CRS-20 launch
A SpaceX Falcon 9 lifts off at 11:50 p.m. Eastern March 6 carrying the last of the first generation of Dragon cargo spacecraft. Credit: SpaceX webcast

WASHINGTON — A SpaceX Falcon 9 lifted off March 6 and placed into orbit a Dragon spacecraft on the final flight of that version of the cargo vehicle.

The Falcon 9 launched from Space Launch Complex 40 at Cape Canaveral Air Force Station at 11:50 p.m. Eastern. The Dragon spacecraft separated from the rocket’s upper stage in low Earth orbit nine and half minutes later.

That Dragon spacecraft, on a mission called CRS-20, will arrive at the International Space Station at about 7 a.m. Eastern March 9. The spacecraft is carrying 1,977 kilograms of cargo for the station, including science experiments and crew supplies.

Among the payloads on the Dragon is Bartolomeo, an external experiment platform developed by Airbus that will be installed on the station’s Columbus module. Bartolomeo will be operated by Airbus as a commercial platform in cooperation with the European Space Agency.

Dragon will remain at the station for about one month before departing with more than 1,680 kilograms of cargo for return to Earth. The exact date of the return will depend on weather conditions and the completion of scientific investigations that will be brought back to Earth, said Joel Montalbano, deputy manager for International Space Station program, during a pre-launch briefing March 6 at the Kennedy Space Center.

When Dragon does return home, it will mark the end of SpaceX’s original Commercial Resupply Services (CRS) contract with NASA. That contract, awarded in December 2008, originally included 12 flights for $1.6 billion. NASA added eight missions to the contract, which had a maximum value of $3.1 billion.

SpaceX won one of three CRS-2 contracts in January 2016, along with Orbital ATK (now Northrop Grumman) and Sierra Nevada Corporation, to continue cargo deliveries to the station. The first of those missions for SpaceX, called CRS-21, is scheduled to launch in the fall.

Those future SpaceX CRS missions will use a version of the Crew Dragon spacecraft that SpaceX is developing for NASA’s commercial crew program. That version lacks the SuperDraco thrusters in Crew Dragon’s launch abort system and has a smaller life support system, said Hans Koenigsmann, vice president of build and flight reliability at SpaceX, during the pre-launch briefing. The spacecraft will have about 20% more volume than the current cargo Dragon.

The new Dragon will also be designed for greater reuse. While the spacecraft flying the CRS-20 mission is making its third flight, a milestone two other Dragon spacecraft have reached, Koenigsmann said the new cargo Dragon is designed for five flights.

The actual number of flights the spacecraft can make remains to be seen, he acknowledged. “The number of flights right now is a design number. A lot of that depends on what you see when you come back,” he said. “In reality, we might be able to run the capsule six times, or four times, depending on what we find.”

The launch set another milestone for the company with the 50th successful booster landing. The Falcon 9 first stage landed eight and a half minutes after liftoff at Landing Zone 1 at Cape Canaveral. The stage was making its second flight, having previously launched the CRS-19 Dragon mission in December 2019.

The company had hoped to hit that milestone on the previous launch Feb. 17, carrying a batch of 60 Starlink satellites. However, the stage failed to land on the droneship in the Atlantic, instead hitting the ocean nearby.

Koenigsmann said at the briefing that the stage didn’t suffer a technical problem that caused the failed landing, but rather diverted to avoid hitting the ship. “It did that primarily because the winds it encountered were not the winds that were predicted,” he said, because models didn’t accurately predict a change in winds around the landing time.

This landing faced challenges of its own because of gusty low-level winds that threatened to exceed launch limits. “Rocket will land in highest winds ever at Cape Canaveral tonight,” tweeted Elon Musk, chief executive of SpaceX, two and a half hours before the landing. “This is intentional envelope expansion.”

The booster, though, landed safely on a pad at Landing Zone 1. “Envelope expanded,” Musk tweeted minutes later.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...