SpaceX cargo mission grounded to investigate potential fuel leak – Spaceflight Now

The SpaceX Dragon cargo ship approaches the International Space Station on August 3. 30, 2021. Credit: NASA

SpaceX has postponed this week’s planned launch of the Dragon Cargo mission to the International Space Station to investigate a possible leak discovered while refueling the spacecraft at Cape Canaveral.

The Dragon spacecraft was scheduled to launch Friday morning from NASA’s Kennedy Space Center in Florida. Officials have not set a new target launch date for the SpaceX resupply mission, but a NASA spokesperson confirmed that it won’t happen Friday or Saturday.

NASA said in a statement that SpaceX detected “elevated vapor readings” of monomethyl hydrazine, or MMH, fuel in an “isolated area” of the Dragon spacecraft’s propulsion system during fuel loading ahead of this week’s launch.

Refueling the Dragon spacecraft is one of the final steps to prepare the capsule for flight, usually before SpaceX moves the craft to the launch pad for integration with its Falcon 9 rocket.

The Dragon spacecraft has propellant tanks containing hydrazine fuel and nitrogen tetroxide oxidizer. The two thrusters ignite on contact with each other, providing thrust to the cargo ship’s Draco thrusters used for in-orbit maneuvers.

Each Dragon spacecraft contains 16 Draco thrusters, which are small rocket motors that generate about 90 pounds of thrust. Draco engines are used for orbit-adjustment burns and to control the spacecraft’s approach to the space station, then fired at the end of the mission for a deorbit burn to direct the capsule into the atmosphere to return again and spray.

SpaceX’s ground handling team, working at the Dragon Regeneration facility at Cape Canaveral Space Force Station, unloaded the fuel and oxidizer payload from the spacecraft’s area with elevated hydrazine vapor readings, NASA said.

Multiple sources told Spaceflight Now that a hydrazine fuel leak may be the cause, but NASA said the source of the steam has not yet been determined.

“Once the exact source of the elevated readings has been identified and the cause identified, the joint NASA and SpaceX teams will identify and announce a new target launch date,” NASA said in a statement.

The Dragon spacecraft for the upcoming C208 cargo mission is assigned to SpaceX’s fleet of reusable capsules. The spacecraft has flown to the space station twice before, most recently on a 32-day resupply mission this past August and September.

The Dragon’s next resupply mission, known as CRS-25, will be SpaceX’s 25th cargo flight to the space station under contract with NASA.

The Dragon capsule on the CRS-25 mission will provide more than 4,500 pounds of food, supplies and experiments to the orbiting research laboratory.

The spacecraft will also transport an Earth science instrument to the station to monitor the mineral composition of dust particles in desert regions around the world. Developed at NASA’s Jet Propulsion Laboratory, the Earth’s Surface Mineral Dust Source Investigation Tool, or EMIT, the instrument is already installed inside the unpressurized Dragon space box for ride to the space station.

The EMIT instrument will be removed from the Dragon’s torso using the space station’s robotic arm, and then installed on an experimental platform outside the complex. The data collected by the tool will help scientists learn more about how dust transported into the atmosphere from deserts affects Earth’s ecosystems and human health.

While the Dragon Cargo launch is on hold, SpaceX is pressing ahead with plans to launch another Falcon 9 this week with the Egyptian communications satellite Nilesat 301. Nilesat 301 is scheduled to take off on Wednesday from Cape Canaveral as the launch window opens at 5:04 p.m. ET US Eastern (2104 GMT).

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