Emily LakdawallaOct 31, 2007

ESA mission updates: Rosetta and Venus Express

Rosetta is approaching Earth for its second of three flybys, to take place on November 13 at 20:57 UTC. An article on ESA's website details the results of a targeting maneuver, which placed Rosetta on course for the flyby. Rosetta has probably the longest and most circuitous path to its target of any mission I've ever heard of except MESSENGER. Here's the timeline:

LaunchMarch 2, 2004
First Earth gravity assist flybyMarch 5, 2005
Mars gravity assist flybyFebruary 25, 2007
Second Earth flybyNovember 2007
Third Earth flybyNovember 2009
Comet Churyumov-Gerasimenko
endezvous maneuver
May 2014
Landing on the cometNovember 2014
Escorting the cometMay 2014 - December 2015
Nominal mission endDecember 2015

When Rosetta flew by Mars earlier this year, it captured a spectacular image of Mars out the side window from the Philae lander. I don't have any details on the imaging plans for the upcoming Earth flyby, but I do know that there is imaging being planned, and I really hope to see some pictures soon after; I'll post anything I get here as soon as I see it. There is just something about seeing Earth from planetary spacecraft -- especially views with bits of our Earth-built spacecraft intruding in to them -- that is inherently exciting.

As for Venus Express, the latest update on that mission contained some news and also a little humor. Apparently the first science results from the mission are FINALLY going to see the light of day in a special issue of Nature currently scheduled for publication on November 29, 2007 (fortunately not Thanskgiving week here in the US, it's the week after). It's my understanding that this long-delayed publication is one of the main obstacles preventing more Venus Express images and results from being communicated to the public. I fervently hope that more stuff will get released after those articles get in to print. If I am not mistaken, there are actually more Venus images out on the Web from MESSENGER (if you count all the images used in their Venus departure animation) than there are from Venus Express.

Here's the humorous bit. The update also says that "During the NASA Phoenix mission's final approach to Mars, ESA will support NASA by performing Delta-DOR measurements [from its radio tracking stations] in order to get the best positioning data possible." Delta-DOR stands for delta differential one-way ranging, a radio tracking method in which two stations on Earth measure the angle and range to a spacecraft and a fixed radio source such as a quasar; the two radio stations' measurements are compared and the position of the spacecraft determined through parallax. This method produces positional accuracies measured in nanoradians, translating to measurement precisions at Mars' distance from Earth on the order of a kilometer or so. The update continues: "Venus Express was used as a test of the Delta DOR procedures at the end of September and early October, performing three Delta-DOR tests. The results show that we are still at Venus." Ha ha. The important thing here is the interrelationship between NASA and ESA. I think we Americans would like to think that we own deep space and that the other players, ESA, JAXA, and the rest, don't have anything much to offer us; but the fact is that we can reduce our risk and get more science out of our missions through close, friendly, mutually beneficial relationships between us and all the other spacefaring nations.

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