Genesis
A sample of the Sun itself, which survived a crash landing and rewrote the Solar System's oxygen story.
Key facts
- Agency
- NASA (United States)
- Type of mission
- Solar wind sample return
- Target
- The solar wind, at the Sun–Earth L1 point
- Launched
- 8 August 2001
- Samples returned
- Atoms of the solar wind embedded in wafers
- Status
- Completed 2004
The Sun holds more than 99% of the Solar System's mass, so its make-up is the starting recipe for everything else. Genesis set out to bring back a piece of it: atoms carried away from the Sun by the solar wind.
Catching the wind
For more than two years, Genesis sat at the L1 point, about 1.5 million kilometres towards the Sun, outside the shield of Earth's magnetic field. It opened collectors made of ultra-pure wafers of silicon, sapphire, gold, diamond-like carbon and other materials. Particles of the solar wind struck them and buried themselves a fraction of a micrometre deep.
The crash
On 8 September 2004 the capsule returned to Utah, where helicopters were to snatch it in mid-air. Its parachutes never opened, because sensors that should have triggered them had been installed the wrong way round, and it hit the desert at more than 300 kilometres per hour. Many wafers shattered, but the atoms were safely embedded inside the fragments, and painstaking cleaning recovered most of the science.
What it found
In 2011 the team reported that the Sun has a higher share of the light isotope oxygen-16 than Earth, the Moon, Mars and almost all meteorites. Only the calcium-aluminium-rich inclusions in chondrites come close to the Sun's composition. So the rocky planets formed from material that had been changed after the Sun formed. The same reasoning appears in the oxygen three-isotope diagram used to classify meteorites. Genesis also showed that the Sun's nitrogen differs sharply from Earth's.
Key dates
| Date | What happened |
|---|---|
| 8 August 2001 | Genesis launched on a Delta II rocket. |
| December 2001 | Opened its collectors at the L1 point. |
| April 2004 | Closed its collectors after more than two years. |
| 8 September 2004 | The capsule crashed in Utah when its parachutes failed to open. |
| June 2011 | Results on the Sun's oxygen and nitrogen isotopes were published. |
See where this mission fits among all the others in the mission timeline.
Did you know?
Genesis collected only about 0.4 milligrams of solar wind in all, roughly the mass of a few grains of salt.
The Hollywood stunt pilots hired to catch the capsule in mid-air never got the chance.