Editor’s note: Updated at 3PM EST (2000 GMT) with a delay until Tuesday.
United Launch Alliance postponed the planned launch of an Atlas 5 rocket from Cape Canaveral on Sunday after kerosene fuel was discovered leaking into the launch pad’s ground storage system. Officials have rescheduled the launch of two US military satellites for Tuesday.
ULA announced the launch delay at around 7 p.m. EDT Saturday (0000 GMT Sunday), before the countdown to a planned takeoff begins before dawn Sunday.
«During initial operations, a leak was detected in the Rocket Propelant-1 (RP-1) ground storage system,» ULA said in a brief statement.
RP-1 is a high-precision kerosene fuel used in the first stage of the Atlas 5 rocket. The Russian RD-180 first stage engine consumes kerosene fuel in a mixture with supercooled liquid oxygen.
Kerosene fuel was to be loaded onto the first stage of the Atlas 5 Friday afternoon, after the rocket was launched from ULA’s Vertical Integration Facility to Launch Pad 41 at Cape Canaveral Space Force Station. But the fuel loading was delayed to Saturday, and the ULA did not say why the teams could not complete the operation on Friday.
The Atlas 5 launch team loads cryogenic propellant into the Atlas 5 a few hours before liftoff. The Centaur rocket’s upper stage consumes liquid hydrogen and ultra-cold liquid oxygen.
ULA initially rescheduled the launch for Monday, but officials announced Sunday afternoon that teams needed more time to test a fuel sample to make sure no kerosene was contaminated during the spill. ULA said repairs to the ground storage system were completed on Sunday afternoon.
The new target launch time is 4:04 a.m. EDT (0904 GMT) on Tuesday, the opening of a two-hour launch window, according to ULA.
The official launch weather forecast from the US Space Force’s 45th Weather Squadron predicts an 80% chance of weather suitable for liftoff early Tuesday.
The Atlas 5 rocket will be launched with two US Space Force satellites hosting a range of prototypes and technology experiments. Military engineers will test their readiness for use in future operational space missions.
The launch is sponsored by the Military Space Testing Program, which oversees many of the Department of Defense’s experimental space missions. The two largest satellites on the Atlas 5 rocket, called STPSat 6 and built by Northrop Grumman, host a NASA laser communications experiment and a National Nuclear Security Administration payload designed to detect nuclear explosions to verify compliance with an international treaty.
The military did not disclose details of other experiments on the mission, but officials said they will generally test technologies related to space field awareness, space weather monitoring and communications.
A flight-sharing satellite, dubbed Long Duration Propulsive ESPA, or LDPE 1, is also being put into orbit on an Atlas 5 rocket. It is mounted on the rocket below the STPSat 6 within the 17.7-foot (5.4-meter) payload aerodynamic.
LDPE 1 will host its own technology experiments, and will have its own propulsion system for maneuvering in space.
The Atlas 5 rocket will aim to launch both satellites into geosynchronous orbit more than 22,000 miles (nearly 36,000 km) above the equator about seven hours after liftoff.
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