Asteroid 2867 Steins. A block knocked off giant asteroid 4 Vesta?

3488 · Jul 5, 2008

Mithridates has got me thinking, which is of course a good thing.On Friday 5th September 2008, the ESA Rosetta Spacecraft passes only 800 KM from the 2 KM - 5 KM wide main belt asteroid 2867 Steins. Preliminary spectral analysis seems to suggest a basaltic makeup & that 2867 Steins is actually a very rare type of asteroid & the first such type to be scrutinized by a spacecraft.I wonder, could 2867 Steins be a piece blasted from 4 Vesta, the first primary objective for the DAWN spacecraft, & could the images & other data from Rosetta, be used to assist the DAWN team in planning the 4 Vesta part of the mission, before heading off to 1 Ceres?Andrew Brown.  <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

mithridates · Jul 6, 2008

While we're at it, I'll repost my question I included in the response to your response here since some others might have some good sources on this: "That reminds me, I don't suppose you know of a good source that shows how much help these flybys are in improving the accuracy of our observations from Earth? 2867 Steins is supposed to be around 2-5 km, and I assume after we have all the information from the flyby it'll be fed back into observations we have from here to make our estimations that much more accurate, but I have no idea by how much, and when we'll reach a point where we can make some really accurate guesses from Earth. I'm also curious about what the Vesta encounter will do for our observations of Ceres, once we've had a closeup look of an asteroid that massive. Basically I'm curious about whether we'll be able to get some better observations/estimates of Ceres before Dawn actually arrives, because 2015 still is a really long ways away and I hate waiting." After writing that I was also thinking today about whether it would be worth it to send up a mission just to continually fly by as many asteroids as possible during a period of some ten to twenty years, both big and small, to gather as much information as possible to help us extrapolate with more accuracy from the observations we have on Earth. What would be the maximum number of asteroids that could be flown by in a period of a decade or so? This wouldn't include any orbit insertions, just as many encounters as possible. <div class="Discussion_UserSignature"> ----- http://mithridates.blogspot.com </div>

MeteorWayne · Jul 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>While we're at it, I'll repost my question I included in the response to your response here since some others might have some good sources on this: "That reminds me, I don't suppose you know of a good source that shows how much help these flybys are in improving the accuracy of our observations from Earth? 2867 Steins is supposed to be around 2-5 km, and I assume after we have all the information from the flyby it'll be fed back into observations we have from here to make our estimations that much more accurate, but I have no idea by how much, and when we'll reach a point where we can make some really accurate guesses from Earth. I'm also curious about what the Vesta encounter will do for our observations of Ceres, once we've had a closeup look of an asteroid that massive. Basically I'm curious about whether we'll be able to get some better observations/estimates of Ceres before Dawn actually arrives, because 2015 still is a really long ways away and I hate waiting." After writing that I was also thinking today about whether it would be worth it to send up a mission just to continually fly by as many asteroids as possible during a period of some ten to twenty years, both big and small, to gather as much information as possible to help us extrapolate with more accuracy from the observations we have on Earth. What would be the maximum number of asteroids that could be flown by in a period of a decade or so? This wouldn't include any orbit insertions, just as many encounters as possible. Posted by mithridates</DIV>Hmmm, well observations of any one asteroid have limted value for other asteroids.For 99.999% all they are is a 1 pixel wide point of light. Size estimates are then based on the brightness, distance, and a range of albedos (the amount of sunlight reflected) which varies quite a bit from one asteroid to another.So  an asteroid of magnitude 23.1 at 1 AU distance ("H" is the magnitude at 1AU standard distance in lists of asteroids) can be between 63 and 140 meters in diameter, depending on the albedo. If it's a shiny meteor, it's 63 meters, if it's a dark asteroid, 140 meters. How reflective it actually is is an unknown unless it's bright enough to get a spectrum, in which case you can make some guesses as to the reflectivity.Ceres, being quite large is pretty well known  (it is a Dwarf Planet after all), enough that we know it is round and at least partially ice covered, so I doubt the investigation of Vesta will tell  us much more.As far as a dedicated flyby mission, you might be able to sample a dozen or in a decade long mission, but considering finances, that just ain't gonna happen.Despite the popular images of the asteroid belt, they are actually very far apart. MW <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

mithridates · Jul 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Hmmm, well observations of any one asteroid have limted value for other asteroids.For 99.999% all they are is a 1 pixel wide point of light. Size estimates are then based on the brightness, distance, and a range of albedos (the amount of sunlight reflected) which varies quite a bit from one asteroid to another.So  an asteroid of magnitude 23.1 at 1 AU distance ("H" is the magnitude at 1AU standard distance in lists of asteroids) can be between 63 and 140 meters in diameter, depending on the albedo. If it's a shiny meteor, it's 63 meters, if it's a dark asteroid, 140 meters. How reflective it actually is is an unknown unless it's bright enough to get a spectrum, in which case you can make some guesses as to the reflectivity.Ceres, being quite large is pretty well known  (it is a Dwarf Planet after all), enough that we know it is round and at least partially ice covered, so I doubt the investigation of Vesta will tell  us much more.As far as a dedicated flyby mission, you might be able to sample a dozen or in a decade long mission, but considering finances, that just ain't gonna happen.Despite the popular images of the asteroid belt, they are actually very far apart. MW Posted by MeteorWayne</DIV>Actually a possible dozen in a decade is more than I had thought would be doable, so if that's correct it turns out they're closer than I had thought. <div class="Discussion_UserSignature"> ----- http://mithridates.blogspot.com </div>

3488 · Jul 28, 2008

Hi all,Asteroid 2867 Steins encounter by the ESA Rosetta spacecraft countdown. Andrew Brown.  <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

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