What is the current best estimate of the mass of Comet 9P/Tempel 1?
The simple answer: We don’t know the mass of comet Tempel 1 at this time. We don’t even know its size very accurately yet. We can estimate its mass by assuming a density and multiplying the density by the volume to compute a mass. M=D x V. Our best estimate is anywhere from 0.1 – 2.5 x 1014 kg. When you think that a kilogram is 2.2 pounds, you can see that Tempel 1 is pretty massive on the scale of something human. On a planetary scale, consider the Earth’s mass, which is about 6.0 x 1024 kg or asteroid Ceres with a mass of 9.445 x 1020 kg. Compared to them, the mass of the comet is almost nothing, well not quite. We should be able to constrain this value better after we analyze images of the impact and have a more accurate shape model of the comet. The goal of the Deep Impact mission is to determine the composition and structure of the interior of the comet. We will arrive at a more accurate value of the mass in the process. A more involved answer: Our current best estimate of the mas
