How do you get a core sample from a comet? There's so little gravity that if you used a scoop or a drill, you'd push yourself right off the surface. To solve this problem, we came up with a harpoon that collects samples. The concept is that the spacecraft flies next to the moving comet and fires from about 30 feet away, we would use a dampening system and propulsion to counteract the recoil. Our prototype harpoon is stainless steel, about one foot long, two inches wide and four pounds. We don't want it to be too lightweight, because it needs momentum to cut through the comet's surface. The harpoon hits the comet with its tip open, the material fills an internal cartridge, and a garage-door-like mechanism shuts behind it.
Right now we're testing the harpoons in a laboratory. We can't use a cannon indoors—it's too dangerous—so we use a ballista, a large crossbow. We shoot harpoons at 100 feet per second into 55-gallon drums filled with beach sand, rock salt and pea gravel. Comets can be as soft as cotton candy or as dense as bedrock, so it's important that our harpoons work on a range of materials.
Comets are thought to contain some of the building blocks for life, so by taking a sample, you not only learn about the solar system's formation, but you could also find clues to the origin of life on Earth. There are not many jobs that combine comets, harpoons and the origin of life. And even on a bad day, you still get to fire a ballista.
—Don Wegel, a cryomechanical engineer at NASA's Goddard Space Flight Center
Where do I sign up?? Oh, and we need a bigger lab! :-)
Cant Popular science do better than that a drawing made off of a napkin he used to write it down from hearing it here off your blog or on Space.com's blog, I been talking about this idea for over 7 years with real rendered designs using AutoCad of how it would work. Another idea stolen off the free exchange of ideas off of blogs that they call their own...
How, when, and why, huh? So, not when we want to play baseball with it? Why is that? Because you can't hit a home run with some of them; which makes for bad TV. Right. Self explanatory and I shouldn't have needed to ask.
@ rlb2; So what were your favorite methods of acquisition and vector control out of the methods you explored?
They have my permission to use this one that I found in an old archive.
Note it is one I designed for sample return by harpooning a comet.
Why not use barbed harpoons to anchor the spacecraft to the comet and then drill the core sample?
This way the core sample can get to a decent depth.
See life in all its beautiful colors, and
from different perspectives too!
Ron Bennet, do you work at Goddard?
dw123 - I worked at Boeing for over 12 years, I've seen a lot of stuff there from commercial airplanes, rockets, space, military aircraft, etc, etc. I got three engineering degrees but I am still trying to figure out what I want to be when I grow up. I have my own business now, I also contract out for Honeywell Aerospace. Right now I'm not that busy by my own design as you can tell from all the post I've been posting here, taken some badly needed time off.
I've been at NASA for 10 years. I designed the sample collecting harpoon and am the lead engineer on this project. We did not use your ideas. We've been working on this for many years. Popular Science asked for the napkin-like drawings; they thought it would be an interesting way to illustrate the story and most people agree. We have CAD drawings, hardware, test beds, and a working prototype. Don't worry, we're on top of it =)