Goddard Helicopter Simulation of Venus Descent Imaging for Science

Goddard Space Flight Center and its Wallops Flight Facility (GSFC/WFF) conducted a Helicopter-based flight simulation of how a future probe or lander would conduct descent imaging of the surface of Venus for the purpose of new scientific understanding. This UH-1 Helicopter flight experiment simulated the free-fall landing of a Venus probe equipped with a nadir-oriented descent camera similar to those that have flown to Mars on the Mars Science Laboratory Curiosity rover (MARDI). By conducting various terminal descent trajectories at a nominal free-fall velocity anticipated for Venus for the final 1.5 km of descent to the surface with multiple nadir-pointing cameras and ancillary GPS and video documentation, a representative dataset was acquired for characterizing how descent images can be used to compute high resolution digital elevation models (topographic maps) at “human scales”(< 3m). The experiment was conducted over a large quarry in southern Maryland where bare rock, gravel, boulder-covered, and sandy surfaces with various topologies offered realistic analogues to the types of planetary surface landforms and deposits likely to occur in the enigmatic Venus highlands. Thanks to the adept flight performance of the WFF-based UH-1 helicopter (and its pilots) and the robust experimental design, over 12 flight trajectories for four different target types were successfully achieved with nearly 60 Gb of flight data, including detailed ground-based documentation. Independent WFF airborne lidar topography data was also made available thanks to the Operation Ice Bridge instrument calibration test flights over the identical quarry targets as independent “ground truth”. The results demonstrated how nearly vertical-baseline descent images can be used to generate sub-meter resolution digital topography maps (DEMs) with vertical resolutions as fine as 10-15 cm using the latest Structure-from-Motion (SfM) algorithms. The flight experiment demonstrated the value of terminal descent imaging for any planetary probe or lander mission and in particular the prospects for 3D map and imaging data at Venus that directly addresses key questions posed in the National Academy of Sciences most recent Planetary Decadal Survey. Furthermore, results included a 3 cm horizontal resolution digital topography model of a large boulder deposit representing some of the most rugged terrain conceivable of relevance to the safety of future landings on both Mars and Europa. The Venus-oriented helicopter flight experiment was supported by the senior leadership at GSFC and WFF as a feed-forward to new science possibilities for future missions to Venus. Special thanks to GSFC Center Director Chris Scolese and WFF Director William Wrobel. The PI for the flight experiment was GSFC’s Chief Scientist James B. Garvin and Chief Engineer was GSFC’s Steve Tompkins.