SpaceX returns to flight with weekend Falcon 9 triple header
SpaceX successfully launched three Falcon 9 rockets in rapid-fire fashion over the weekend, putting 67 Starlink satellites into orbit within three days of winning approval from the Federal Aviation Administration to resume launchings in the wake of a rare in-flight failure on July 11.
SpaceX kicked off its return to flight by firing off 23 Starlink internet satellites from the Kennedy Space Center early Saturday, followed by a second Starlink launch from the Cape Canaveral Space Force Station early Sunday that put another 23 broadband relay stations into orbit. The third Falcon 9 was launched a few hours later from Vandenberg Space Force Base in California.
All three flights appeared to go off without a hitch.
NASA is counting on Falcon 9s to launch a Northrop Grumman Cygnus supply ship to the International Space Station on Aug. 3, followed by a SpaceX Crew Dragon flight to carry three agency astronauts and a Russian cosmonaut to the lab around Aug. 18.
The second stage slated for use with the piloted flight, known as Crew 9, will be test-fired in the coming days at a SpaceX facility near McGregor, Texas, to verify the company's corrective action will have no unexpected consequences.
"It's going to undergo a second stage hot fire around the 30th of July, and that's really to check out some of the new modifications that vehicle will have as a result of the anomaly," Steve Stich, manager of NASA's Commercial Crew Program, said Friday.
"We have been following along step-by-step with that investigation that the FAA has been doing, SpaceX has been very transparent, we've had our teams embedded in the investigation and following along all the changes on that booster."
The space agency has not yet formally cleared those flights for launch, but SpaceX's successful return to flight this weekend will no doubt play a role in the eventual decision.
Boeing engineers also had a busy weekend, successfully test-firing 27 maneuvering thrusters in the company's Starliner capsule now docked at the International Space Station.
The tests verified good performance with reaction control system -- RCS -- thrusters that ran into problems earlier and confirmed that known helium leaks in the capsule's propulsion system had remained stable and had not worsened.
The tests suggest the thrusters will work properly during the ship's eventual return to Earth.
"The one-pulse firings were designed to confirm the performance of each thruster," Boeing wrote in an update. "Between each firing, the team reviewed real-time data and all thrusters performed at peak thrust rating values.
"The helium system also remained stable," the company said. "Additionally, an RCS oxidizer isolation valve that was not fully seated previously was cycled several times during (Saturday's) testing and is now operating normally."
Launched June 5 on the spacecraft's first piloted test flight, the Starliner's crew -- commander Barry "Butch" Wilmore and co-pilot Sunita Williams -- originally expected to spend about eight days in space.
The mission has now lasted nearly two months because of work to troubleshoot the thruster issues and five helium leaks, one detected before launch and four that developed during the capsule's rendezvous with the space station.
NASA is expected to hold a major review late this week to assess the test data and to determine the ship's readiness to bring Wilmore and Williams safely back to Earth.
As for SpaceX and the Falcon 9, the company blamed the July 11 failure on a crack in an upper stage sensor line, caused by a loose bracket and metal fatigue, that led to a liquid oxygen leak.
The leak, in turn, led to extremely low temperatures in the engine's plumbing, slowing the flow of a fluid needed to restart the powerplant for a planned second "burn."
Instead, the engine suffered a "hard start" that damaged multiple components, preventing the rocket from reaching the planned orbit. While the stage remained intact, the Starlinks it carried to space were released in a much lower-than-planned orbit and subsequently burned up in the atmosphere.
Sarah Walker, a senior manager at SpaceX, said Friday that the "sense line" was not needed and would simply be removed from downstream rockets. She said the data it provided was available from other telemetry sources on the rocket.
As for piloted Crew Dragon flights, she added, the second stage engine only fires once and the leak that derailed the Starlink launch would not have been a factor in a crewed flight. In any case, the fitting that leaked will be removed.
"I'm extremely confident in the team, the integrated approach in which NASA has been incorporated into the response," said Nick Hague, Crew 9 co-pilot and veteran of a Russian Soyuz launch abort. "And I'm excited to strap on to the rocket when the team decides it's time to go."
He said the crew was training at SpaceX's Hawthorne, Calif., headquarters the day after the Starlink launch anomaly occurred "and from the get-go they brought us into the conversation and told us everything that they knew."
The Federal Aviation Administration, which is responsible for licensing U.S. launches, agreed with the SpaceX failure analysis, concluding "no public safety issues were involved."
"This public safety determination means the Falcon 9 vehicle may return to flight operations while the overall investigation remains open, provided all other license requirements are met," the FAA said in a statement.
Along with providing an update on SpaceX's near-term Falcon 9 plans, Walker also addressed an unexpected issue with debris from Crew Dragon trunk sections that managed to survive the heat of re-entry to hit the ground.
The trunk section, outfitted with solar cells, helps power the Crew Dragon in space and carries external station payloads to orbit in an unpressurized environment.
Before re-entry, the trunk is jettisoned. The crew capsule, equipped with a heat shield, then fires its braking rockets to drop out of orbit for a precisely-targeted ocean splashdown. The trunk continues on in a low orbit and eventually makes an uncontrolled re-entry.
Early in the program, engineers concluded the entire trunk would completely burn up during re-entry. But on several occasions, relatively large, charred chunks of trunk debris have survived entry to hit the ground.
Returning Crew Dragon astronauts and recently launched cargo Dragon supply ships have all returned to splashdowns off the coast of Florida, either in the Gulf of Mexico or the Atlantic Ocean.
Walker said SpaceX now plans to move all cargo and Crew Dragon splashdowns to the Pacific Ocean off the West Coast. Trunk sections now will be jettisoned after the deorbit rocket firing, making sure they fall back into the atmosphere in roughly the same area the crew and cargo capsules do, that is, well offshore.