Feel free to impress me with a mnemonic for the moons of Jupiter. There were 62 the last time I checked, but it looks like S/2000 J11 and S/2003 J1 through J23 don't have names yet. I'm having a hard time doing much with MAATIEGCTLHLEIPHAIETCCPKMSCEKOTEHPEASA myself

I'm a little confused; this article says that Mike Brown was on the committee, but Brown's web site says he isn't an IAU member and can't vote, and other articles on the web quote him as being somewhat critical of the definition. What's the real story?

I guess this is one of those "if you have to ask, you'll never know" things, Jason. Kids memorize the names of the planets, but if there were 50 of them to memorize, they won't be able to. I don't know the names of all of Jupiter's moons myself (assuming they all have names.)

At these polar latitudes I don't think the sun ever sets at the season when they form. You would have to explain why they don't happen at 2 PM and 2 AM (for imaging on the other node) local time when MGS goes over.

As usual, media coverage and summaries state a lot more certainty than many of us have. If these sprays are so large, how come we've never imaged one with MOC after years of trying?

Interesting read, but I was a little surprised by his claim of a large number of KBOs that would be planets by the hydrostatic definition. He seems to feel that anything over 400 km in diameter would meet that criterion (presumably if it were mostly ice.) I really think that having >50 "planets" is simply non-viable, and I'm not sure why he poo-poos the simple idea that anything larger than Pluto would be a planet as so non-scientific. Oh well, I guess this is why I'm not an astronomer.

There are some potentially-useful line drawings in some of the papers linked to from http://www.pxi.com/clementine/publications.html -- especially the last one on that page. No three-views or dimensions that I saw.

Art's a regular there, so I'd be surprised if he hadn't checked them first.

I'll see what I can find.

The barycenter rule is laughable, IMHO. You'd think they could have tried a little harder if the intent was to handle extrasolar double planets in the future, unless somebody had some political agenda to make Charon a planet. I'd have tried to make the minimum barycenter distance some function of the body radii so as to exclude Charon.

I also wonder how well the hydrostatic rule will work in practice around the low end, something we are likely to see either for KBOs or even for the larger asteroids.

Leave it to the IAU to overcomplicate what was a seemingly simple question.

Spacedaily claims that Charon makes the cut as a planet. I don't see how, since the body has to be in orbit around a star. It seems like they are saying that if the barycenter is outside either body (or something like that) then both bodies are planets.

Seems kinda silly to me. Worst. Definition. Ever.

According to the Dnepr User's Guide (http://www.kosmotras.ru/archive2.htm page 64) polar launches are always southward.

I feel compelled to be that pedantic ass who points out that "wherefore art thou" means "why are you", not "where are you". See, e.g., http://www.cjr.org/issues/2003/3/lc.asp

That doesn't sound plausible to me. The primary payload for this launch was BelKA, a Belarussian remote sensing satellite intended for a sun-sync orbit. I think it is true that many Russian sun-sync launches are from Plesetsk, not Baikonur, so it may be somewhat unusual in that regard.

I thought that most of the Sun images were being used only to estimate tau. I can't be sure from http://anserver1.eprsl.wustl.edu/anteam/me...ate_systems.ppt (page 13) if the processing is onboard or not, and I don't know the frequency with which they make these refinements. There has to be some onboard processing to provide coarse initial azimuth, but I'm not sure about fine adjustments.

There's a lot more information in http://trs-new.jpl.nasa.gov/dspace/bitstre...8/1/05-0560.pdf but I haven't read through it yet.

Also see Eisenman, et al, "Sun sensing on the Mars exploration rovers", http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=1035391 if you have IEEE access.

This might have been true for Phobos, where there was some effort planned to make the "1-day drift orbit" period be an integer multiple of the period of Phobos and so produce a close approach on each orbit. I don't think the Deimos geometry would have been much improved, though.

Actually, I doubt this image would have been taken otherwise; it's not really that great or useful an image considering the range (but it probably would have been silly to have not tried it at least once.)

I haven't heard any specific plans to image MRO but I wouldn't be surprised.

I didn't work on this release, and I think more effort could have been spent on it, but when you're banging these things out once a day, there really isn't much time to spend on any given one.

Images in the gallery are raw out of the camera. I tried to make it as clear as I could in the ancillary data what the flipping status is. Obviously the map-projected versions are north-up east-right as one would expect.

