Sample Return Systems for Extreme Environments R. M. Winglee 1 , C. Truitt 1 , and R. Hoyt 2 Department of Earth and Space Sciences, University of Washington; 2 Tethers Unlimited inimizing Delta V urviving the Impact 0 2 4 6 8 10 12 14 0 50000 100000 150000 200000 250000 Compression Testing: Initial Sample Size 70 X 70 X 16 mm Hexcel (20 gm) Hexcel + Foam Epoxy (34gm) with Kevlar 1.0 in spacing (45 gm) with Kevlar 0.5 in spacing (50 gm) with Kelvar 0.25 in spacing (65 gm) Distance Compressed (mm) Compression Force (kN) NIAC Phase I Sample Return Sample return missions provide detailed information about the evolution of our solar system, but current approaches make them an expensive affair. The present soft landing method requires that fuel takes up a significant amount of mass of the spacecraft due to large changes in the spacecraft’s velocity. By reducing the spacecraft’s Delta V, sample return missions become more affordable and offer the potential to collect kilograms of material from multiple targets instead of grams from a single location. Sample Return Container Crumple Zone Penetrating Nose Cone ultiple Samples NIAC Phase II Sample Return Penetrator (Gravedigger) Flow Stagnation Increasing Sample Yield Acknowledgments A ground penetrator can use a spacecraft’s momentum for a hard landing, eliminating the need to slow or stop the spacecraft. Material flows through the penetrator during impact, and the sample return container is returned from the surface via a high strength tether. Honeycombed aluminum provides protection for the sample return container during impact. The honeycomb’s strength can be dramatically increased through the use of various additives. Equipping a spacecraft with multiple penetrators opens the possibility of either collecting samples from more than one location on a single body, or collecting samples from a number of different objects. Multiple penetrators with independent tethers envisioned on a concept spacecraft. Phase I field testing was conducted in March 2013, in the Black Rock desert in Nevada. The two impacts created very different impact shafts: the subsonic impact produced well defined slickensides (1d); the supersonic impact shaft walls experienced an oscillating diameter, but was badly charred from remaining propellant in the solid motor (2c). 1a 1b 1c 1d 2a 2b 2c Phase II field testing was conducted on a private ranch in California during late December 2014, and consisted of three separate flights. Gravedigger 3 Preliminary Results: • Low Velocity impact (subsonic) • Impact angle ~10˚ from normal • Penetration depth ~ 1 meter • Sample was collected, but stagnation resulted in low yield Gravedigger 4 Preliminary Results: • High velocity impact (~340 m/s) • Impact angle ~80˚ from normal due to issue with ignition timing • Penetration depth ~1.8 meters • Sample was collected, but stagnation resulted in low yield Gravedigger 5 Preliminary Results: • High velocity impact (~400 m/s) • Impact angle ~5˚ from normal • Penetration depth ~1 meter • No sample collected due to feed chimney structural failure Pressure gradients during impact rapidly decrease, and while fine ejecta is captured in the sample return container, the bulk of the material is clogging the feed chimney at about one third of the penetration depth. This is limiting the sample yield from the desired kilograms to a few grams. The stagnation point can be seen on the right. Sample Return Container Fine ejecta captured in a backflow baffle inside Sample Return Container Stagnation Point Gravedigger 1 Results (1a-c ): • Demonstrated survivability of the system • Impact velocity <200 m/s • Impact angle ~30˚ from normal • Penetrating depth of ~1.5 meters • No sample, feed ports did not open Gravedigger 2 Results (2a-b): • Impact velocity ~400 m/s • Impact angle ~10˚ from normal • Penetration depth of ~ 2 meters • Potential seismic mapping capability • Sample collected, but badly charred In the next design evolution, the two current nose cone designs will be combined to increase the flow rate of material through the system. Relative flow velocity modeling suggests that by tapering the center bore and combining both feed port configurations, higher flow velocities can be reached than the current geometry allows. We would like to thank NIAC for providing the funding that has allowed this research to be conducted, Thomas Swett and Laurie Lord for providing us with proving grounds, and the students and volunteers with the UW ESS High Power Rocketry class for all their efforts and support. In addition we thank Robert Hoyt and his crew at Tethers Unlimited for helping us with the tether dynamics that make recovering our samples possible.
