Environmental Test Results for a Direct Laser Cryobot for Ocean World Missions
Abstract
Stone Aerospace has developed a novel ice penetrating technology for potential use on Ocean World ice shells and Martian polar ice. In a Direct Laser Penetrator (DLP) probe, light is carried from a laser source to a vertically descending ice penetrator via an optical fiber. The light is emitted from the nose of the vehicle as a focused beam, which melts the ice ahead of the probe. The optical energy is transferred directly to the ice and results in rapid and efficient descent, regardless of atmospheric pressure or ice temperature. We present results from environmental chamber tests of the ARCHIMEDES DLP probe, which uses laser light at a wavelength of 1070 nm.
Initial DLP tests used a scribed support rod attached to the aft end of the vehicle. These tests validated the ability of DLP to initiate and sustain penetration into ice at 77 K, under vacuum. In these tests, ice was sublimated and ejected from the borehole, producing a cone of re-frozen ejecta material radially distributed around the hole. Total energy use data, combined with measured descent rates suggest that, at least within 1 to 2 probe lengths of penetration into the ice, the probe is descending with less energy than would be needed for full sublimation. A possible explanation is that little energy is wasted in the vehicle sidewalls, leading to a reasonably cylindrical hole. The tight conformity of the hole with the probe body may allow sufficient vapor pressure to form ahead of the vehicle that liquid water forms temporarily. Eventually, the borehole closes behind the probe as sublimate refreezes to the sides of the hole. We will show new findings from DLP probes equipped with fiber spoolers that pay out the power fiber as the vehicle descends. Energy use and descent rate data will be presented. DLP is an efficient means of penetrating ice perhaps 10's of meters below a planetary lander. On Earth it shows promise as a high speed means of reaching the bottom of the Antarctic ice sheet. In order to test Ocean World technologies and instruments, a cryovac test chamber called Europa Tower has been built at the Stone Aerospace facility in Austin, Texas. This chamber contains a cylinder of water ice 2 m tall by 0.75 m in diameter and can be used to conduct experiments in ice at temperatures down to 77 Kelvin and pressures of 10E-3 Torr. This research was funded by the NASA ColdTECH program.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P53E3503S
- Keywords:
-
- 0728 Ice shelves;
- CRYOSPHERE;
- 6221 Europa;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6282 Enceladus;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6297 Instruments and techniques;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS