Astrobotic awarded NASA contracts to develop lunar lander technologies
NASA recently awarded Astrobotic two contracts that could help move the Pittsburgh-based company closer to making its first lunar landing. The contracts are for developing technologies for the company’s Peregrine lander, but could possibly make lunar landings easier and more accessible to others in the future.
The first contract is a $10 million “Tipping Point” award from NASA’s Space Technology and Mission Directorate for the development of a terrain relative navigation (TRN) sensor for precise lunar landings.
TRN is being designed to allow the spacecraft to land with unprecedented levels of accuracy at some of the most challenging landing sites on the Moon. These include areas of promising scientific exploration and compelling economic opportunity, such as lunar skylights and the permanently-shadowed ice-rich poles of the Moon.
Astrobotic is to lead the development in partnership with Moog Space and Defence, Moog Broadreach, NASA’s Jet Propulsion Laboratory and NASA’s Johnson Space Center. The TRN system is designed to use cameras and onboard maps to provide real-time vision-based navigation measurements and should enable a spacecraft to autonomously land within 328 feet (100 meters) of its target—an accuracy level vastly exceeding conventional landing systems.
“The culminating demonstration is a technology demonstration flight to the Moon,” Fraser Kitchell, director of Astrobotic’s Future Missions and Technology department, told SpaceFlight Insider. “We would be performing TRN as we descend to the surface of the Moon on a lander.”
Astrobotic is currently scheduled to launch its first Peregrine lander to the Moon on a United Launch Alliance Atlas V rocket sometime in 2020. The new TRN technology would fly aboard that lander, but only in a test mode.
“We’ll be collecting data and we will need to send that data back to Earth to validate that the sensor worked as expected,” Kitchell said. “But at least for the first mission, the system will not be fully integrated with the spacecraft or feeding measurements into the flight computer.”
Robotic landing systems on Earth use GPS for precise navigation. There is obviously no GPS on the Moon or any other celestial bodies. Astrobotic’s TRN system will have to rely on onboard cameras and computer vision algorithms to detect features on the Moon as the lander descends and match those features to specially-detailed onboard maps. High-speed image processing is expected to allow the system to continuously and accurately determine the spacecraft’s position as it descends.
“That’s really a big breakthrough for access to the Moon,” Astrobotic CEO John Thornton told SpaceFlight Insider, “because now we can land next to areas of scientific interest, or areas of challenging terrain, and know that we can hit the spot exactly where we call it.”
A crucial part of the TRN system is expected to be the development of an accurate and precise lunar map generator.
“We have a huge amount of imagery of the Moon,” Kitchell said. “The LRO (Lunar Reconnaissance Orbiter) has been sending back imagery for over a decade now. We have images of the lit surface of the Moon almost everywhere. But there are some challenges. If you are going to go to the poles of the Moon, and you want to land there and collect data in January of 2021, and you know your landing site, you won’t have images of what the landscape looks like from your trajectory and your approach to that landing site.”
Although LRO maps exist of all areas of the Moon’s surface, the areas at the poles are particularly problematic because of how different shadows appear on the surface at different times of the lunar day.
“The critical difference is that you don’t know what is going to be shadowed and unshadowed,” Kitchell said. “LRO hasn’t captured imagery for that lighting and that time of day. So what you have to do is build a very realistic digital elevation model of the Moon from the LRO data. And then you have to render it using a graphical renderer to basically produce an accurate map that has accurate lighting of the surface at that location and at that time.”
The recent NASA contract will allow Astrobotic to develop a tool that will make that lunar mapping imagery available not only to Astrobotic, but to others planning a trip to the Moon.
“The advantage here is that any future missions to the Moon will need those good maps,” Kitchell said. “We want to make a tool so that any mission planner can order a date and a landing location. They can say ‘I want you guys to make a map for this.’ And they may want 30-50 different landing sites at all sorts of different times. We can store all of that on board.”
Kitchell said that as the spacecraft approaches the surface, it would call up teh right map and perform the TRN.
“We see that as key to commercialization,” Kitchell said. “We have to lower the overhead of repeat missions.”
Astrobotic is also expected to benefit from a recently-awarded $1.9 million contract in partnership with Frontier Aerospace of Simi Valley, California. The contract is to provide flight qualification for Frontier’s Deep Space Engine (DSE) that utilizes “MON-25/MMH” propellant. Frontier is expected to provide five DSE thrusters for Astrobotic’s Peregrine lander. They will be integrated as part of the lander’s propulsion system, which is provided by Dynetics of Huntsville, Alabama.
“They are creating a MON-25 propulsion system that is good for deep space exploration,” Thornton said. “It is good for deep space journeys because of the way the fuel is stored. It is an easier fuel to store for those long-duration missions.”
MON stands for mixed oxides of nitrogen, an oxidizing agent for propulsion systems, with MON-25 denoting the mixture is 25 percent nitric oxide. MMH is monomethylhydrazine, a volatile hydrazine chemical that is used in propulsion systems because it is hypergolic (meaning it ignites upon contact) with various oxidizers.
The DSE engine’s use of MON-25/MMH is ideal for long duration missions in deep space because the mixture has a lower freezing point in comparison to other propellants. This enables the design of a propulsion system with lower power requirements, which translates to smaller, lighter, less expensive spacecraft systems.
These thrusters will be used for trans-lunar injection, several lunar orbit insertion deceleration burns, a breaking maneuver, and finally the spacecraft’s powered descent to the lunar surface.
“These engines are ideally suited to power our Peregrine lander and we are excited to prove their performance capability using our spacecraft,” said Astrobotic Mission Director Sharad Bhaskaran via press release. “We look forward to working with Frontier on a successful first mission.”
Video courtesy of Astrobotic Technology
Michael Cole is a life-long space flight enthusiast and author of some 36 educational books on space flight and astronomy for Enslow Publishers. He lives in Findlay, Ohio, not far from Neil Armstrong’s birthplace of Wapakoneta. His interest in space, and his background in journalism and public relations suit him for his focus on research and development activities at NASA Glenn Research Center, and its Plum Brook Station testing facility, both in northeastern Ohio. Cole reached out to SpaceFlight Insider and asked to join SFI as the first member of the organization’s “Team Glenn.”