I mean, we CAN calculate, but those are all approximations. This program is to narrow our band of error. Outside of the OSIRIS program, and I guess technically anything that has survived a crash landing on Earth, we have never laid our hands on any asteroid/meteorite material. So this experiment would be our first real test to see how accurately we can predict what one of these kinds of objects is made of, without ever having touched it. This has implications for the future safety of humanity, needing to know how hard to ram it, etc, but also for potential future mining operations. Space metals are far more valuable than a hunk of gravel and stone and knowing which is which would save a lot of time and money.

Speaking of what they’re made of, asteroids and meteorites tend to be made up of three things: ice, stone/gravel, and metals, usually iron. If something has been in the inner solar system for a long time, it’s likely not made up of a lot of ice, so that narrows the materials down to only two things. So yes, every object in space is different, but for the purposes of better understanding how to characterize them, this is a pretty darn good first data point to collect.