Contemplating the Cracked Capsule
|Carefully dissecting the pod. The Genesis sample return capsule landed well within the projected ellipse path in the Utah Test & Training Range on Sept. 8, but its parachutes did not open. It impacted the ground at nearly 200 mph.
Scientists still hope to recover science results from the Genesis space capsule, which crashed to the ground on Wednesday when its parachutes failed to deploy.
"The capsule was designed to sustain 75 Gs. The amount of deceleration it saw on impact… I think the technical term is ‘gobs’," says Don Sevilla, Genesis payload recovery lead. He estimates the capsule probably sustained a bit more than the 75-G design limit.
The shattered capsule has been moved to a clean room at the Michael Army Air Field, located at the U.S. Army Dugway Proving Ground in Utah. It is unknown at this time when the capsule samples can be moved to the Johnson Space Center in Houston, Texas.
The biggest problem right now is contamination. Dirt entered the capsule on impact, and scientists foresee a long clean up ahead of them.
"The sample return capsule has been broken up pretty badly, and there’s a fair amount of dirt," says Sevilla. "But the very contamination-sensitive materials inside the [sample] canister, we’re not talking about great clods of dirt. There’s still polished metal, looking very pretty inside our rather ugly patient."
|Wafer fragments post-recovery. "I want to emphasize the excellent work by the navigation team to bring the capsule back exactly on target was key in our ability to recover the science," said Andrew Dantzler, Director of the Solar System Division at NASA Headquarters, Washington. "In addition, the robustness of the design of the spacecraft was the reason it could take such a hard landing and still give us a chance to recover the samples," he said.
Sevilla says they only have explored the inside of the sample canister using a flashlight and a mirror on a stick.
"We weren’t prepared for having all the right tools for the operation we have," he notes. "We are going to be doing some sawing and snipping [once we get the proper tools]. I think we’re going to start peeling the layers of this onion tomorrow and Monday."
The thin collector wafers inside the Genesis capsule broke on impact, although some of the pieces are quite large. These wafers were used to gather atoms streaming off the sun’s corona.
"We’re being very meticulous in the way we open this canister up, partially because we have to pick up all the pieces of these silicon wafers of the fragile collectors that are strewn about the canister structure," says Sevilla.
The wafers are made of different materials, and the five individual wafer arrays each have a different thickness, so that should help scientists puzzle out which pieces fit together.
The solar wind samples are not deeply embedded in the wafers, but reside within a shallow surface area about 50 nanometers deep. Scientists will have a delicate task ahead of them as they try to clean the wafers without affecting the samples. Even ultra-pure water could corrode the surfaces.
The capsule also holds four segments that acted as a kind of magnifying glass, concentrating a large amount of solar wind into a small sample. At least two of these concentrator segments are intact. The concentrator segments were used to measure the isotopic oxygen composition of the sun. This information could be used to determine the role oxygen played in the formation of the solar system.
Gold foil contained on the canister’s lid was designed to collect nitrogen isotopes in the solar wind. Analyzing the sun’s nitrogen could help determine how the atmospheres of the planets in our solar system evolved. The foil seems to be in good condition, although Don Burnett, Genesis Principle Investigator, says it has been seriously contaminated by soil and may be very difficult to clean.
The Genesis science team had planned to run at least 18 different experiments on the solar wind samples. At this point, it is uncertain how many of these experiments can still be conducted. . Burnett says measuring the carbon isotopes in the samples may present the biggest challenge, since the greatest sources of contamination on Earth are carbonaceous materials in the soil and atmosphere.
|"This may result in snatching victory from the jaws of defeat," added Dr. Roger Wiens of the Los Alamos National Laboratory, a member of the Genesis science team. "We are very encouraged."
The collector materials won’t be touched until an appropriate method to clean them is settled upon. Sevilla says they will implant comparable test materials with ions, get them dirty, and then see which cleaning method works best. Burnett says they also may appeal to the semiconductor industry for help.
The Genesis sample return capsule impacted the ground at 193 miles per hour. The pyrotechnic devices that were designed to release the parachutes did not fire, but scientists believe this was not due to a flaw in the parachute system. Instead, the electronic commands that would have triggered the pyros were never sent.
"It points to a command and control problem, not a problem of the parachute or pyro device," says Sevilla. Scientists can only speculate at this point exactly where the system failure occurred.
That will be the job of a mishap review board, and two are already being organized – one by NASA Headquarters and one by the Jet Propulsion Laboratory. NASA Headquarters already has appointed Michael Ryschkewitsch from the Goddard Space Flight Center to lead their board. The investigation report from that board is due in mid-November.