Well -- that certainly settles the question of the landing site, doesn't it? Where does such a beast land? Wherever it wants to!



-the other Doug

Oh, gods and goddesses -- I can hear the news commentators now:

"The new Mars Rover, Goofy, landed on Mars today..."



-the other Doug

Doubtful. According to the opinion of someone who ought to know, one of the more famous Vulcans of anyone's acquaintance couldn't sell fake patents to his mother...

-the other Doug

You know, it was impressive when Chang'e and Kaguya both worked exactly as designed, no major malfunctions or problems. But for Chandrayan-1, with a much more challenging early mission profile (delivering an impact probe, relaying its information perfectly, and the impact probe itself working perfectly), and doing this all for the first time with no issues to speak of -- that is very, very impressive.

Hats off to all of our new partners in crime!

-the other Doug

Actually, while I was mostly kidding about any attempt to find and salvage the Apollo 13 RTG fuel cask, it occurs to me that the only really huge factor against such an undertaking is the rather large portion of ocean floor you'd have to comb trying to find a cask that's less than a meter long and less than 30cm in diameter. There wasn't much tracking of the LM for the last 15 minutes or so before it hit the atmosphere, and the random break-up of a tumbling LM could have imparted a wide variety of different vectors to the cask as it separated from the vehicle.

The other factor that makes it less useful to try and recover such a resource would be the fact that it was produced a good 40 years ago, now, and has been sitting in its current location, in its current form (a rod about 35 to 40cm long and about 5cm in diameter) for the aforementioned 38.5 years. While I imagine it could be further refined to separate out the remaining Pu-238 from the decay products, that process would look a lot like the original production process, wouldn't it? A production process that's shut down for now.

However, if that Pu-238 was in a known location, and if it would be useful for future RTGs, we have the technology to retrieve it. And I bet that the retrieval costs would be less than (or at worst comparable to) the cost of producing the same amount from scratch. And, of course, if you don't have the means of producing more, then the comparison becomes a divide-by-zero error...

Seriously, I know that the ALSEP RTGs had all run down far enough by the time an attempt was made to re-start them in the '90s that none of the five stations responded (assumedly because the power levels had dropped to the point that the transmitter/receivers had shut themselves down). Just how useful would a 40-year-old Pu-238 rod be for future RTGs?

-the other Doug

Give Ken the Kewpie doll, we have a winner!

-the other Doug

Oh, this isn't a bomb, it's not weapons-grade Pu. It's RTG-grade. It wasn't launched in an RTG, though -- it would have been transferred into an RTG at its destination. It just never got to its destination.



-the other Doug

I know where you can find a few pounds of Pu-238. It's in a graphite cask that ought to be no more than a little singed around the edges.

Oh, and it's located under some 7 miles of ocean, near (perhaps in) one of the deepest ocean trenches in the southwest Pacific. And it's been lying on the ocean floor for a little more than 38 and a half years. So, I guess maybe it might be a little more depleted than we'd want, eh?



-the other Doug

As for my own reaction to this version of NCC-1701, I was afraid they were going to try something like this. After they made Archer's Enterprise look a lot sexier than the original series' starship, I was worried that any TOS prequel movie was going to try and make the Enterprise look sleeker and higher tech than Kirk's ship.

As far as design goes, it's like a company was making Italian sportscars for generations, and for one single generation decided to retrofit all of their products to look like a 1970 Volvo.

It's possible to make the original TOS version of a Constitution-class starship look and move really great without damaging the original design -- they did it with CGI in the "Mirror, Darkly" two-parter near the end of ST:Enterprise's last season. I'm unhappy that some guy has decided to remake the Star Trek canon in order to produce Starfleet 90210.

Sigh.

-the other Doug

Ted?

I find your lack of faith disturbing...



-the other Doug

That's all we really wanted to hear -- that we had a successful comm pass and that Spirit is still communicating with Odyssey. The details can wait -- what we wanted to know is the girl hasn't died!



