NASA鈥檚 wayfaring Genesis spacecraft has scooped up its last high-energy particle from the Sun, after collecting ions from the solar wind for two and a half years.
The mission is intended to shed light on the formation of the Solar System nearly five billion years ago by revealing the Sun鈥檚 composition. Its quarry will be the first material ever returned to Earth from beyond the Moon when it drops to Earth in September 2004.
On 1 April, the lid was tightened on a canister containing the spacecraft鈥檚 sapphire, silicon, gold, and diamond collector arrays. These are expected to hold 1020 ions, the equivalent of just 0.4 milligrams of protons, electrons, and ions of heavier elements such as helium and oxygen.
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鈥淚t鈥檚 effectively like dipping your spoon into the Sun and being able to analyse that, almost like you would a sample of seawater,鈥� says Christopher Owen, a plasma physicist at Mullard Space Science Laboratory in Surrey, UK, who is not involved in the mission.
Pristine sample
One key to the mission鈥檚 success is its distance from Earth, says Owen. Genesis collected its solar wind samples from a distance of several hundred times the Earth鈥檚 radius toward the Sun. That is well beyond the magnetosphere, the shield formed by the Earth鈥檚 own magnetic fields that deflects solar wind particles and extends 10 to 15 times the Earth鈥檚 radius.
鈥淚f you try to collect from inside this magnetic shield, you get contamination from Earth鈥檚 upper atmosphere,鈥� Owen told 快猫短视频. 鈥淵ou have to get out beyond the magnetosphere to get a pristine sample.鈥�
Later in April, the spacecraft will begin a series of trajectory changes to begin its 1.5 million kilometre trip back toward Earth. It will fly by the planet on 2 May, looping around in space in order to drop its science sample above the US state of Utah on 8 September.
In a dramatic mid-air capture manoeuvre, a team of Hollywood stunt pilots and military aviators will then attempt to snag the canister鈥檚 parachute using hooks from two helicopters. That will be the moment mission managers have been waiting for.
鈥淟ike all sample return missions, Genesis science really begins when the spacecraft phase of the mission ends,鈥� says Donald Burnett, the mission鈥檚 principal investigator and a geochemist at the California Institute of Technology. 鈥淚t鈥檚 been a long time coming, but we can鈥檛 wait to get to the analysis phase.鈥