3 ms·
It's already passed pedigree with the sun. It is traveling slowly enough that if it's a discarded stage the spaceship should already be here.
by valuearb 9y ago
It's already passed pedigree with the sun. It is traveling slowly enough that if it's a discarded stage the spaceship should already be here.
- semi-extrinsic 9y agoHow do you know that, without knowing the non-booster-assisted deceleration rate of the spaceship? (Presumably the hypothetical ship separated from the booster when that was out of fuel, and then the ship continued decelerating on its own to get to a velocity congruent with a stable orbit in our system).
- valuearb 9y agoThe object is traveling at 26Km/sec, earth is orbiting at 30 Km/sec. To generate a "stable orbit" is a matter of maneuvering at that velocity. So it's really unlikely that the parent ship is traveling much slower than the discarded booster, and so it's arrival is unlikely to be much later.
- xelxebar 9y agoI'm assuming autocorrect helpfully fixed "perigee" to "pedigree" for you. It's a nice little malapropism though. Anyway, minor point but "perigee" usually means closest approach to Earth; "-gee" is from the Greek for Earth (as is "geo-"). In the case of the sun, we have the word "perihelion", and for generic orbits around an object, you generally hear "periapsis". And just for completeness, I'll mention that the counterpoint to periapsis is apoapsis, with apogee and aphelion being the obvious specializations. There are more words in this pattern for various different objects; Wikipædia has all the gory details: https://en.m.wikipedia.org/wiki/Apsis https://en.m.wikipedia.org/wiki/Apsis
- valuearb 9y agoAutocorrect figured out I meant that we need to make sure aliens have sufficient pedigree before we deign to talk to them.