As I recall, the bounce marks where the verniers disturbed the wall of Surveyor crater weren't very visible during A12 operations, since they were on a wall of the crater that was under a very low sun angle. They are much more obvious under a high sun angle. I remember seeing them identified in S-III panoramas of the crater wall taken while the sun angle on the wall was pretty high. (That panorama might well be in "Exploring Space with a Camera," for those who still have a copy.)

The LROC image of the area shows the wall where Surveyor bounced under a very high sun angle. You'd think they would be pretty obvious in this image.

-the other Doug

I agree, those things weren't in the LO images of the area. But while these *may* be the tank, they don't *have* to be.

First off, note that we see five apparently man-made objects that are bright and reflective. There is the LM descent stage, the Surveyor, a piece of the ALSEP (likely the top of the central station, though it could possibly be the skirt around the PSE), and the two items that people are saying might be the retro tank. ("Tank" being a bit of a misnomer -- it's the casing or shell from a spherical solid rocket motor.)

If you recall the liftoff movie from Apollo 15 (and verbal comments from other crews), big pieces of thermal blanket (the MESA blanket, for example) have been known to blow out and away from the LM upon APS ignition. On Apollo 15, a big blanket narrowly missed knocking over the ALSEP central station and flew on downrange at least another half a kilometer or more.

It's just as likely that the bright spots to the north of the Snowman are thermal blankets blown out from the LM as it is that they are pieces of Surveyor's retro rocket. I'm not saying these spots are not the spent rocket casing -- just that there is an alternative explanation that is just as likely. So... don't stop looking for the spent motor, guys! It might be somewhere else.

-the other Doug

p.s. -- it might be instructive to search other landing site LROC images, especially that of the A15 site, to see if we can find other examples of ejected thermal blankets. Seeing what they look like, how far they were blown away from the LM, etc., might shed some light on what we're seeing here. DVD

If I remember my high school French from 37 years ago, I believe it runs:

Janvier
Fevrier
Mars
Avril
Juin
Julliet
Aout (sorry, don't have an easy way to add diacriticals here)
Septembre
Octobre
Novembre
Decembre

And the days of the week are:

Lundi
Mardi
Mercredi
Judi
Vendredi
Samedi
Demansche

Spelling could be atrociously wrong, of course...

-the other Doug

I would never, ever seriously suggest such a thing. But for the only mission where the TV camera wasn't able to transmit any panoramic images from the surface... to keep the idiots and such at bay, they really need to get this image soon.

-the other Doug

A little curiosity from someone who doesn't have the tools to be able to plot LRO's orbit, etc...

All of the images I've seen seem to be taken under mid- to late-afternoon sun angles. All of the images I've seen at low sun angles from other probes (especially LO) were, if memory serves, taken under early- to late-morning sun angles. Is this being done purposely by LRO to vary the lighting angle from other resources? (If so, it makes it that much harder to do photo comparison for detection of new craters.)

Also, why the heck have we yet to see the Apollo 12 landing site, when we've seen multiple takes on a couple of the other Apollo sites? Is it possible that A12 visited a *different* Surveyor than the one advertised...?

-the other Doug

Um, yeah -- my swear jar overfloweth!

The thing that strikes me, though, is that you could land a LM (or a Constellation lander) on the floor of that crater! There are lots of places that are flat and smooth enough for a vehicle to land. You'd have to be real careful where you walked and/or drove, but it could easily be done. And would be incredibly spectacular!

And check out some of those rocks! There are rocks in there (and especially on the rim) that make House Rock look like a pebble!

-the other Doug

"My God... it's full of wheel lube!"



-the other Doug

The real problem is that, with outer planet missions, you play transit time against approach velocity. To get out to Uranus or Neptune in 10 to 15 years, you have to be traveling pretty fast relative to your destination by the time you arrive. You can design a trajectory that results in a much lower approach velocity, but such a trajectory will take 30 or more years to get out to the farther reaches of the System.