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Sample Return Systems for Extreme EnvironmentsR. M. Winglee1, C. Truitt1, and R. Hoyt2
1Department of Earth and Space Sciences, University of Washington; 2Tethers Unlimited
Minimizing Delta V
Surviving the Impact
0 2 4 6 8 10 12 140
50000
100000
150000
200000
250000Compression Testing: Initial Sample Size 70 X 70 X 16 mm
Hexcel (20 gm)
Hexcel + Foam Epoxy (34gm)
with Kevlar 1.0 in spacing (45 gm)
with Kevlar 0.5 in spacing (50 gm)
with Kelvar 0.25 in spacing (65 gm)
Distance Compressed (mm)
Com
pres
sion
For
ce (k
N)
NIAC Phase ISample ReturnSample return missions provide detailed information about the evolution of our solar system, but current approaches make them an expensive affair. The present soft landing method requires that fuel takes up a significant amount of mass of the spacecraft due to large changes in the spacecraft’s velocity. By reducing the spacecraft’s Delta V, sample return missions become more affordable and offer the potential to collect kilograms of material from multiple targets instead of grams from a single location.
Sample ReturnContainer Crumple Zone
PenetratingNose Cone
Multiple Samples
NIAC Phase IISample Return Penetrator (Gravedigger)
Flow Stagnation
Increasing Sample Yield
Acknowledgments
A ground penetrator can use a spacecraft’s momentum for a hard landing, eliminating the need to slow or stop the spacecraft. Material flows through the penetrator during impact, and the sample return container is returned from the surface via a high strength tether.
Honeycombed aluminum provides protection for the sample return container during impact. The honeycomb’s strength can be dramatically increased through the use of various additives.
Equipping a spacecraft with multiple penetrators opens the possibility of either collecting samples from more than one location on a single body, or collecting samples from a number of different objects.
Multiple penetrators with independent tethers envisioned on a concept spacecraft.
Phase I field testing was conducted in March 2013, in the Black Rock desert in Nevada.
The two impacts created very different impact shafts: the subsonic impact produced well defined slickensides (1d); the supersonic impact shaft walls experienced an oscillating diameter, but was badly charred from remaining propellant in the solid motor (2c).
1a
1b 1c
1d
2a 2b
2c
Phase II field testing was conducted on a private ranch in California during late December 2014, and consisted of three separate flights.
Gravedigger 3 Preliminary Results:• Low Velocity impact (subsonic)• Impact angle ~10˚ from normal• Penetration depth ~ 1 meter• Sample was collected, but stagnation resulted in low
yield
Gravedigger 4 Preliminary Results:• High velocity impact (~340 m/s)• Impact angle ~80˚ from normal due
to issue with ignition timing• Penetration depth ~1.8 meters• Sample was collected, but stagnation
resulted in low yield
Gravedigger 5 Preliminary Results:• High velocity impact (~400 m/s)• Impact angle ~5˚ from normal• Penetration depth ~1 meter• No sample collected due to feed
chimney structural failure• Sample return container intact and at
surface of impact
Pressure gradients during impact rapidly decrease, and while fine ejecta is captured in the sample return container, the bulk of the material is clogging the feed chimney at about one third of the penetration depth. This is limiting the sample yield from the desired kilograms to a few grams. The stagnation point can be seen on the right.
Sample Return Container
Fine ejecta captured in a backflow baffle inside Sample Return Container
Stagnation Point
Gravedigger 1 Results (1a-c):• Demonstrated survivability of the system• Impact velocity <200 m/s• Impact angle ~30˚ from normal• Penetrating depth of ~1.5 meters• No sample, feed ports did not open
Gravedigger 2 Results (2a-b):• Impact velocity ~400 m/s• Impact angle ~10˚ from normal• Penetration depth of ~ 2 meters• Potential seismic mapping capability• Sample collected, but badly charred
In the next design evolution, the two current nose cone designs will be combined to increase the flow rate of material through the system. Relative flow velocity modeling suggests that by tapering the center bore and combining both feed port configurations, higher flow velocities can be reached than the current geometry allows.
We would like to thank NIAC for providing the funding that has allowed this research to be conducted, Thomas Swett and Laurie Lord for providing us with proving grounds, and the students and volunteers with the UW ESS High Power Rocketry class for all their efforts and support. In addition wethank Robert Hoyt and his crew atTethers Unlimited for helping us with thetether dynamics that make recoveringour samples possible.
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