WASHINGTON — Revised concepts for a proposed Europa lander mission could reduce its mass and cost by simplifying its science requirements and doing away with a dedicated communications relay.
In a presentation at a meeting of the Committee on Astrobiology and Planetary Science of the National Academies March 28, Kevin Hand of the Jet Propulsion Laboratory said that feedback from a mission concept review for the proposed lander last June led to changes in the design to reduce its cost.
“The technology and science were well received. The marching orders that we got out of that review were to see if we could simplify the architecture to reduce complexity and cost,” he said. While there’s been little discussion of the lander’s cost, Hand said there was a “desire” to reduce its cost to below $3 billion.
The concept for the mission presented at that review involved the launch of the lander on a Space Launch System rocket no earlier than late 2025. The spacecraft would enter orbit around Jupiter in 2030 with a landing on Europa to follow no earlier than December 2031. The battery-powered lander would operate on the surface for at least 20 days, relying on a communications relay spacecraft in orbit to return data to Earth.
Hand said the project team looked at options to do away with the relay spacecraft by giving the lander a larger antenna to enable direct-to-Earth communications. That concept uses a flat-panel antenna 80 centimeters across, versus antenna smaller antennas 30 to 40 centimeters across intended for communications with the relay. One quadrant of that larger antenna has been built and tested at JPL, he said, with “encouraging” results.
Another factor that enables the change in design, he said, is a shift in the science requirements for the lander. A report by a science definition team last year had included, as one of the mission’s priorities, the ability of the lander’s instruments to directly detect any life that might exist in the moon’s icy surface.
“That’s a very high bar,” Hand said. “That bar runs the risk of setting expectations too high, perhaps, and also potentially cannibalizing some of the other science that the community sees as very valuable.”
Instead, the mission team looked at what the “sweet spot” for science from the lander mission might be. Hand said that looking for biosignatures of past or present life would simplify the science requirements for the mission, including reducing the amount of data needed to be transmitted back to Earth.
“By moving to biosignatures, we are able to reduce that need for a dedicated comm relay, which enables a direct-to-Earth architecture, which is less costly and less complex,” he said. That approach also preserves the proposed instrument payload that supports both biosignature and other science. “We worked very hard not to remove any instruments.”
He added that by focusing on biosignatures, the lander does not necessarily lose the ability to directly detect life, only that it no longer drives the design of the mission. “If you choose your instruments and your investigations wisely, you have the capability of doing life detection, but you are unburdened from some of the requirements of life detection.”
Another change in the lander is a shift away from the avionics being developed for the Europa Clipper multiple-flyby mission. That was intended to save money but resulted in driving up the mass of the lander. Hand noted that a one-kilogram increase in the mass of the lander on the surface of Europa translated into a 30-kilogram increase in the mass of the spacecraft on the launch pad, given the mission’s fuel requirements.
While refining the design of the lander and its science requirements, other work is in progress on the mission’s technology. That includes development of a “terrain relative navigation” system for precise landings on the surface and cryogenic sampling technologies to efficiently cut into Europa’s cold, icy surface to collect samples.
These efforts have continued despite the lander being caught in a tug-of-war between NASA and Congress. NASA requested no funding for a lander mission in its 2018 budget proposal, focusing instead on the Europa Clipper mission. However, the 2018 omnibus appropriations bill signed into law March 23 included $595 million intended for both Clipper and the lander mission, although not specifying how that money should be allocated between the two. NASA’s fiscal year 2019 budget proposal again requested no funding for the lander.
Hand said he would like to move ahead with selection of instruments for the lander, allowing engineers to design around actual hardware rather than concepts for instruments included in the science definition team report. “We have developed the systems as much as we can for generic applications,” he said. “To take it to the next level, we will need to work with real instruments. That’s what I would hope to see in the next year.”
Jim Green, director of NASA’s planetary science division, agreed. “We feel that one of our next major hurdles is instrumentation, and figuring out our next steps in terms of investing in those,” he said, with a meeting planned at NASA Headquarters next week to discuss some of those options.
“I think you’ll see now that the budget is passed, with congressional direction, we’ll be smartly out in a couple of these areas,” Green said.