The SpaceX CRS-22 mission has come to a close, with Cargo Dragon having departed the International Space Station on Thursday, July 8 after a series of weather delays. NASA and SpaceX teams continued to monitor weather at the landing zones ahead of a successful undocking at 10:45 AM EDT (14:45 UTC).
Splashdown occurred Friday evening at 11:29 PM EDT (03:29 UTC), in a landing zone off the coast of Tallahassee, Florida, in the Gulf of Mexico.
The mission began with liftoff from historic LC-39A at NASA’s Kennedy Space Center in Florida on June 3. Two days later, the spacecraft successfully performed an autonomous docking to IDA-3 on the zenith (upward facing) docking port of the Harmony module.
This docking port is preferred for Cargo Dragon missions over IDA-2 on the forward port so that the station’s robotic arm can access unpressurized cargo in Dragon’s trunk. IDA-2 and IDA-3 are the only docking ports compatible with the SpaceX Dragon 2 and Boeing Starliner spacecraft, both of which dock to the station without the assistance of Candarm2.
The Northrop Grumman Cygnus cargo vehicle and Japan’s HTV and upcoming HTV-X vehicles berth to the station with the help of the robotic arm, using nadir (Earth-facing) ports on the station’s Unity or Harmony modules. Russian Soyuz and Progress vehicles autonomously dock to the Russian segment of the ISS.
The Dragon spacecraft operating the CRS-22 mission is Dragon C209, making its first flight. Unlike the Crew Dragon vehicles, which are named by their first crews, Cargo Dragon 2 spacecraft are referred to by their serial numbers.
Dragon C209, while on its first flight, is sporting a reused heat shield which previously protected NASA astronauts Bob Behnken and Doug Hurley on the Demo-2 mission in August 2020. C209 is the second in a planned fleet of three Cargo Dragon 2 spacecraft.
CRS-22 is the second SpaceX cargo resupply mission under the CRS2 (Commercial Resupply Services 2) contract, and thus the second flight of the Cargo Dragon 2 spacecraft following the retirement of Cargo Dragon 1 after CRS-20. CRS-22 is also the sixth orbital Dragon 2 mission, including the uncrewed Demo-1 flight and three crewed flights to the ISS to date.
The CRS-22 mission delivered supplies and science investigations to the station, notably including the first two of six new solar arrays. The ISS Roll Out Solar Arrays (iROSAs) are being installed to improve power generation capabilities as the eight original solar array wings, installed between 2000 and 2009, are naturally beginning to degrade and produce less power. This coupled with the increasing science demands on the outpost necessitated adding six new, smaller arrays contracted through Boeing.
The first pair of solar arrays were installed over the course of three spacewalks conducted by ESA astronaut Thomas Pesquet and NASA astronaut Shane Kimbrough. The two remaining pairs of arrays will be launched on the SpaceX CRS-25 and CRS-26 missions.
Dragon also delivered a few CubeSats to be deployed from the ISS along with other pressurized cargo for NASA and ESA.
The Dragon spacecraft undocked at 10:45 AM EDT (14:45 UTC) on Thursday, July 8. This is a two day delay from the original undocking target of July 6 as a result of Tropical Storm/Hurricane Elsa causing weather concerns at the splashdown zones.
NASA and SpaceX teams continued to monitor weather conditions in advance of selecting the Tallahassee splashdown zone just prior to undocking. If weather or any other factors would have required an aborted landing after undocking, Dragon is capable of free flying for a couple days to await better landing conditions.
Once autonomous undocking is commanded, the spacecraft is monitored by ground controllers at SpaceX mission control (MCC-X) at the company’s headquarters in Hawthorne, California, as well as NASA controllers at the Johnson Space Center in Houston, Texas (MCC-H). Dragon’s departure is also watched by Shane Kimbrough onboard station.
Once the spacecraft is separated from the ISS, Dragon uses its Draco thrusters to maneuver into an orbit which passes over the selected splashdown zone. There are seven areas available for Dragon 2 missions: four off the west coast of Florida in the Gulf of Mexico and three off the east coast of Florida in the Atlantic.
GO Searcher has her fast boats loaded up ahead of her mission to pick up the CRS-22 Cargo Dragon.
With Elsa out in the Gulf, NASA and SpaceX are currently planning an Atlantic splashdown around midnight Wed night.
Any delays could still push splashdown back over to the Gulf. pic.twitter.com/YHKMBizzEj
— Stephen Marr (@spacecoast_stve) July 5, 2021
The four Gulf recovery zones – Pensacola, Panama City, Tampa, and the selected Tallahassee zone – are supported by SpaceX Dragon recovery vessel GO Navigator, stationed in Tampa Bay. The three zones in the Atlantic – Cape Canaveral, Jacksonville, and Daytona Beach – would have been supported by GO Searcher, stationed in Port Canaveral.
Prior to the deorbit burn, the Dragon capsule separates from its trunk, which carries unpressurized cargo and the spacecraft’s solar panels. The trunk will naturally decay from low Earth orbit within the next couple years and burn up on reentry.
Dragon then utilizes the Draco thrusters positioned around the spacecraft’s docking port to perform the deorbit burn, slowing the spacecraft enough to fall out of orbit on target for the splashdown zone. Dragon’s nosecone is then closed at the conclusion of the burn to protect the docking port during entry and splashdown.
After the deorbit maneuver, the reused heat shield protected the capsule from the intense heating of reentry, dispelling almost all of the spacecraft’s energy as Earth’s atmosphere passively slowed the spacecraft.
Once Dragon slowed sufficiently for heating to subside and the spacecraft reached denser atmosphere, a pair of drogue parachutes deployed to slow the vehicle further, followed by four main parachutes to slow the spacecraft to a safe splashdown velocity.
Splashdown occurred approximately 11:29 PM EDT on Friday, July 9 (03:29 UTC on Saturday, July 10).
Following splashdown, recovery teams safe the vehicle and pull the capsule on board the recovery vessel. A helicopter will be used to rush time sensitive return cargo from the recovery ship to the Kennedy Space Center, while all other cargo will be offloaded once the ship and Dragon return to Port Canaveral.
A total of 3,000 kilograms of return payload mass, including experiment samples in the capsule and empty iROSA Flight Support Equipment (FSE) in the trunk for a destructive reentry, are departing the station on board Dragon. Cargo Dragon 2 is the only active cargo vehicle capable of returning payloads from the ISS back to Earth, complementing the minimal cargo space available on returning crew vehicles.
Hardware being returned within Dragon’s capsule includes a developmental environmental control and life support system (ECLSS) unit, named the Catalytic Reactor Developmental Test Objective, which is being returned for troubleshooting, repair, and re-flight, as well as a Urine Processing Assembly (UPA) Distillation Assembly unit.
Also returning to Earth is a Sabatier Main Controller water production unit, and a set of Rodent Research Habitats which will be refurbished for future ISS experiments. In addition, an assembly of empty Nitrogen/Oxygen Recharge System (NORS) gas tanks are returning to be prepared for re-flight.
(Lead photo of Dragon CRS-22 during docking – via NASA)