Astrobotic has announced a program to study advanced navigation techniques that could allow the next generation of spacecraft to target landings at some of the most interesting scientific destinations in the solar system.
Under a 15-month Small Business Technology Transfer (STTR) Phase II-X contract, managed by NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, Astrobotic will research and develop navigation software that could allow spacecraft to land safely and precisely on unmapped planetary bodies, and will specifically study techniques applicable to icy ocean worlds in the outer solar system, such as Saturn’s moon Enceladus, and Jupiter’s moon Europa.
Though the software will be designed to be applicable to a range of missions, spacecraft, and sensors, the team is working toward a landed mission on Enceladus, a small, ice-covered moon of Saturn, with both cameras and laser ranging sensors. Enceladus is a high-priority target for potential future life-finding missions because it appears to have all the ingredients thought to be required for life, including liquid water, chemical ingredients, and energy sources. At Enceladus the latter two ingredients are provided by active hydrothermal vents.
Some scientists believe that life originated on Earth at similar hydrothermal vents on the Earth’s seafloor. Additionally, the Cassini spacecraft detected a plume of water and organic molecules erupting from the moon’s South Pole, indicating that liquid water and ingredients for life may be accessible at the surface. A possible future mission that landed close to Enceladus’ geysers, which likely directly originate from a liquid ocean beneath the surface, could carry life-detecting sensors and seek to answer the question of whether life exists on the moon, and potentially whether life arose more than once in our solar system.
Astrobotic will develop software to help spacecraft on possible future missions land near unmapped or dynamic scientific targets in the solar system, including close the south pole of Saturn’s icy moon, Enceladus. The Cassini spacecraft captured images showing plumes erupting from the moon’s surface (left) during multiple fly-bys of the moon. Scientists believe these plumes are the result of active thermal processes occurring in a salty, subsurface, global ocean (artist’s concept, right). Images courtesy NASA/JPL-Caltech.
Despite the scientific appeal, Enceladus presents novel and significant challenges to a landed mission. Traditionally, to land a planetary spacecraft precisely and safely, mission planners require detailed orbital imagery of the surface to select a landing site and guide the spacecraft to that site. However, because orbital imagery often requires a precursor orbiter to gather the images, at least two spacecraft are needed to explore a single target, increasing mission costs and slowing the pace of discovery. In the case of an outer planet moon such as Enceladus, this could mean of delay of many years to decades and billions in additional costs.
The program will generate the data and analyses required for mission designers to plan SLAM-guided landings to small, unmapped planetary bodies and reduce the cost of exploration of the outer bodies of our solar system. The technology will be demonstrated during a culminating field demonstration on an icefield in Alaska in late 2019.
In addition to programmatic considerations, another issue with relying on precursor imaging is that orbital imagery may not have the resolution required to determine if the most interesting scientific destinations are close to suitable landing sites. And, even if the imagery does have sufficient resolution, mission planners must consider whether sites close to active geysers and fracturing ices are likely to remain safe for a duration of time.
To address these issues, Astrobotic is researching whether a spacecraft could build a map of a landing location while it descends to the surface, and will work to adapt the company’s Simultaneous Localization and Mapping (SLAM) software toolset, AstroNav, to the challenge.
In addition to icy ocean worlds, the landing research could also apply to precision landings at unmapped landing sites on planetary surfaces shrouded in dense atmospheres, such as Saturn’s largest moon, Titan, or for landings in regions of Earth's Moon shrouded in darkness.
This research builds on Astrobotic’s lunar subterranean exploration software, which was developed under a Phase II STTR contract managed by NASA’s Kennedy Space Center in Florida, and on Astrobotic’s terrain relative navigation and hazard detection and avoidance software, which have been demonstrated on propulsive vehicle flights in prior tests contributed by NASA’s Flight Opportunities program.
Kerry Snyder, Principal Investigator and Senior Research Engineer at Astrobotic. said that in prior work, the company demonstrated that AstroNav could provide precise navigation to free-flying platforms in GPS-denied, unmapped underground environments. The firm's software has been designed to be adaptable and we believe that it can be extended to applications such as orbit determination and landings on unmapped, planetary surfaces.
Fraser Kitchell, Astrobotic’s Director of Future Missions and Technology, noted that the potential implications of this research are thrilling, and the company is honored to get the chance to work with JPL on this contract,. JPL has delivered the most advanced planetary landings in history, and this research contract gives Astrobotic a chance to work with the best in-space navigation researchers in the world.