Fuel Savings Double Potential Lifetime for NASA’s Roman Mission
The results are in: NASA’s Nancy Grace Roman Space Telescope’s very accurate first mid-course correction, along with other fuel savings, are expected to more than double the mission’s potential operational lifetime.
“As a result of exquisite planning by our orbital dynamics team, brilliant execution by the operations team, and a precise launch from SpaceX, Roman has fuel for at least 22 years of potential science operations,” said Jamie Dunn, center director at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The added life comes from the first mid-course correction’s accuracy, extra fuel added prior to launch, and anticipated results from Roman’s upcoming second mid-course correction and orbital insertion.
Original projected mission lifetime: 10 years
Roman was designed for a five-year primary mission, plus a five-year extended mission — a 10-year fuel budget in total. Because fuel is the observatory’s primary consumable resource, any fuel savings could enable additional years of observations beyond the 10-year design life.
First burn results: +4 years
The Roman team executed its first burn on Aug. 31 to adjust the observatory’s trajectory toward its final orbit and has since been analyzing its effects on the mission. In addition to being executed with more than 99% accuracy, the maneuver required less than 10% of the fuel the team had budgeted for: about 40 pounds (18 kilograms), down from the allocation of 441 pounds (200 kilograms).
Bonus fuel at launch: +4 years
Extra fuel loaded at launch could enable roughly four more years on top of that. This launch surplus exists because Roman launched lighter than planned: The team had budgeted fuel using a conservative maximum weight of 21,605 pounds (9,800 kilograms), well above the observatory’s actual weight of 17,760 pounds (8,056 kilograms). The lighter spacecraft needed less fuel for the mid-course correction, and its lower weight also left room to fill the propellant tanks beyond what the 10-year mission alone required.
“A spacecraft’s mass changes throughout the design and build process, so we base the propellant budget on a set maximum value so we won’t come up short,” said Alison Rao, the Roman propulsion lead at NASA Goddard. “We track the propellant needed based on actual mass throughout integration and testing as well, to make sure we have wiggle room. Since Roman’s was lower than we budgeted for, we were able to fill the propellant tanks to their capacity rather than only filling them as much as we needed to for the 10-year requirement.”
Upcoming burn, orbital insertion: +4 years expected
Thanks to the first mid-course correction’s success, the second burn is expected to be very small and save even more fuel. The team can also wait longer to conduct this follow-up burn, now planned for later this month. It will give the observatory the last bit of energy required to achieve its targeted position prior to maneuvering into its final orbit at L2, approximately 100 days after launch, or about early December. According to current projections, both maneuvers will use less fuel than planned, potentially saving even more for future science.
Once in orbit around L2, Roman will only require periodic station-keeping burns roughly every 28 days.
To learn more about Roman’s commissioning process, visit:
