Flying the Sun to Safety
|Flying Genesis to safety will be eased by practice runs like the helicopter capture shown. Credit: NASA|
When the Genesis capsule comes back to Earth with its samples of the Sun, helicopter pilots will be waiting for it, ready to snag it out of the sky.
This dramatic mid-air rescue will prevent the collector materials from being broken or damaged, which could happen if the capsule parachute-landed to the ground.
Civilian pilots Dan Rudert and Cliff Fleming are prepared for the challenge, having practiced their maneuvers many times over the Air Force’s Utah Test and Training Range.
“It’s very exciting. Cliff and I are going to be participating in aviation history. This will be the first time a mid-air retrieval [captures something] that came in from outside the Earth’s orbit,” says Rudert.
|Genesis collects solar wind at the first libration point, L1.|
The capsule will enter Earth’s atmosphere above Oregon at 9:55 am Mountain time on September 8. It will speed in at 24,600 miles per hour – so fast it will travel to Utah in just 96 seconds. The friction of the atmosphere will slow the capsule down to Mach 2. At an altitude of 108,000 feet, a drogue shoot will deploy and slow the capsule down to subsonic velocities. The main parachute, a parafoil, will deploy six minutes later, at an altitude of 20,000 feet.
Two helicopters will be waiting at 10,000 feet, seven miles away from the predicted intercept point. Each helicopter will have three crew members: a pilot, a director of flight operations, and a payload master. Although the crew could potentially spot the capsule as high up as 16,000 feet, they won’t try to grab the capsule until it descends to 8,500 feet above sea level (which in the Utah desert is about 4,200 feet above the surface).
Ground controllers at Hill Range Radar will be scanning the skies for the capsule, and once they locate it they will send a position advisory to the helicopters. All six crew members then will try to spot the capsule as it falls out of the sky.
“Depending on visibility, we can see it anywhere from two to five miles out,” says Roy Haggard, director of flight operations for the lead helicopter. “It’s an interesting time for the crews to be straining, looking into space to find our parafoil.”
|Helicopter pilot, Dan Rudert.|
The lead helicopter will use a long line that has a hook at the end to grab onto the parafoil, while the second helicopter waits 1,000 feet behind the lead. If the lead helicopter misses, the second helicopter will swoop in and attempt a capture. The pilots will be able to make these capture attempts until the capsule descends to an altitude of 500 feet. They estimate this will give them five capture opportunities.
Once the parafoil is captured, the helicopter will slowly lower it down and place it down to Earth. The other helicopter will land and its crew will detach the parafoil, and then the capsule will be flown to the Michael Army Air Field at the U.S. Army Dugway Proving Ground, where a temporary clean room is set up. Less than a week later, the samples will be moved to a special laboratory at NASA’s Johnson Space Center in Houston.
“The difficulty, out of a scale 10, is probably somewhere between an 8 or 9, because it’s a two-fold process,” says lead helicopter pilot Rudert. “First, we have to be lined up directly where the hook can capture it – to be the right height above that. One of the difficulties is that we’re so high up there are no visual cues – no trees or houses – to give you your distance or space in time.”
|As seen from the pilot’s seat, the moment of capture, when the helicopter lowers its fishing pole hook and snags the Genesis parachute.|
“The second process is when it turns into a 100-foot suspended load below the helicopter. A five-foot disk, at 100 feet, looking straight down off the helicopter, looks like the size of a Frisbee. Of course it would be defeating the point if we brought it down and hit it hard to the surface or dragged it along the ground. So it’s up to us to bring it down very carefully and gently to the surface.”
If the helicopters miss and the capsule parachutes to the ground, the damage could be extensive. By the time it lands, the capsule will only be traveling forward at about 20 miles per hour. Haggard says if it lands on a perfectly smooth sandy spot, there might be no damage. “But if it landed up against the base of one of the many mountains that’s out there, and ran into something hard downwind, it could hit with tremendous impact and really wreak havoc with all the samples.”
Don Burnett, Genesis principal investigator, says that a calibrated instrument on the capsule could be damaged, and the solar collector arrays could break into fragments, which then would abrade the rest of the collector.
Burnett says the capture is on a stopwatch, because the scientists want to apply nitrogen to the canister as fast as they can to purge it of any contaminated air that might be inside. Once the capsule is sent to the temporary clean room, the back bolts holding the shield of the capsule will be sawed off in order to connect the line of pure nitrogen.
“After that, there’s no hurry; we can take our time,” says Burnett. “We will slowly pack up the components of the capsule. We will take the canister, which contains all the materials, out, and put it in its own special shipping container.”
|Semiconductor-grade panels used to collect solar wind in quantities equivalent to a few grains of sand.|
But if the capsule parachutes to the ground, the scientists won’t be able to follow their timetable.
Haggard is confident, however, that the helicopters will be able to make the capture. He says that more than 25,000 mid-air retrievals have been successfully achieved using fixed wing aircraft, and about 25,000 have been done with helicopters.
“Their success rate – if they can find the object – is in the very high 90 percentile range,” says Haggard.
NASA is using civilian instead of military pilots because of the special skills these pilots have. Their work on Hollywood movies has required them to fly very closely and precisely toward moving objects, such as cars, motorcycles, and jet skies, so the camera could film them. These particular “stunt pilots” also have flown with an external load line for other jobs, such as moving objects like swimming pools, or placing air conditioners onto rooftops. Rudert also has used external load lines while working with firefighters in the US Forest Service.
“I had the pleasure of trying to track down the two best pilots in the world that would be willing to do this mission,” says Haggard. “I’ve talked to many good helicopter pilots, and most are acrophobic. They don’t like being up high in the air – they spend their entire lives between the ground and maybe 500 feet, seldom over 1,000 feet. We say, ‘Well, we want you to loiter at 10,000 feet, ” and they say, ‘No I don’t want to do that.’”
“Then we say, ‘Oh, and we want you to do an intentional mid-air collision with another aircraft. And you’re going to capture it and then set it down on the ground.’ They say, ‘No, I don’t want to do that – that sounds like a stunt!’ In every avenue we explored, we were always referred back to stunt pilots. Among the six flight crew members, five hold Screen Actor’s Guild cards as stunt men. We know that the best civilian pilots do fly stunts for Hollywood because it is the most exciting, entertaining, and challenging work they can find.”