-the other Doug

Sorry to resurrect an old thread, but at the beginning of this thread (back three and a half years ago), it was noted that the MSL descent strategy (the skycrane maneuver) was dependent on the success of ground tests planned for the summer of 2005.

The fact that the skycrane maneuver is still the official plan for MSL's EDL (emphasis on the L) tells me that those tests must have been successful. But there was not a single post about the results of those tests in this thread, or in any thread that I can recall.

Does anyone know how the tests were conducted, and what the actual results of those tests were? Was the descent stage design adjusted due to those results? Are there any areas of concern that were addressed in design after the tests, and if so, are there things we ought to be looking at during the descent to make sure those areas of concern were properly addressed?

Very curious...

-the other Doug

No... but perhaps, some night this week, everyone can co-ordinate to point their faces at Mars, take a *really* deep breath, and blow as hard as we can...

-the other Doug

Thank you, Dan. That summed up *perfectly* a lot of what I've been feeling about this mission. I know I still get goosebumps thinking about that image.

-the other Doug

I am in awe of the rover handlers. The MERs were designed in such a way that continued power levels at 300 whrs or below was considered death. And yet, here we are with power levels less than a third the level that was designed as the absolute minimum to sustain a MER at even base survival levels, and we're still thinking "Hey, just a few more days, old girl, and there will be more sunlight. We can get through this."

Absolutely incredible.

-the other Doug

It's a sad/happy day. It helps a little that we all knew it was coming, and we all knew it was going to happen right around this time.

Many, many amazing memories for me from Phoenix.

Satisfaction that this type of lander finally made it, nearly a decade after MPL really tearing my heart out.

Intense emotions during EDL. I *really* wanted this one to get through.

Fascination at what small-scale polygonal crust looks like from the surface, and in general fascination over what yet another distinct part of Mars looks like.

Pure delight at the OM and AFM images.

Extreme frustration over the inability of TEGA to get an ice sample. When the mission started, we had Jim Garvin on TV stating in awed, hushed tones, "not only do we think we're we going to find water ice, we're going to reach out and taste it! Can you imagine what we can learn from that???" And yet -- not a single taste of the water. Extreme frustration...

All in all, far more wonder than frustration... but t'would have been even more wonderful had we actually managed to taste the ice.

-the other Doug

For a moment, it sounded like you were citing an EDIT spacecraft. I figured it out quickly, but... the concept of an EDIT spacecraft is interesting. Here's a potential mission description:

"The EDIT spacecraft will be sent to a variety of celestial targets that have already been visited by other space probes. EDIT's mission is to adjust the data returned by these earlier missions to make them conform with our own theories."



-the other Doug

The MER Navcam lenses (esp. Oppy's) have dust accumulations ranging from light to very heavy -- Oppy's are quite occluded on the right sides of the images. However, this isn't a result of general dust accumulation, it happened almost entirely during the global dust storm (which also deposited dust onto the "protected" optics of the mini-TES instruments on both MERs, enough that it might possibly render the devices useless).

I think there's a difference between designing optics to remain "as clean as possible" during normal accumulation cycles and designing dust-storm-proof optics. I'm positive that MSL's cameras are good for the former, but doubt they're designed to handle the latter.

-the other Doug

Oh, sure, I knew you were trying to give a basic odometer reading. I guess I was asking for a trip odometer, as well...

-the other Doug

...which implies that, if you had CRISM data of fine enough resolution, it would aid a driveability analysis in Meridiani Planum and other similar landforms.

Thanks everyone, especially Tim and Mike, for explaining and illustrating the mechanism I was looking for. Quite obviously, this theory wasn't something that occurred to me before anyone else... -- not that I was arrogant enough to think so. But it's nice to see that there is a good, solid mechanism underpinning the observation.

-the other Doug

I have a theory. There are a lot of blueberries in the pavement where the ripples are sparse and tiny. Out where they start looking like a dune sea, the ripples seem to be emplaced directly onto the top of the sulphate-rich bedrock. There does not seem to be a layer of blueberry paving between the ripple bases and the exposed bedrock out in the extensive ripple fields.