We have, of course, been tracking this technology since it was introduced (see http://www.foveon.com). There are two major issues: first, the company was not very forthcoming with samples of and details about the sensor in response to our inquiries initially (we haven't checked for several years, though; they initially were selling entire custom camera setups for studio use, not just the sensor) and the sensor isn't truly electronically shuttered (it's a CMOS rolling shutter design and is typically used with a mechanical shutter). Being CMOS, it is likely also susceptible to single-event latchup (CCDs aren't because they are NMOS). I don't know what the actual noise performance of these sensors is (all they appear willing to say is that they're "low noise"). And there really hasn't been a lot of commercial acceptance of this sensor technology yet; the Sigma SD9/10 is the only DSLR available that uses the sensor that I know of, and I've never seen one. For MSL, we believed that a CCD system was a better choice.

It's also not clear that you "triple" your resolution. A Bayer filter has two green and one each of red/blue for each 2x2 pixel group. With proper resampling, there is a fairly small impact on effective luminance resolution except for pathologically-color-patterned scenes. The MSL cameras will use good resampling and then compress in YUV space, so color artifacting should be pretty minimal for RGB color images. For narrowband color, we may take a resolution hit for some bands, but this mode is mostly only useful for fairly gross spatial characterization of color differences anyway.

You can ask Jim, but at this point I think I know more about the MSL cameras than he does.


Why, so your eyes would try to pop out of your head when you tried to fuse the stereo, like they do with the Viking cameras? A 20 cm baseline was judged to be good enough for the near field. For the far field we will get stereo by moving the rover between frames, as no fixed baseline was large enough. And at any rate, I think the flight baseline will be a bit larger than 20 cm for reasons of the mast mechanical design.


I'm concerned too, but those are the requirements the PI gave us. 3x mission life is the requirement, that's six years equivalent. And we are using slightly more robust materials than your digital camera.


No, of course not, not for a year or more. We'll use whatever camera model is appropriate. Zoomed in there is very little distortion; zoomed out there's a lot.

Yes, this is the only CCD. In some wavelengths (beyond 750 nm) the Bayer filter is essentially transparent anyway. In the visible wavelengths some of the pixels don't return usable signal levels and are discarded. If it were up to me I would leave the filter wheel off, but you can take that up with Jim.

Because the article lead says that the mission statement was "quietly altered". What's "quietly altered" about a complete change of the statement? The implication is that NASA was trying to slip this past, but anybody who's knows anything about the agency's culture would realize that NASA was trying to reaffirm its commitment to aeronautics (which the previous statement said nothing about) and be more general about its science and exploration goals.

This is false and misleading reporting by the NYT. The 2006 strategic plan says NASA's mission is "to pioneer the future in space exploration, scientific discovery, and aeronautical research." That's a completely different statement, not an alteration of the previous one. And I can't even find a mission statement in the 2007 budget request.

It's fine to be arguing about whether we're spending enough trying to understand climate change, but it's
ridiculous to be parsing these mission statements for their intent.

I'm completely with Phil on this one; the NASA mission statements are usually embarrassing pieces of PR hackwork (remember "to improve life here, extend life to there"?) What matters is what the NASA budget request asks for. The FY07 summary says "NASA will also continue to play a major role in the interagency Climate Change Science Program". See http://www.climatescience.gov/ for what that is. And I wonder about the cost effectiveness of the big EOS satellites anyway, especially for studying climate change.

These names were approved by the IAU in 1970. They either didn't have that rule at the time or (more likely) made an exception in this case.

I don't think either of these solutions would work to solve the problem you're describing. You can't determine your location by observing pulsars from a single point with any kind of accuracy. You may be thinking of VLBI, which is used for geodesy on the Earth, but this requires simultaneuous observations from several locations and high bandwidth communications between them.

As to GPS, one of the components of such a system is knowledge of the transmitting satellites' positions. So without a fixed location from which to track them, I think there may be a chicken-and-egg problem if you are trying to get very high positional precision (even on Earth, GPS can't do better than a half meter or so even using DGPS.)

There may be some sort of multiple-satellite, multiple-transmitter solution to this problem, but that would require a very large investment to build.

The bottom line is that I just don't think it's practical to study this problem using gravity sensing with our current level of technology. Fortunately there are other ways; see the Juno reference I mentioned earlier.

I think you guys are at least a few orders of magnitude off concerning what's possible with radio tracking of Juno. They are using conventional X-band radiometric tracking only, and all they are looking for is the first three even spherical harmonic terms to get information about the core of Jupiter. I find it extremely unlikely that the atmosphere can even be sensed by this.

See
http://trs-new.jpl.nasa.gov/dspace/bitstre...4/1/05-2760.pdf