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Since the beginning of the

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space age NASA has explored our solar system, bringing back

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unprecedented scientific knowledge, but only a handful of missions

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over the past 50 years have actually collected and returned samples

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from these far off places. Astronauts

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on the Apollo program traveled to our Moon, bringing back over 800 lbs

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of moon rock. Stardust was an unmanned mission that collected samples

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from the coma of comet Wild 2 before returning them to Earth for in-depth

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scientific study. OSIRIS-Rex is the most recently funded

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sample return mission that will launch in 2016 and return surface

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samples from an asteroid in 2023.

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The Comet Nucleus Sample Return mission will collect subsurface samples

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from a comet and return them to Earth. Comets and Asteroids are

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leftover remnants from the early solar system and by studying samples from these

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objects, we can learn more about the formation of our solar system and

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may find clues to the origin of life on Earth. Collecting a sample

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from a comet is a challenging feat for many reasons, including how far

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away they are from Earth and how little gravity they provide. In our

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concept, harpoons are used to collect and retrieve samples from interesting locations

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on these exotic objects. Traditionally,

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when collecting samples on Earth, we use scoops, shovels, or coring drills,

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but on comets and asteroids there is so little gravity that you would

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push yourself off the surface if you used one of these methods. Harpoons allow

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you to grapple to the surface while taking a sample, allowing rapid sample collection

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and retrieval. First, we choose a specific interesting

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area to take a sample from and then fire a sample collecting harpoon into that

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spot. As the harpoon penetrates into the comet, it fills its inner sample

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cartridge with subsurface material as it goes deeper. When it reaches its

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maximum depth the sample cartridge closure mechanism shuts, trapping all

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the material inside it. The sample cartridge is then with drawn from the outer harpoon

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sheath and pulled back into the space craft. The sample is

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then brought back to a terrestrial laboratory where scientists examine the collected

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samples in a pristine environment.

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Before we journey here, we need to work here

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in the lab, studying comet and asteroid analogs.

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In order to determine how much energy is required to penetrate different depths

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in various density material, we’ve designed and built a harpoon

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test laboratory.  Although the actual mission will use a cannon,

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for safety reasons, we’ve employed a ballista to fire the harpoons.

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By correlating the imparted energy versus the penetration depth, we will

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know how to size the explosive charge for the actual mission.

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The harpoon lab also allows us to study how the tip geometry, cross

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section and mass of the harpoon affect its penetration.

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This has allowed us to optimize the harpoon sheath for a range of

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possible comet densities. Although sample return missions can be quite

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costly and complex, they offer important advantages over missions

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that study their subjects from a distance. Sample return missions allow

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terrestrial laboratories to study in far greater detail, with a variety