Solar-Wind Gems Take the Plunge

The return mission of the Genesis solar wind project ended up in a heaping pile in the Utah desert on Sept. 8. The Genesis capsule was launched three years and one month earlier on Aug. 8, 2001. Its mission: to capture samples of solar wind particles on passive collectors made from ultra-pure wafers of float-zone silicon, Czochralski-grown silicon, single-crystal synthetic sapphire, epitaxial-silicon on sapphire, gold on sapphire, diamond-like carbon on silicon, a carbon-cobalt-gold on sapphire, and something called Vitraloy (a true metal glass).

NASA notes that the return capsule “entered Earth’s atmosphere at 9:52 a.m. and entered the preplanned entry ellipse in the Utah Test and Training Range as predicted.” But the parachute did not deploy, and the capsule hit the ground at 193 miles per hour.

Itisrocket science! The solar wind is a flow of various types of ions that stream outward from the sun. The objective of the Genesis experiment was to capture those ions, bring them back, and then chemically and isotopically analyze them to help scientists understand the origins of all objects in the solar system.

The very high purity gems were chosen because they are capable of collecting tiny amounts, only a few parts per million, of impurities, which can then be analyzed when returned to earth. The gems also had to be able to survive extremes in temperature, repeated thermal cycling, the vibrations of launch, and, as NASA describes it, “the shock of landing without cracking or flaking”—especially when the parachute doesn’t open.

Another requirement is that when the ions of the solar wind become embedded in the collector plates, they must not diffuse out. NASA chose different types of materials to ensure that the different types of solar ions would stay in at least one collector and could then be extracted by a process such as heating or laser ablation—the same processes the jewelry industry uses to identify beryllium-treated sapphire.

After a two-year exposure time, the instruments were folded up, sealed into a canister, and returned to earth for laboratory analysis. Unfortunately, the crash landing breached both the outer shell and the science canister inside.

Total cost of the mission was estimated at $260 million. Only time will tell whether the ions of the solar winds survived the crash.

For more technical information about the mission, log onto www.gps.caltech.edu/genesis or www.nasa.gov/genesis.