ESA Rosetta, news, updates and discussion |
ESA Rosetta, news, updates and discussion |
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#1
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![]() Member ![]() ![]() ![]() Group: Members Posts: 562 Joined: 29-March 05 Member No.: 221 ![]() |
Well Rosetta isn't going to get to 67P/Churyumov-Gerasimenko (Chury) till 2014, but it's not to early to set up a thread. There are a bunch of earth fly-bys, a Mars encounter at 200km in 2007 and a few asteriod passes. Not to mention the mission to land on the comet itself.
Only another nine and a half years to go. |
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#2
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 ![]() |
a 3000 km flyby is pretty useless for any asteroid mass determination unless the 'oid is something really big, like over 100 km. What's Lutetia's est. diam?
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#3
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Member ![]() ![]() ![]() Group: Members Posts: 599 Joined: 26-August 05 Member No.: 476 ![]() |
Around 100 km.
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#4
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 ![]() |
Well, Galileo flybys of Gaspra and Ida were around the same ballpark distance (1600 and 2400 km, respectively) and mass estimates were acquired, probably through two-way doppler before and after the encounter. Rosetta is reaction wheel controlled so in principle it should allow a rough mass estimate to be given in the same way, especially since Lutetia is significantly more massive than the former two so its signature should be much more easily detectable.
EDIT: On second thought, determining Ida's mass was much more straightforward. It has a moon orbiting at a known distance and a known orbital period so mass can be determined to high accuracy. As for Gaspra, the following page has this to say: QUOTE Most asteroids are too small to produce noticeable effects on spacecraft. Galileo's 1991 encounter with the asteroid Gaspra produced only images. In 1993, however, Galileo is scheduled to fly by the asteroid Ida, and it is expected that the relatively close approach to Ida will yield the first experimentally measured estimate of an asteroid's mass and therefore density. The corresponding constraints on its composition will allow new insight into theories of the evolution of the solar system and asteroid belt.
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