So, unless you want to launch a probe that will be managed by multiple generations of PIs, flight support personnel, etc., you have to deal with taking out a pretty hefty amount of velocity upon arrival. This will be the case right up until we can design a constant-acceleration propulsion system and we can accelerate for half of the outbound trip and decelerate the other half. When we eventually develop such a propulsion system, we'll be able to travel to Mars in weeks and the outer planets in months.

Until then, though -- you gotta slow down when you arrive, so you need to carry enough fuel and/or aerobraking equipment to do so. And, the film 2010's fictional flight planning aside, you gotta have enough fuel to raise your periapsis out of the atmosphere after a primary approach aerobrake, and the amount of fuel plus the mass of the aerobraking equipment required for the aerobrake vs. the amount of fuel you need to do a rocket-only insertion generally comes out in favor of the rocket-only option.

-the other Doug

Well, I'm home, everything is just fine here. No damage whatsoever right here. I did drive the mile or so down the road to where there were reported touchdowns, found a nice neat line of uprooted trees (a couple had dropped back down onto adjacent homes, breaking them up a bit), found a local record store closed for tornado damage where the owner reported to me that the roof had lifted off the building and then settled back down -- you could see the front wall of the building bowing out towards the street near the top. Tons of store windows blown out, glass all over the roadway, uprooted trees trees blocking streets, etc.

Apparently, observers in the top stories of the 70-some-story IDS Tower in downtown Mpls saw the funnel (by this time not on the ground) go by, with entrained debris *above* them at their 600-some-foot vantage point. As the funnel collapsed completely, they watched the debris fall out of the sky and onto the streets below. (Sorry, Dan, no cows -- just tree branches and such.)

Overall, the damage was limited to a few very small areas where the twisters actually touched down (on the ground or onto the roofs of buildings), and there have been no reported deaths or serious injuries. I even have power, the cable never went down, etc.

And Dan -- first off, if I thought there was *any* chance I could get a pic of a tornado, I'd be all over it, bosses or no bosses. I have been within a few miles of tornado touchdowns several times in my life, and have never, ever seen a funnel on the ground. It's one of the things I'd like to be able to do before I die. Unfortunately, the actual tornado activity was a good 10 miles away from my workplace, and there was just no way I could sneak out of the building and go looking for it. Especially since no one knew there were actually tornadoes touching down until a good half-hour after the event.

All in all, sort of a fun day!

-the other Doug

Hey, guys -- spent a good hour in the basement of my call center here in St. Paul, waiting out tornado warnings. (Actually, spent a half-hour downstairs, got back to my desk and another warning was issued, so trundled right back downstairs for another half hour.)

Nothing hit right near my workplace, but apparently there were tornado touchdowns within about a mile of my house in Minneapolis. I won't be home for another 90 minutes or so, but talking to a friend in the same area, it appears that there was not much damage in my neighborhood.

I'll let y'all know if my home is still where I left it... later. (I wish there was a smiley for the emotion "whew!")

-the other Doug

Yep, that's the one -- I see that Surveyor I was actually imaged by LO1 and LO3, with the LO3 picture the better of the two.

I remember the image from the classic "Exploring Space with a Camera" by Edgar Cortwright. Here's the image I recall, a three-shot zooming in on the SI site:



Many of my early Surveyor image memories come from this book.

-the other Doug

Also, dual-probe missions have increased the science return from their given opportunities. Primarily, we've been able to target the two probes on dual-probe missions somewhat differently, using the same instrument suite to look at different locations. That was actually done on Mariners 6 and 7, Vikings 1 and 2, Pioneers 10 and 11, and Voyagers 1 and 2. There were also, of course, plans for the Mariner 3/4 and 8/9 missions to use the same instrument suites to look at different locations.

Dual- and multi-probe missions, though, also give you the opportunity to send probes with different instrument suites to the same location. I can imagine this kind of approach would work very, very well for outer planets missions, where your orbiters all have shots of their own at observing the primary planet and each of its moons. Once you finish your pre-planned primary mission, you use the results of one instrument suite to define how the rest of the instrument suites are used on each extended mission.

I'd think you'd have more flexibility, as well -- imagine if you had 4 mini-Cassini's at Saturn now, one with SAR and general imaging, one with high-resolution multi-spectral imaging, one fields-and-particles vehicle, and one with VIMS and additional spectroscopic analyzers to look at the chemistry of the planet, rings and moons.