I think the surface around the landing site and Endurance was derived from a blueberry-rich strata, laying down a bedrock-capping pavement which by some mechanism inhibits deep ripple formation. As you move south, the land rises and the near-surface bedrock layers are blueberry-poor, no capping pavement is generated, and ripples form bigger and taller, growing to almost completely cover the bedrock onto which they are directly emplaced.

Near large craters like Victoria, the local soils surrounding the crater are derived from the geologically rapid erosion of the ejecta blanket, and all of the ejecta nearest the crater is derived from lower, blueberry-rich strata. Thus, in the soils right around a Victoria-sized crater in this area, a blueberry pavement forms and ripple creation is inhibited.

I'd feel better about this theory if I could think of a plausible mechanism by which the blueberry pavement inhibits ripple formation...

-the other Doug

Is it possible to annotate in some manner the route map with ticks or something for every full km traveled since Oppy's departure from the Victoria rim? I mean, we know we're looking at a trip distance of some 15 to 20 km, it might be nice to see the kilometers falling behind us as we make our way along...

-the other Doug

Found and took a detail of the piece of Tsiolkovsky's floor that I referenced. It was taken using a Hasselblad with a 250mm lens (I believe) from Apollo 17's CSM. It's not from the SIM bay panoramic or mapping cameras.



Actually, the more I look at this detail, it appears to me that the cone-shaped strucure is related to central peak materials and the scarp that borders the darkened regolith patch may have been the source of the fire fountains (if that is indeed what is causing the darkening). Hard to be sure, of course.

-the other Doug

I have obviously only read the abstract linked in the previous post, but I'll take a moment to remind y'all that crater counts can be misleading. On lunar mare surfaces specifically, regoliths containing a higher-than-normal admixture of basaltic glass beads tend to have a higher erasure rate of smaller craters, leaving older surfaces *appearing* younger when age is measured only by crater counts.

On the nearside, most of these types of terrain are darker than the normal mare regoliths due to admixture of black volcanic glasses (assumed to have been formed in fire fountain eruptions), though some areas are tinted other colors based on impurities and slight constituent alterations in the glasses' source magmas. Some glasses are red, some are orange, some are purplish, some are green. But a vast preponderance of the devitrified fire fountain glass beads seems to be a deep black.

I would be interested in knowing which areas are being observed by Kaguya, and what the relative colors and albedo of the regoliths are. For example, there is a very dark patch of mare floor fill in Tsiolkovsky, with what appears to be a small cinder cone or dome-shaped vent sitting in the middle of the dark patch. Sure looks to have fewer small craters than the adjacent lighter mare floor, too. But it seems possible (if not likely) that this patch in the Tsiolkovsky floor is roughly the same age as the adjacent mare surface, and (like the dark soils along the Serentitatis basin's east rim) have fewer smaller craters because the soil is "softer" and retains craters of that size range for shorter timeframes.

I'll be really interested in seeing the types of mare surfaces they were looking at when the authors came to their conclusion in re surface ages. I don't insist they have to be wrong, I'd enjoy it if they're right; I'm just bringing up one of the ways in which lunar geologists have been proven wrong about crater-count-derived surface ages in the past.

-the other Doug

The Lunar Orbiter spacecraft used motion-compensation built into the internal camera platform to obtain non-smeared images during low-orbit photographic operations. This system failed on L.O. 1 (a sensor that measured the rate a which the surface passed beneath the camera failed), and so most of the images from its low orbit are hopelessly smeared.

As for using physical movement of the entire spacecraft for motion compensation, the first example of that I can recall was on a manned spacecraft -- Stu Roosa used the technique after the Hycon camera failed on Apollo 14 so that he could acquire needed planning imagery for the eventual Apollo 16 Descartes landing site. In that case, he set the CSM into a special "orbital rate" mode to keep it aligned with a specific point on the lunar surface and took the photographs with a Hasselblad camera fitted with a 500mm lens.

-the other Doug