Extraterrestrial Sample Return
September Genesis, First Since Apollo
|Dramatic non-landing. Helicopter hook will snatch the Genesis spacecraft out of mid-air on September 8, 2004, using a variety of expert pilots and stunt men Credit: NASA|
Since October 2001 NASA’s Genesis spacecraft has exposed specially designed, collector arrays of sapphire, silicon, gold and diamond to the sun’s solar wind. The probe is the first attempt to collect samples of the solar wind and return them to Earth, a terrestrial rendezvous now set for September 2004.
That collection of pristine particles of the sun came to an end last week, when NASA’s Genesis team at the Jet Propulsion Laboratory in Pasadena, Calif., ordered the spacecraft’s collectors deactivated and stowed. The closeout process was completed when Genesis closed and sealed the spacecraft’s sample-return capsule. Genesis was placed into orbit around the first Lagrangian point (L1), a place between Earth and the Sun where the gravity of both bodies is balanced.
"This is a momentous step," said Genesis project manager Don Sweetnam. "We have concluded the solar-wind collection phase of the mission. Now we are focusing on returning to Earth, this September, NASA’s first samples from space since Apollo 17 back in December 1972," he said. Genesis is expected to capture 10-20 micrograms (where 1 microgram is a millionth of a gram) of the solar wind, equivalent to the mass of a few grains of salt.
|Solar wind to be captured is thought to arise from holes in the outer atmosphere or corona, as photographed by the SOHO spacecraft and transmitted by the DSN.|
NASA’s Genesis mission was launched in August 2001 from the Cape Canaveral Air Force Station, Fla. Three months and about one million miles later, the spacecraft began to amass solar wind particles on hexagonal wafer-shaped collectors made of pure silicon, gold, sapphire and diamond.
"The material our collector arrays are made of may sound exotic, but what is really unique about Genesis is what we collected on them," said mission principal investigator Don Burnett. "With Genesis we have almost 27 months far beyond the moon’s orbit collecting atoms from the sun. With data from this mission, we should be able to say what the sun is composed of at a level of precision for planetary science purposes that has never been seen before."
To get Genesis’ precious cargo into the sterilized-gloved hands of Burnett and solar scientists around the world is an exotic endeavor in itself.
Later this month, Genesis will execute the first in a series of trajectory maneuvers that will place the spacecraft on a route toward Earth. On Sept. 8, 2004, the spacecraft will dispatch a sample-return capsule containing its solar booty. The capsule will re-enter Earth’s atmosphere for a planned landing at the U.S. Air Force Utah Test and Training Range at about 9:15 a.m. EDT.
|Earth as seen from Genesis’ current position at L1 point.|
The matter collected is set for return to Earth in a spectacular helicopter capture. As the return capsule parachutes towards the ground, specially trained pilots will catch it in mid-air to prevent the delicate samples from being disturbed by the impact of a landing. To preserve the delicate particles of the sun in their prisons of gold, sapphire and diamond, specially trained helicopter pilots will snag the return capsule from mid-air using giant hooks. The flight crews for the two helicopters assigned for the capture and return of Genesis are former military aviators, Hollywood stunt pilots and an active-duty Air Force test pilot.
When the precious cargo is brought to Earth, scientists will be on their way to better understanding the evolution of our Solar system from its primitive state to the present day. Thought to be the primary source of high-speed streams of charged particles from the Sun, the solar corona is the outermost part of the Sun’s atmosphere. Coronal holes occur where a region is more tenuous than the surrounding corona.