Now, each of these guys would be on their own mission orbits, with the SAR probe staying out near Titan a lot. One suite would follow up the results from the other suites. Perhaps the vehicle with all the spectroscopic analyzers could be designed a little mechanically tougher than the others, so you could dive it through plumes and the vaporous edges of rings.

Figure that each of these spacecraft could share designs (and manufacturing, etc.) for a common physical bus, common attitude control and propulsion systems, common data handling and communications systems... You'd be developing maybe 20% more sensor systems for the various instrument suites, but your designs, fabrications, engineering, etc., can actually get into savings-of-volume. If you can spend maybe 50% more on your multiple spacecraft than you would on a single Flagship mission, but spend only 60% of what you'd currently spend on launch costs, then it tends to even out. You get more science, a more flexible mission, and the ability to follow up on discoveries by some instruments with detailed analyses by others, without hauling all of the rest of your instruments along on your detailed analyses.

Does that kind of mission architecture sound exciting to you? 'Cause it sure does to me!

-the other Doug

I think a 5-fold to 10-fold reduction in launch costs would result in more twin-probe or multi-probe missions. It costs maybe half-again more to produce two new probes than a single probe (if you take the MER project as an example). A third probe adds quite a bit less to your costs, as does a fourth, etc.

So -- if you can design four probes that are nearly identical (with perhaps some variation in their scientific payloads) and launch them to the same destination for the same cost as what you'd pay today for a single flagship mission, you can get a potential for a lot more bang for your buck. I can envision flying a really solid NetLander mission to Mars this way, or sending a flotilla of four to six Jupiter-system probes, each with its own unique program to execute, and each perhaps half as capable as a flagship probe.

You're still talking flagship mission funding, of course, and so only looking at seeing such multi-probe missions once a decade or so. Even so, in the meantime, you'd at least be able to spend a little more on Discovery-class mission spacecraft and a little less on their launch costs. In other words, reduction in launch costs is always a good thing, but I think it'll have more of an impact on flagship-class planning than on intermediate-class missions.

-the other Doug

I'm not sure what you mean by "resolvable," Steve. It's not like we're able to resolve a star disk image with a transit visible as a blotted-out circle within it. But I would imagine that the "resolution" in this regard would be the same as Kepler's overall ability to detect a planetary transit. A moon would have to be the minimum size necessary for Kepler to detect it, all by itself, as a transit event. So if Kepler can't detect the dimming of a star's light caused by the transit of a Callisto-sized planet, it ought not be able to detect the additional dimming that would occur with a Callisto-sized moon as it would appear in the first frame of 'squid's excellent illustration. And also, therefore, ought not be able to tell the difference between the first and second frames.

As I understand it, Kepler can detect down to about an Earth-sized planet, correct? Then I would have to think that the smallest gas giant moon it might detect would have to be at least as large as the Earth.

Another very interesting thing, though -- any planetary body with a ring system will block more or less of a star's light depending on the angle the ring plane presents to the viewer. I can well imagine that some percentage of the planets Kepler will discover may indeed have ring systems, and that these ring systems may not always present the same angle to us here on Earth during every single transit. It will be very, very interesting to see how fast the investigators suspect they're seeing ring systems in some of their results...

-the other Doug

And, of course, there are five Surveyors on the surface that ought to be visible to LRO's camera. We'll get Surveyor III when the A12 site is imaged, but I'm more looking forward to seeing SI and SVII. We've seen a decent image of SI on the surface from one of the early Lunar Orbiters (LO2, IIRC); I'd like to compare that image with an LRO image. And it will be very, very useful to see the SVII site from orbit at LRO resolution, since we may someday want to land manned or unmanned probes in similar terrain; it'll be nice to be able to characterize "safe" landing areas in such apparently rugged terrain.

-the other Doug

All of these worlds are yours

except Europa. Attempt no landing there.

Use them together.

Use them in peace.


-the other Doug

"You may be wondering why a Terran from country of Nigeria am contacting you on Gliese 581."



