SAMPLE
HAYABUSA AND OSIRIS-REX
Three spacecraft went to fetch pieces of asteroids.
BEGIN — CHAPTER 01 →Ground truth that no telescope can give
Asteroids are the building blocks that never became planets.
A sample collected on purpose has a known address.
Everything that could fail did, and it still came home
Hayabusa launched on 9 May 2003.
The capsule landed in Woomera on 13 June 2010.
Why ion engines?
Tsiolkovsky's rocket equation.
Where a pebble can be thrown into orbit
Itokawa is a rubble pile.
On such a body gravity is tiny.
Uniform-gravity, non-rotating estimate.
Making a crater, then landing beside it
Hayabusa2 reached Ryugu on 27 June 2018.
On 5 April 2019 the impactor made a crater.
The capsule landed on 6 December 2020.
Hayabusa2 flies on to 1998 KY26.
Touch-and-go into a ball pit
OSIRIS-REx arrived at Bennu on 3 December 2018.
On 20 October 2020 it touched down.
44,500 km/h into the top of the atmosphere
The capsule hit the atmosphere at 44,500 km/h.
Kinetic energy grows with the square of speed; heating with the cube.
Heating ratios ignore radiative heating.
Grams of the early Solar System
121.6 g came back from Bennu.
Bennu's sample holds amino acids and nucleobases.
Lunar samples for scale.
From a few grains to a cupful
From a few thousand specks to more than a hundred grams.