Due to a potential propellant leak in spacecraft Draco thrusters, NASA and SpaceX are delaying the launch of cargo Dragon mission to the International Space Station.
According to NASA, in a statement issued late June 6, they are postponing the launch of the CRS-25 mission after detecting "elevated vapor readings" of monomethyl hydrazine (MMH) in a portion of the spacecraft's Draco thruster system, according to Space News.
Propellant Problem is Currently Under Investigation
The launch was initially scheduled for June 10. As of writing, the cause of the elevated reading is under investigation.
The Draco thrusters is being used by the Dragon spacecraft for orbital maneuvers. This includes approaching and departing the space station, and deorbiting at the end of the mission.
MMH and nitrogen tetroxide propellants, a storable, hypergolic combination, are used by the thrusters. Space News said that "the cargo version of Dragon lacks the more powerful SuperDraco thrusters SpaceX developed for the abort system on the Crew Dragon spacecraft."
According to NASA, when propellant was being loaded into the spacecraft the elevated readings were detected. However, the agency did not specify when it took place, they just said that the problem was identified over the weekend.
According to NASA and SpaceX, to discuss the issue and the best path forward, they met last June 6.
NASA said that in order to allow engineers to investigate the issue, the MMH and nitrogen tetroxide propellants had been offloaded from Dragon.
"Once the exact source of the elevated readings is identified and cause is determined, the joint NASA and SpaceX teams will determine and announce a new target launch date," NASA stated, as cited by Space News.
Dragon Mission is Set to Deliver Supplies and Equipment to ISS
More than two tons of supplies and equipment will be delivered by the Dragon to the ISS.
As highlighted in a NASA briefing on June 2, the cargo on the mission include an "Earth science instrument that will study mineral dust in the atmosphere, experiments to study how sutured wounds heal in microgravity and aging of the immune system, and a student-developed experiment that will use biopolymers to create bricks from materials like those found in lunar and Martian regolith," according to Space News.
In recent weeks, the problem on the thruster is already the second issue that involves a Dragon spacecraft. On May 24, NASA said that the heat shield structure for the next Crew Dragon spacecraft was being replaced by SpaceX. This will launch in September on the Crew-5 mission.
Earlier in May, the heat shield failed an acceptance test. NASA revealed the heat shield issue in a statement. However, a published report denied that "there had been a leak of hypergolic propellants during the reentry of the Crew Dragon spacecraft that flew the Ax-1 private astronaut mission in April, damaging the heat shield," according to Space News.
"The data associated with Dragon's recent crew reentries was normal - the system performed as designed without dispute. There has not been a hypergolic leak during the return of a crewed Dragon mission nor any contamination with the heat shield causing excessive wear," NASA said in a statement.
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