Rosetta spacecraft and asteriod Steins

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by toothdust</i>
<br />Are you making any predictions about this asteroid belt object like you did with the NEAR challenge?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Asteroid satellites are now so common that no one would be surprised if asteroid Stein had one also, even though searches from Earth turned up nothing. But with the flyby of a 10-km asteroid at a distance of 800 km and the canera exposures adjusted for the brightness of the asteroid's surface, seeing a satellite even if one is plainly there would be challenging. We must hope that they take a few longer exposures of the sky around the asteroid, in which case several small moons might show up.

However, as with Eros, Stein is also said to have an "irregular" shape, which might make its gravity field unstable. Then most of whatever is not still in orbit will be found lying on the surface in the form of boulders. But the resolution may be insufficient in such a distant, fast flyby to see many boulders -- unless the camera is very good.

The asteroid itself is different from those previously visited, and is probably from a relatively young family, but definitely not from Vesta (despite claimed associations with Vesta's spectral type). -|Tom|-

The questions below are a little off the topic, but I'll ask? How do you determine the differences of family types for asteriods? Are there many different families of asteroids. How are they different?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />How do you determine the differences of family types for asteriods? Are there many different families of asteroids. How are they different?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Asteroid families are usually recognized by similariry of orbits, all clustered much closer than chance would normally permit. The different types are identified spectroscopically, usually just by examining their largest member. These spectra are then compared with meteorites on Earth to determine the most likely associations.

As I recall, Stein is an enstatite achondrite, a fairly special meteorite type, which is why it was chosen as a target. -|Tom|-

There are several long articles on the wiki about asteroids(Ida&moon as well as others). Do you ever post there-it would be great to see some of the MM stuff at these pages. They say the total mass of all the asteroids(numbering in the millions)is ~4% the mass of our moon- is that enough mass to confirm EPH for example? Lots of new stuff.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />There are several long articles on the wiki about asteroids(Ida&moon as well as others). Do you ever post there-it would be great to see some of the MM stuff at these pages.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Can't happen. Wiki is a broken model in which anyone can post anything and majority rules regatdless of merit. It is loaded with junk.

The new "Knols" model at Google is designed to overcome some of the worst features of Wikipedia. You might find some Meta material there before too long. Whatever is posted can't be vandalized by others.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">They say the total mass of all the asteroids (numbering in the millions) is ~4% the mass of our moon- is that enough mass to confirm EPH for example?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, it is about the expected amount. If Earth blew up today, nothing below about 40 km depth would survive intact because it is under great pressure and would vaporize if that pressure were released suddenly. So Earth would produce about the same mass of asteroids (from its crust and upper mantle only) as exist in the main belt. -|Tom|-

The mass of Earth's crust is about equal to the mass of the moon and the asteroid mass is 4% the mass of the moon. Does that indicate the planet assumed to have produced the asteroids was 4% the mass of Earth 3 times the mass of the moon?