The Roman telescope has enough gas for 22 years, double NASA's expectations

NASA’s Nancy Grace Roman Space Telescope launched August 30 on a SpaceX Falcon Heavy and was delivered on such a precise trajectory that fuel usage so far is far below conservative estimates, giving the observatory enough hydrazine for at least 22 years of operations. Designers originally budgeted propellant for a minimum five-year mission plus a five-year extension; the first major course-correction burn used roughly 40 pounds (18 kg) of hydrazine versus a preflight allocation of 441 pounds (200 kg). Roman left Earth about two tons under its maximum allowable mass, letting ground teams load tanks to capacity with roughly 290 gallons of hydrazine feeding 24 thrusters. The spacecraft is headed to a quasi-halo orbit around Sun-Earth L2 and will take about three months to arrive; station-keeping burns are expected roughly every 28 days and reaction-wheel momentum dumps will use the propulsion system as needed.

The large fuel margin reduces near-term need for a robotic refueling mission, though Roman was built to be serviceable: it carries a grapple fixture, retroreflector and fueling-port features sized and magnetically closed to ease rendezvous and robotic refueling if a servicer ever becomes available to travel to L2. All systems have checked out well after launch - mirrors and all 18 near-infrared detectors on the Wide Field Instrument are cooling and returning good data, the coronagraph performed during initial checkouts, and Roman will deliver Hubble-like resolution over a field of view 100 times larger.