How to Bring a Comet Home
On January 15, 2006, after more than 7 years and billions of miles of travel through space, the Stardust spacecraft finally returned to Earth with some precious cargo -- pristine samples of comet and interstellar dust. Stardust will provide the world's first opportunity to analyze preserved samples of the fundamental building blocks of our Solar System that formed 4.6 billion years ago.
During a brief but daring encounter with Comet Wild 2 on January 2, 2004, Stardust captured thousands of particles and began its arduous two-year journey back to Earth, where its Sample Return Capsule (SRC) will land in the Utah Test and Training Range (UTTR) within the Great Salt Lake Desert.
The SRC reentered Earth's atmosphere and parachute toward the surface, touching down at approximately 3:15 AM on January 15, 2006. Upon its long anticipated landing, the SRC separated from the parachute, which floated on its own to the ground several yards away from the landing site.
After the capsule's touch down, three helicopters began their complex task of retrieving Stardust's precious cargo. They flew approximately 10 miles across the desert lakebed toward a UHF homing beacon emitted from the capsule. The first helicopter, flown by a commercial pilot, led the way; the second helicopter, a Blackhawk, was flown by an Army Reserve pilot; and lastly, the third, flown by another commercial pilot, brought up the rear of the helicopter fleet.
Accompanying the lead pilot was UTTR's On-Scene Commander (OSCAR), as well as a safety specialist from Lockheed Martin, the aerospace corporation responsible for building the Stardust spacecraft. And in order to ensure the most efficient and safe retrieval of the capsule, the second helicopter carried the recovery Operations Manager (RCO), a Science Co-Investigator (Co-I) and a curation representative and recovery specialist from Johnson Space Center (JSC).
Staggering their arrival to the landing site, the first helicopter's navigation unveiled the exact location of the capsule and began sweeping the SRC landing site with a spotlight to catch its reflection on the dark desert floor.
Once the helicopters set down, the team then began the process of preparing the SRC for its history-making analysis. First, a gas sample was taken and stored for preliminary examination. Then, the SRC was placed inside a handling fixture and double bagged to ensure that no Earthly materials touched the capsule and contaminate its contents. Then, the capsule was flown to a prepared staging area cleanroom in a nearby hangar.
Just before entering the cleanroom, Lockheed Martin engineers, clad in "bunny suits" removed the SRC from its double bags, and took two more gas samples from within the unopened capsule for further examination. Then, because the capsule was encased in thick SLA-561 ablator materials that protected it from the heat of reentry into Earth's atmosphere, the team had to drill into these protective coatings to access and remove the 12 bolts from the backshell of the capsule.
This is the first time that the SRC was opened after its ambitious encounter with Comet Wild 2 in 2004.
Deep inside the capsule was a canister that held the samples--ancient comet and interstellar dust particles that could hold possible clues to the early origins of the Solar System. The canister loosely resembled an oversized tennis racket and contained cells filled with Aerogel-- a substance so light it almost floats in air. During the brief encounter with Comet Wild 2, the sample tray with the Aerogel cells was exposed to capture the prized particles, and then retracted into the canister for its long journey back to Earth.
With great anticipation, the team then carefully removed the canister from the capsule. Stardust's Sample Return Canister was opened at a curation facility at JSC in Houston, Texas. It is here where science will again make history as the very first pristine comet and interstellar dust samples will continually undergo extensive investigation and analysis.
The fine dust and rocks in comets are best studied on Earth where complex instruments can be used to fully study the materials at scales approaching atomic spatial resolution.
Working in the cleanroom, scientists painstakingly activated and slowly opened the canister, exposing the sample tray, which held the Aerogel and trapped particles.
As a precaution, team members were prepared to catch any Aerogel pieces that might have become loose during any part of Stardust's interstellar journey. The sample tray was then secured to a stand, and the individual Aerogel capture cells were removed from the sample tray with a cell-removal tool.
In order to minimize damage, each cell was carefully removed and analyzed, paying particular attention to unique features, composition, size, and chemical properties. Each removed cell was placed in an individually marked box.
The need for laboratory study of samples from the Solar System's most primitive bodies was the inspiration for the NASA Stardust mission, the first NASA mission to return samples from space since the Apollo 17 Lunar mission in 1972.
These scientists will be the world's first to witness and analyze the fundamental building blocks of our Solar System and may be able to determine not only the origins of the Solar System from these samples, but also possibly the origins of life.
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