the release of the water's weight.

Or, assume that the large patera formation in Meridiani Terra was built after the Meridiani Planum rock beds were laid down, and the pressure of the magma underneath the Terra region pushed the entire region (including the Planum region) upwards, and then dropped it down as it escaped and was piled onto the surface.

In either of these cases, the rock bed horizons may simply follow the surface levels, shifting as the underlying crust shifts (rather as a rug will conform to the surface of the floor, even if the floor shifts underneath it). Moving up and down in elevation will make no difference as to where in the strata the surface is located at any given place.

For movement along surface elevations to move you up and down through the rock strata, you have to have some deflation or erosional process occurring that has caused the elevation changes. Literally, you have to have a process that removes some of the layers to allow you to descend within the strata.

I'm not saying that moving downward in elevation wouldn't take you deeper into the strata. I'm just saying that you need to prove that the elevation change is a result of upper layers being stripped away before you can make that assumption.

-the other Doug

Gee -- one stupid planet disappears behind the Sun, and most of y'all have nothing to talk about...



-the other Doug

I have a funny feeling that a "nearby" hypernova would first make itself known by how our upper atmosphere would flouresce so entertainingly -- as it blew off into space.

Not much time, in those cases, to re-route the entire industrial output of every nation to create an ark that would be able to save only a tiny fraction. Even if people could do such a thing, I dunno that there would be time.

-the other Doug

Cool -- cars and quonset huts and even a propeller-driven light plane taking off. Would that Mars actually had enough atmosphere for any of that...

-the other Doug

I'm not sure how to say this, but it has to do with the past, and it has to do with the future. So it belongs here.

We're all of us contemplating how we're going to react when one and then the other of the MERs die. But y'all are lucky --- as am I -- in this case. Because while the MERs will die, there will be thousands of exciting images coming in the next few years from MRO. And there will be new landings by Phoenix and MSL, which will provide all of us with fine armchair exploration experiences for many years to come.

When I was growing up, I followed Apollo like most of y'all follow the MERs. I vicariously experienced those first explorations of the Moon just as y'all vicariously experience these first robotic explorations of Mars. I looked forward to each new mission, soaking up the geology needed to understand the selenology that was happening. Examining each new landing site with all of the resources available to a teen-ager in the late '60s and early '70s, looking forward to each new landing, each new traverse.

But as of the end of 1972, no matter what might have been promised or speculated, it all went away. No more lunar exploration. No more visits to the magical place I had visited in spirit, if not in body.

We will all be able to follow the coming Mars explorations and can visit Mars again and again, in spirit if not in body. And that's a very good thing.

But just imagine if, once the last MER died, that was it. No more new vistas. No more new hills, rocks and craters. No more new insights.

Just a part of your soul that will always live in the past.

Just imagine that for a few moments, and then -- welcome to what my last three decades have been like...

So -- we're all lucky that these explorations of Mars will continue, with new vistas to see and new secrets to unravel. Let's all be sure we thank our various gods for that luck...

-the other Doug

Yes, that explains a great many things, John. I may occasionally disagree with your assumptions, but I always find your logic impeccable.

-the other Doug

Then again, you could always go the route of The Onion, a popular humor newspaper here in the U.S. Their re-telling of history might be appropriate:

"Holy f****** s***! I'm standing on the f****** Moon! Do you f****** believe this?"



-the other Doug