Crashing rockets could lead to novel sample-return technology

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Is it supposed to look like that? In this case, yes (Photo:Steve Jurvetson)

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The terms "auger in" and "lawndart" refer to rather exciting and decidedly dangerous methods of recovering a rocket, during which the screaming rocket buries its pointy end deep in the ground. Such over-enthusiastic landings provided a group of research students from the University of Washington (UWash) the inspiration for a new approach to collecting samples from hostile environments, such as the crater of an erupting volcano or a melting nuclear reactor.

UWash offers an upper-level undergraduate class called Rockets and Instrumentation. Taught by Professor Robert Winglee as a "hands-on course for the development of rockets and their instrumentation," the essence is to design and build a high-power model rocket with a science package and telemetry capability. At the end of the quarter, the class participants take their finished rockets to a firing range for the ultimate test.

While most of the rockets perform well, there is the occasional problem. After seeing a number of sub-optimal landings (of the lawndart variety) over the years, Prof. Winglee began to wonder if something useful could be rescued from the remarkable ability of rockets to bury themselves deep in the ground.

He conceived what is now the Sample Return Systems for Extreme Environments (SRSEE) project, for which he obtained NASA support through the Innovative Advanced Concepts program (NIAC). The basic concept is to collect and recover physical samples by deliberately crashing rockets into the material to be sampled. SRSEE is being carried out in partnership with Robert Hoyt's Tethers Unlimited. The project is currently at Phase II, which brings with it roughly US$500,000 of support over an 18-24 month period.

A rocket will impact and bury itself in a surface. In the process, ports on either side of the nose cone collect samples of the material near the surface. These samples will be collected in an interior capsule that can be removed from the rocket, using a method such as pulling on a tether. The tether would be attached to a recovery vehicle, perhaps a balloon or helicopter if working in an atmosphere, or a rocket-propelled vehicle in space, which would reel in the capsule to recover the sample. This hard impact sampling system would be far simpler than an attempt to make a soft landing in treacherous situations.

In space, there is another approach to pulling the tether, which is to put a spacecraft into a very slow (perhaps a foot per second) pass by the object to be sampled, and fire the sampling rocket before reaching the point of closest approach. When the spacecraft and the object, each following their own slightly different trajectories, drift apart, the tether will pull the sample capsule from the lawndart sampler.

In recent tests at Black Rock desert in Nevada (see video below), rockets were fired into the ground from a kite at an altitude of 3,000 feet (915 m). The test altitude was not high enough, as the rockets struck the ground while still under full thrust. However, they had broken the sound barrier, and components of the system survived the supersonic impact.

The next round of tests will begin at a higher altitude, and impact speeds of Mach 2 are expected.

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