OSIRIS-REx
OSIRIS-REx
One-line summary: NASA's asteroid sample-return mission to Bennu, which brought back material containing all the nucleobases of DNA and RNA — evidence that life's building blocks fall from space.
What it is
A car-sized nasa spacecraft (Origins, Spectral Interpretation, Resource Identification, Security–Regolith Explorer) that traveled to the near-Earth asteroid Bennu (~half a kilometer across), collected a sample, and returned it to Earth (parachute drop into the Utah test range).
Why it matters to science
Its returned sample is the source's strongest piece of evidence for cosmic origins of biology: it contained not just amino acids but all the nucleobases of DNA and RNA — plus nucleobases life doesn't even use. This is the empirical anchor for stellar-nucleosynthesis-to-life-building-blocks and the idea of panspermia.
Key facts
- Target: asteroid Bennu, ~0.5 km across; crosses Earth's orbit (may hit Venus before Earth; no known Earth-impact certainty).
- Bennu's minerals show it was once soaked in water — asteroids delivered both water and organics to early Earth.
- The sampling head was a "vacuum cleaner"; the surface was unexpectedly covered in boulders, so the craft had to be made autonomous after launch (a one-way command takes ~15 minutes — too far to joystick) to find dust-filled micro-craters and abort if unsafe.
- Returned sample contained all DNA/RNA nucleobases, plus unused ones — "the letters of our genetic code were in that asteroid" (michelle-thaller).
Open questions
- If asteroids carry unused nucleobases, would life elsewhere use a different genetic alphabet? (see stellar-nucleosynthesis-to-life-building-blocks)