Dragon Endeavour’s historic mission draws to a close

by Tobias Corbett

Just over two months after it became the first American spacecraft to launch astronauts into space in nearly a decade, SpaceX’s Crew Dragon Endeavour is nearing the end of its historic flight in space.

The vehicle and its two astronaut crew are departed from the International Space Station (ISS) on 1 August at 7:34 pm EDT (23:34 UTC) ahead of splashdown in the Gulf of Mexico on Sunday off the coast of Pensacola, Florida.

This will mark the first splashdown carried out by a crewed American spacecraft and the first world-wide planned at sea landing of a crew mission since the Apollo-Soyuz Test Project mission in July 1975.

The Soyuz 23 mission in October 1976 accidentally landed in Lake Tengiz in the middle of blizzard.

For splashdown, this will mark the third time a Crew Dragon spacecraft has landed in the sea, following SpaceX’s Demo-1 and In-Flight Abort test missions — both of which occurred without crew.

Endeavour launched into space from Launch Complex 39A at the Kennedy Space Center in Florida on 30 May 2020 carrying NASA astronauts Doug Hurley and Robert “Bob” Behnken as part of Demo-2, the first crewed test flight of SpaceX’s Crew Dragon vehicle.

The launch also marked the first crewed orbital spaceflight from U.S. soil since STS-135, the final flight of the Space Shuttle Program in 2011.

Crew Dragon Capsule C204 being recovered after splashdown following Demo-1. (Credit: NASA)

The spacecraft docked to the International Docking Adaptor 2 located on Pressurized Mating Adaptor 2 on the forward end of the Harmony module of the International Space Station just 19 hours after liftoff, joining the then three person Expedition 63 crew aboard the orbiting laboratory.

Bob and Doug’s mission was originally to last around a week but was extended to over 60 days in order to bolster activity aboard the Station during a period of low crew operations which started in April 2020 with the undocking of Soyuz MS-13 and the end of Expedition 61.

Years prior, NASA agreed to stop purchasing enough seats on the Russian Soyuz at the end of 2019 that Soyuz crew missions to Station would reduce from four to two per year — with those eliminated two flights being flown instead by the Commercial Crew vehicles of Dragon and Starliner.

Delays to the Commercial Crew Program’s first crewed flight and only two crewed Soyuz missions to the Station in 2020 necessitated a crew reduction from six to three beginning in April 2020.

Demo-2 then launched one month later, bringing the Station’s crew compliment to five and enabling the resumption of most scientific work on the outpost that had been stopped due to the lack of crew.

During their time aboard the Station, Bob and Doug took part in scientific experiments and maintenance of the ISS, including four spacewalks which were carried out by Behnken and Expedition 63 Commander Christopher Cassidy.

Prior to undocking, NASA and SpaceX held a meeting to jointly decide on the weather outlook in the landing zone off the coast of Pensacola, Florida.  The forecast was a primary driver on whether or not to press ahead with undocking and return to Earth.

That meeting resulted in a “go” decision; Bob and Doug then proceeded to re-enter their vehicle and begin preparations for departure.

At 5:45 pm EDT (21:45 UTC), the two waved goodbye to Cassidy, Anatoli Ivanishin, and Ivan Vagner before closing the hatches that separate Endeavour and the Station.

At 7:34 pm EDT (23:34 UTC), Endeavour autonomously opened the hooks on its International Docking System Standard (IDSS) docking ring, which will terminate the link between the Crew Dragon and Station.

Less than ten minutes later, at 7:40 pm EDT (21:40 UTC), the spacecraft performed the first of three departure burns, firing its Draco thrusters in order to separate itself from the ISS.

Between 8:25 pm and 9:15 pm EDT (00:25 to 01:15 UTC on 2 August), Dragon performed two more of these burns, each time pushing it further and further away from the laboratory it, and its crew, have called home for the past two months.

From here, Endeavour is scheduled to remain in free flight for over twelve hours, following which — weather permitting –Bob, Doug, and Endeavour will begin their final preparations for their return to Earth.

The latest path and intensity forecast for Hurriance Isaias — predicted to be passing just offshore or over Cape Canaveral near Dragon’s planned landing time Sunday, 2 August. (Credit: National Hurricane Center/National Oceanic and Atmospheric Administration)

Six-hours before Dragon Endeavour ends its first flight, NASA and SpaceX will hold one final joint meeting where they will reaffirm their prime landing site.  NASA has seven possible landing sites off the Coast of Florida.

Although seven sites exists, all three located off Florida’s eastern coast are unavailable due to Hurricane Isaias, which will be passing very close to the eastern coast of the state.

No concrete decision will be made until NASA and SpaceX’s joint meeting six hours before splashdown, although as of now the prime landing site is Pensacola located off the coast of the Florida panhandle.

If all goes to schedule, Bob, Doug, and Endeavour will splashdown off the coast of Pensacola, Florida, at 2:41 pm EDT (18:41 UTC) on 2 August 2020.

Upon splashdown, SpaceX recovery forces will converge on the capsule, connect it to tow and lift lines, and bring it aboard GO Searcher.  There, the crew will emerge from the capsule and receive all necessary medical test and checkouts.

NASA and SpaceX will aim for no more than 60 minutes from splashdown to crew egress of Dragon.

After medical checkouts, Bob and Doug will be airlifted by helicopter to Pensacola, where they will board a waiting NASA aircraft and be flown back to Ellington field in Houston, Texas.

Dragon Endeavour will then be brought back to the Cape Canaveral Air Force Station, Florida, where engineers and technicians will thoroughly inspect the craft before refurbishing it for its next mission, Crew-2, in Spring 2021.

The Crew-2 mission will also feature a previously-flown Falcon 9 first stage, the same one to be used in late-September 2020 to launch the Crew-1 mission to the Station.

Related Articles