Who discovered 2 Pallas and when?
2 Pallas was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on the 28th of March 1802. Olbers found it while searching for Ceres; Pallas happened to be passing near Ceres at the time.
Questions about 2 Pallas
Short answers, pulled from the story.
How large is 2 Pallas compared to other asteroids?
2 Pallas is the third-largest asteroid in the Solar System by volume and mass. Its estimated volume is equivalent to a sphere roughly 507 to 515 km in diameter, making it 90-95% the volume of Vesta. It is 79% the mass of Vesta and 22% the mass of Ceres.
What is the orbital inclination of 2 Pallas and why does it matter?
2 Pallas has an orbital inclination of 34.8 degrees, which is unusually steep for a large asteroid. This makes it relatively inaccessible to spacecraft and causes objects to impact Pallas at roughly twice the average velocity of impacts on Vesta or Ceres, producing an exceptionally cratered surface.
What is the Pallas family of asteroids?
The Pallas family is a group of asteroids with orbital parameters similar to 2 Pallas, first identified by the Japanese astronomer Kiyotsugu Hirayama in 1917. Since 1994 more than ten members have been confirmed, with semi-major axes between 2.50 and 2.82 AU and inclinations of 33-38 degrees. Their family membership was confirmed by spectroscopic comparison in 2002.
Has any spacecraft visited 2 Pallas?
No spacecraft has visited 2 Pallas. A flyby during the Dawn mission was ruled out because of Pallas's high orbital inclination. The proposed Athena SmallSat mission, which would have conducted a flyby in 2022, was not funded.
What is the surface of 2 Pallas made of?
Pallas's surface is composed primarily of silicate material low in iron and water. Its spectrum closely matches the Renazzo carbonaceous chondrite meteorites, a particularly primitive type. As of 2020, researchers had identified 36 craters on its surface, 34 of them larger than 40 km in diameter.