Emily LakdawallaNov 10, 2008

What's up in the solar system for the week of November 10

With the whirlwind of events taking place across the solar system throughout October, I couldn't find the time to keep up with my erstwhile weekly updates of events across the solar system. Things have quieted down again, so I can take a breath, step back, and scan across the planets, moons, and assorted other stuff to see what's going on. We'll start in the inner solar system and journey outward.

Having completed its second flyby of Mercury, MESSENGER is back in its interplanetary cruise mode. Venus Express is still in orbit at Venus; there's no news on that mission. On my calendar I have a note that the extended mission ends on January 22. Does anybody reading this have any information on any plans to extend the mission again?

As of last week there are now three spacecraft active at the Moon: China's Chang'e 1, Japan's Kaguya, and India's Chandrayaan-1. The International Lunar Decade truly is in full swing. I have no updates on the status of either Chang'e 1 or Kaguya, except that Kaguya's mission has been extended, as expected (I'll write more about that when I get a chance). An update on the ISRO website states that Chandrayaan-1 has successfully performed the first in a series of maneuvers designed to lower it into its circular science orbit. Allegedly, last week it used its camera to photograph the Moon, but those images have not yet been officially released to the Internet. I've only seen grainy images that looked as though they were grabbed from a television broadcast. An article in The Hindu (a publication that is producing pretty much daily updates on Chandrayaan-1) further states that the Moon Impact Probe will be shoved off from the spacecraft on November 14 or 15.

Moving along to Mars, the top story there is the end of the Phoenix mission. I'll post more about this today or tomorrow, and you can also look forward to a formal news article by A. J. S. Rayl. My last update on the mission status was, it turns out, written after the last contact was made between Earth and the spacecraft.

The rest of the Mars spacecraft are operating fine, doing some last science before Mars goes into solar conjunction from November 18-24. Conjunction is when Mars appears to be in the same position in Earth's sky as the Sun. It has no direct effect on the health of spacecraft, but radio noise from the Sun makes it very difficult for radio transmissions to reach Earth without corruption of the data, so science activities are curtailed. I'm sure we'll still be in communication with all the Mars spacecraft throughout conjunction; radio scientists typically use the opportunity of conjunction to use the spacecrafts' radio signals to probe the structure of the solar corona.Mars Reconnaissance Orbiter and 2001 Mars Odyssey have been kept very busy in the last week in attempts to communicate with Phoenix. I don't know how much that might affect their science operations; it should only affect them near the north pole, clearly. Both have kept up their regular delivery of images to their respective websites (HiRISE and THEMIS).

Mars Reconnaissance Orbiter has several other active instruments, of course. A couple of weeks ago the CRISM team announced that they'd discovered hydrated silica -- otherwise known as opal -- on Mars, near and within Valles Marineris. This is a mineral that, on Earth, is almost exclusively associated with hydrothermal systems (that is, places where there is underground liquid water that is heated by some process or another, usually nearby volcanic activity; CRISM found it on Mars in rocks that are relatively young. MARCI is still following Mars' weather, monitoring the onset of dust storm season. As valuable as their input has been to the Phoenix mission, they were evidently unable to predict the sudden dust storm that doomed Phoenix. (I mean no criticism of the MARCI team. We can't predict sudden storms very well on Earth, much less on Mars.) Mars Express hasn't released any new data lately. The "Mars Webcam" site hasn't been updated for a month -- the responsible staffer was on holiday (ESA's web staff is very, very small in number) -- but hopefully some new images will show up again soon. Once Mars goes into conjunction, there'll be no new "Mars Webcam" images until March, when they'll once again show us Mars in a crescent phase. During much of this time, the HRSC cameras will enjoy optimal conditions for photographing the surface, so the spacecraft's resources will be directed toward high-quality stereo color imaging.

Dropping onto the Martian equator to visit the rovers, we find that dust is affecting Spirit, too. It's now suffering low power levels as a result of its first real dust storm of the season. Opportunity, on the other hand, is continuing to stride across the plains, driving (in the last week) close to 100 meters every other sol. It's now late winter in Mars' southern hemisphere (Ls 156°).Cassini is now past periapsis (Saturn closest approach) of rev (orbit) 92. It completed its "T46" flyby of titan last Monday (that was the 47th targeted Titan flyby of the mission), a flyby focused on radio science. Radio signals were broadcast from Cassini through Titan's atmosphere to Earth; the way they were attenuated by the passage through the atmosphere will tell scientists about the structure of that atmosphere. Cassini will reach apoapsis, beginning rev 93, on Wednesday; its orbits are still highly inclined at more than 70 degrees, but they are getting a little longer, eight days now instead of the very convenient (for timekeeping purposes) seven-day orbit it employed through the late summer. My Cassini tour page says there's a Voyager-class flyby of Tethys on Sunday, but I don't know if there are plans to take pictures. Most of the recent raw pictures have been devoted to Saturn's rings, now lit by glancing light as Saturn gets ever close to its equinox.

Moving on out into spacecraft in deep space or otherwise cruising to their destinations...Dawn is cruising along, headed toward a Mars flyby in mid-February (that's only three months away, folks!), which will speed it on toward its planned 2011 arrival at Vesta. Deep Impact is done with its extrasolar planet observations and is cruising toward its 2010 flyby of comet 103P/Hartley 2. If I understand the weird Google translations of these updates on Hayabusa correctly, the spacecraft is near perihelion. The International Cometary Explorer is slowly being brought back to life, on course for a return visit to Earth in 2014.New Horizons is 12.3 AU from Earth and 20.0 AU from Pluto. A recent update on their Twitter page states that tracking has shown they're about 47,000 kilometers off their Pluto encounter target point, so they'll correct that with "a small rocket burn in 2009 or 2010: just 0.085 mi/hr (22 cm/s) will fix it." There's been nothing new from Rosetta since the Steins flyby. The Voyager 1 and 2 website has lately been updated with a pile of weekly status reports (which, for reasons I don't understand, seem to get posted online somewhat less frequently than quarterly). The most recent one, dated September 12, says that things are going fine with both spacecraft. It now takes an amazing 29 hours and 49 minutes for signals to traverse the distance from Earth to Voyager 1 and back. Last but not least, Ulysses appears to still be alive.

Sorry for the lack of pictures in this update -- I ran out of time! It was either post today with no pictures, or post tomorrow with them, so I elected to post today.

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