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PlanetVac: Sucking Up Planetary Regolith

A New Planetary Society Project

Posted by Bruce Betts

30-10-2012 14:27 CDT

Topics: Planetary Society Projects, PlanetVac, future technology, the Moon, Mars, near-Earth asteroids

I am excited to introduce to you the latest Planetary Society project: PlanetVac (Planetary Vacuum), a project with Honeybee Robotics.  PlanetVac is new technique to sample planetary regolith (the upper surface materials that overlie bedrock).  It has the potential to be comparatively low-cost and very reliable due in part to a lack of moving parts.  It can be used on Mars, the Moon, or asteroids.  It could facilitate a rapid and reliable way to either get samples into in situ instruments on the spacecraft, or into a sample return capsule. 

PlanetVac uses a puff of pressurized gas to push regolith into a sample container (effectively acting like a planetary vacuum cleaner).  Because of the low pressures on Mars, the Moon, and asteroids, the technique is extremely efficient because the efficiency is related to the ratio of the pressure of the gas you are using to the ambient pressure.  Landers typically have high pressure Helium already on board, used to pressurize the fuel tanks, which could be used as the gas.

PlanetVac Sample Implementation with Lander

Honeybee Robotics

PlanetVac Sample Implementation with Lander
Diagram of how PlanetVac works showing a sample spacecraft: (1) Compressed gas cylinder releases a pulse of gas that (2) travels down lander leg strut and is (3) expelled through lander leg pad nozzle into regolith, (4) pushing regolith up a second leg strut to (5) sample intake manifold where it is then put into (6) sample return canister with other samples (or alternatively put into an in situ instrument).

The next crucial step with PlanetVac is to take it from theory and piece meal tests to a full up test in Honeybee’s 3.4 meter (11 foot) vacuum chamber.  If we can experimentally demonstrate the technique is effective, then it has the potential to move to higher levels of development and to become another arrow in the quiver of tools available to sample planetary surfaces.

Honeybee Robotics Vacuum Chamber

The Planetary Society/Bruce Betts

Honeybee Robotics Vacuum Chamber
The 3.4 m (11 ft) vacuum chamber and associated equipment at Honeybee Robotics that will be used to test PlanetVac prototype system.

To learn more about PlanetVac, you can read the write-up below from the project principal investigator, Kris Zacny, the Director of the Exploration Technology Group of Honeybee Robotics; or listen to Kris on Planetary Radio; or check out the video of Kris and me at Honeybee’s cool Pasadena facility last week talking about PlanetVac.  The video, shot by Mat Kaplan, is below.  In the near future, we’ll also have a video or two up about the other things Honeybee has been and is involved with.  I’ll link them here when they are available.  Honeybee built the rock abrasion tools (RAT) for the Mars Exploration Rovers, the scoop for the Phoenix lander, and the brush and portions of the sampling system for MSL Curiosity.  They are world leaders is sample manipulation on planetary surfaces.
Please consider supporting the PlanetVac project. 

The Planetary Society is seeking $30,000 to support the activities at Honeybee Robotics on PlanetVac prototype development and testing.  You can contribute here.

What is the PlanetVac project, from Kris Zacny:

We will design and build a prototype planetary lander with the pneumatic sample acquisition system - PlanetVac.  This revolutionary sampling approach relies on acquisition of planetary regolith into hollow sample tubes placed underneath the lander footpads. A puff of gas directed at the tube's rim and up the tube can effectively move acquired plug of regolith through the connecting hose and into a sample return container or analytical instrument for in-situ analysis. PlanetVac has no moving parts and in turn is very robust. Redundancy is provided by integrating sampling tubes below each lander foot pad.  Initial tests conducted in reduced gravity flights and in vacuum chambers demonstrated unprecedented efficiency: with just 1 gram of gas up to 6000 grams of soil was lofted at high velocities. This end to end sample acquisition and transfer system solves one of the most difficult problems in planetary exploration: sampling and transferring of a sample to an instrument.

PlanetVac Lander Leg Diagram

Honeybee Robotics

PlanetVac Lander Leg Diagram
Detail diagram of how PlanetVac works showing a lander leg example including close up: (1) Gas flow down lander leg strut from gas cylinder, to (2) outer tube of collection nozzle, to (3) side holes in inner tube of collection nozzle, forcing regolith up the inner tube through the lander leg strut (4), and up to a science instrument or to a sample return capsule container.

Once designed and built, the prototype PlanetVac will be placed inside our 3.5 m vacuum chamber for drop testing under Mars and Lunar/Asteroid vacuum conditions. The lander will be dropped onto a bed of Mars Mojave Simulant (MMS) and also onto a bed of JSC-1a Lunar soil simulant. Upon 'landing', a gas valve will direct pressurized gas into sampling tubes, by then already filled with the regolith. The regolith will then be seen moving through the clear tubing into a sample return container placed within the earth return vehicle (e.g. rocket nose cone). The basic operational principles have been established and tested.  However, to this day, no one has been able to put all the pieces together and perform end to end test under analog conditions. This will be the first!

Once proven, this approach would open up a new window to planetary exploration. PlanetVac could be used as a touch and go sampler for asteroid exploration, a hopper on the Moon - acquiring multiple samples every time it hops, or on Mars to acquire samples.

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See other posts from October 2012

 

Or read more blog entries about: Planetary Society Projects, PlanetVac, future technology, the Moon, Mars, near-Earth asteroids

Comments:

vjkane: 10/30/2012 03:39 CDT

This sounds like an ideal solution for cometary surface sampling (unless retaining the stratigraphic structure intact is a requirement). Would seem to be robust for different surface hardnesses, which has been a key problem in designing comet sampling systems.

energik: 10/30/2012 04:41 CDT

This sounds pretty similar to OSIRIS-Rex's TAGSAM, although the exhaust and sample collection are not going through the same path. http://osiris-rex.lpl.arizona.edu/?q=spacecraftpayload/tagsam But 6kg per gram of He sounds very (too?) impressive.

Bruce Betts: 11/26/2012 04:52 CST

Here is a response from Kris Zacny comparing PlanetVac and TAGSAM: "Osiris is using a surface filter (sort of a car 'air filter'). The filter is pressed against a surface and gas injected in the middle to stir up the surface regolith. As regolith escapes through the filter, larger particles get trapped in the mesh. The bottom of this filter also has sticky surface for getting some more material. Osiris is essentially sampling near surface regolith and captures mostly large particles while fines escape. If you want a sample, you need to bring an entire filter with you, and the arm has to move the filter into the earth return capsule. PlanetVac on the other hand, delivers sample directly to where you want it and also acquires all particle sizes and from much deeper. You may be able to preserve stratigraphy as well."

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