WASHINGTON — SpaceX launched a Dragon spacecraft to the International Space Station April 21 whose cargo includes more crew supplies and fewer science experiments than usual.
A Falcon 9 lifted off at 4:15 a.m. Eastern from Launch Complex 39A at the Kennedy Space Center, deploying the SpX-32 cargo spacecraft into low Earth orbit nearly 10 minutes later. The Dragon is scheduled to dock with the station at about 8:20 a.m. Eastern April 22.
The Dragon is carrying 3,021 kilograms of cargo to the station. Unlike other recent Dragon cargo missions, SpX-32 is carrying far more crew supplies: 1,468 kilograms, compared to 961 kilograms on the SpX-31 mission last November and 545 kilograms on SpX-30 in March 2024.
NASA announced in March it would add more crew supplies, like food, to SpX-32 because of concerns that a Cygnus cargo spacecraft that was to fly the NG-22 cargo mission in June may have suffered damage during shipment to the launch site. NASA and Northrop Grumman scrapped that mission in late March after confirming the spacecraft’s pressurized cargo module was damaged.
The additional crew supplies on SpX-32 comes at the expense of science. While SpX-30 flew 1,135 kilograms of science investigations as part of its pressurized cargo and SpX-31 917 kilograms, SpX-32 has only 255 kilograms of science inside the Dragon.
At a prelaunch briefing for SpX-32 April 18, NASA officials were unable to say how many science investigations originally planned to fly on this mission were removed to make room for additional supplies. “It is a continuous process as we’re working with our cargo team,” said Jennifer Buchli, NASA chief scientist for the ISS program.
NASA later told SpaceNews that 14 science investigations were removed from SpX-32. “Resupply flight manifests are dynamic leading up to the final close out as NASA continuously looks for efficiencies to maximize cargo space,” the agency said in a statement. “As more space becomes available, more science is added to the manifest.”
Buchli said that more than 30 science payloads are flying on SpX-32, and those that were bumped from the flight will be remanifested on later cargo flights or possibly the Crew-11 mission launching to the station this summer.
The science that is going to the station on SpX-32 includes plant growth experiments, an aerosol monitor to study air inside the station and pharmaceutical payloads. The spacecraft is also delivering 755 kilograms of unpressurized cargo in the trunk section: the European Space Agency’s Atomic Clock Ensemble in Space (ACES) experiment to study general relativity and the Space Test Program – Houston 10 suite of experiments.
NASA said at the prelaunch briefing there were no concerns about the level of food and other consumables on the station. “Right now the crew remains well supplied,” said Zebulon Scoville, deputy manager of the NASA ISS Transportation Integration Office. That includes margin should the next cargo mission, SpX-33, slip from its planned launch late this summer.
By the fall, any squeeze on cargo resupply to the station should ease. Scoville said the Cygnus NG-23 mission is scheduled for launch in mid-September, with the first flight of Japan’s HTV-X, an upgraded version of the HTV cargo vehicle, expected to fly later in the fall.
Sierra Space’s Dream Chaser may also make its first flight to the station before the end of the year after extensive delays. “We’re still trying to assess the exact timing,” he said, “and the mission objectives that they’re going to be able to accomplish.”
The schedule of those upcoming cargo missions will also depend on the availability of docking and berthing ports on the station. “The traffic pattern is full,” Scoville said.