-the other Doug

"Here comes Mr. Bill's sand trap...!"

"Oh, Nooooooooooo...."



-the other Doug

I thought the theory here was that the northern plains (where Oppy landed) are blueberry-paved deposits formed as you described, with the deflation of a good meter or so of soft sulfate-rich sandstone that halted when the freed concretions provided an anti-aeolian "armor." The remains of the sulfate rock that was blown away composes the extensive ripple structures to the south (through which we're currently traveling). This terrain didn't have as many concretions buried in its sandstone layers, and so never developed the full armoring. Instead, ripple structures protect the remaining sandstone paving in the ripple fields from further erosion.

-the other Doug

Yes.

Seriously, both functions are probably at work, here. We really don't have the best handle on relative impact rates (as sorted by size and class of impactor) at Earth v. Mars, but it's a decent bet that there is a higher density of potential impactors as you approach the main Belt. And while it hasn't been proven yet, it also appears that this particular hunk of metal was buried for a long time and has since been re-exposed due to the aeolian deflation of the upper rock layers at Meridiani. That has a similar preservation effect that you see with meteorites that land in Antarctica, are buried in ice for very long periods, and are then thrust back to the surface via one or more of a variety of processes.

-the other Doug

Ummm... let me get this straight. VEX ops are pre-planned four months in advance and nothing can be changed in those pre-planned ops plans? So that any follow-up on transient phenomena literally cannot take place for at least four months?

If that's the case, then we truly don't have a resource at Venus that can do anything at any given time except its pre-planned program, which will always be a good four months out of date. I guess we can take "respond to transient phenomena or rapid changes in environment" off the list of VEX's abilities. (I know, it's never been a claim of the project.... but, as Doug says, the whole thing gives me rage.)

But, to be fair... with what do I compare this? Can Cassini's op executions be changed after they are loaded into the spacecraft? If so, how quickly? How fast can Cassini respond to some changing circumstance? How about Hubble? We know Hubble had been packed solid with use requests and that it was still capable of being re-tasked to get Jupiter images within a week of the first detection of the impact on old Jove.

Maybe we're all just too used to ops plans like those for the MERs, where what we do tomorrow is highly impacted by what happened today. Obviously, many NASA probes (especially those in the outer system) don't have that kind of operational flexibility, either. So... how does VEX compare to other planetary probes in terms of being re-tasked?

-the other Doug

Yep -- ESA should have a "no bucks, no Buck Rogers" talk with the European scientific community. Remind them that they can do whatever they want in terms of funding the instruments, but without a ride to the planet of their choice, they'll never be able to use them. And that, with such pathetic data flow imposed upon ESA by the PIs and no apparent interest in outreach by the scientific community, the rides will all go away -- sooner rather than later -- unless something changes soon.

While I am 100% behind scientific research, it is very true that too many of these people have been living in ivory towers for so long that they don't have a clue how things work out here in the Real World. The educators need an education.

-the other Doug

Well, we have a lot of Apollo 15 and Apollo 17 pan camera high-resolution imagery of the Taurus-Littrow site, so we ought to be able to identify any new crater in the LRO images.

This might be a good situation for doing a photographic subtraction in Photoshop. If you can get roughly similar sun angles, a subtraction of the LRO image from an A15 or A17 image of the same area would highlight any major changes to the terrain. In fact, that's something we want to do in a variety of areas, I think -- it will let us get good empirical data on the cratering rate (down to sub-meter cratering events) over a period of nearly 40 years.

-the other Doug

Actually, the impacts from known hardware are useful to observe. We can calculate pretty accurately the mass of the impactor, the speed of the impactor at time of impact, and the trajectory.

Remember, our theories on impact processes are based primarily on theoretical physics, with experimental results limited to very small impactors in laboratory conditions. Exacting measurements and analyses of relatively large-scale impacts (at least, larger than can be achieved in a lab setting) are valuable to the testing and verification of our theories on how impact processes actually work.

-the other Doug

If BI has been eroded by chemical means, is that not something of a confirmation of a highly acidic water table in the area (admittedly, long ago)?

-the other Doug