After almost 64 days in space, “Bob and Doug’s Excellent Adventure” ended in fine style on Sunday afternoon, as Dragon Endeavour made a smooth 2:48 p.m. EDT splashdown in the Gulf of Mexico, off the coast of Pensacola, Fla. Demo-2 crewmen Doug Hurley and Bob Behnken, who launched last 30 May, spent a total of 62 days aboard the International Space Station (ISS), working alongside Expedition 63 Commander Chris Cassidy and his Russian crewmates Anatoli Ivanishin and Ivan Vagner. Whilst there, they supported dozens of research experiments, served as on-orbit plumbers, maintenance men and computer wizards and were instrumental in completing four sessions of Extravehicular Activity (EVA) to replace outdated nickel-hydrogen batteries in the station’s S-6 truss with smaller, lighter and more capable lithium-ion units.
Having undocked from the station at 7:35 p.m. EDT Saturday, Dragon Endeavour spent 19 additional hours in free flight, before executing a precise deorbit “burn”, a picture-perfect re-entry and an on-point landing in the calm-as-glass waters of the Gulf. In doing so, Hurley and Behnken became the first U.S. astronauts to return to an oceanic splashdown since the traumatic end of the Apollo-Soyuz Test Project (ASTP) on 24 July 1975. This also marked the first occasion that a crew of astronauts had ever returned from orbit aboard a commercially-owned vehicle.
In spite of lingering concerns about Hurricane Isaias as it continues to batter the Bahamas and head for the United States’ eastern seaboard, NASA and SpaceX decided early Saturday morning to push for an on-time splashdown on Sunday afternoon. Seven potential locations off the Florida coast—three to the east, four to the west—had been identified, with Pensacola ultimately selected as the primary splashdown point and Panama City held in reserve. And fears of an area of disturbed weather in the tropics ultimately proved unfounded as SpaceX’s recovery vessel, Go Navigator, put to sea at 9:20 a.m. EDT Sunday.
Meanwhile, the effort to bring Hurley and Behnken home began in earnest on Saturday morning, when they bade a fond farewell to Cassidy, Ivanishin and Vagner. “All my bags are packed,” Behnken tweeted. “I’m ready to go.” Ever the pragmatic test pilot, Hurley—the Demo-2 mission commander—added: “Now it’s time to finish our DM-2 test flight in order to pave the way for future Dragon crews.” Hatches between the station’s International Docking Adapter (IDA)-2 and Dragon Endeavour were verified as closed at 5:36 p.m. EDT and the two spacecraft parted company on time at 7:35 p.m.
During the farewell ceremony, Cassidy poignantly handed over the U.S. flag which previously flew on the first shuttle mission, STS-1 in April 1981, and the last shuttle mission, STS-135 in July 2011. Interestingly, Hurley piloted STS-135 and was in the unique position to have dropped off and picked up this unique emblem of the United States. Cassidy noted the flag’s “deep history”, before passing it to Hurley, with the words: “Doug, the flag’s all yours!”
Two short pulses from the four hypergolic Draco thrusters on Dragon Endeavour’s forward bulkhead served to initially push them apart, before a series of four computer-commanded “departure burns” over the next 90 minutes increased the distance between the two spacecraft. “It’s been a great two months,” Hurley radioed Cassidy, “and we appreciate all you’ve done as a crew to help us prove out Dragon on its maiden flight.”
This was not the first time that Cassidy and Hurley had flown together; in fact, way back in July 2009, both men flew the first missions of their respective astronaut careers aboard shuttle Endeavour on STS-127. A few hours later, a six-minute-long “phasing burn” positioned Dragon Endeavour onto the proper orbital path to support its re-entry and target the splashdown point off the Pensacola coast. And on Sunday morning, Hurley and Behnken were awakened to a pre-recorded message from their sons, Jack and Theo.
This afternoon’s dramatic return to Earth got underway at 1:51 p.m. EDT, when Dragon Endeavour’s trunk was discarded. With its thermal control, power and avionics capabilities thus gone, Hurley and Behnken were reliant upon their ship’s on-board batteries for the last phase of their dramatic mission.
At 1:56 p.m., precisely on schedule, the lengthy de-orbit burn of the Draco thrusters got underway to commit them to a landing in the Gulf. The burn ran crisply for 11 minutes and 22 seconds and, shortly after an on-time shutdown, at 2:11 p.m. the ship’s nose cone was closed and locked for re-entry.
“Burn went great,” SpaceX Crew Operations and Resources Engineer (CORE) Mike Heiman told the astronauts. “Your vehicle is still looking really good for entry.”
“Okay, Dragon copies,” replied Hurley. “Thank you.”
Twenty minutes later, Dragon Endeavour passed “entry interface” as it encountered the uppermost traces of the sensible atmosphere and began to feel thermal extremes as high as 1,900 degrees Celsius (3,500 degrees Fahrenheit). Hurley and Behnken’s ride downhill was described by NASA as no higher than three times the force of terrestrial gravity, not dissimilar to what they experienced during liftoff and roughly akin to a mild ride on a rollercoaster. Passing through the worst of aerodynamic heating, the ship’s two drogue parachutes were deployed at an altitude of 18,000 feet (5,500 meters) and a velocity of 350 mph (560 km/h). NASA’s Brandi Dean reported that she clearly heard the sonic booms which signaled the return of America’s latest space heroes.
“Visual, two drogues out,” came the confirmation at 2:44 p.m. The drogues dramatically slowed Dragon Endeavour to about 119 mph (190 km/h). But still hearts remained in throats, until the drogues were detached and the four red-and-white canopies of Dragon Endeavour’s main parachute system were fully deployed. Then came the call that everyone had been waiting for. “We are visual on four chutes out” came the call at 2:45 p.m., as the four canopies unfolded beautifully and in unison.
Splashdown—the first by a U.S. piloted spacecraft in just over 45 years—came exactly on time at 2:48 p.m. And despite some ratty communications in the water, wind speeds of just 2.5 mph (4 km/h) were well within limits and Hurley and Behnken’s first view of home through Dragon Endeavour’s windows would be one of blue skies, fluffy white clouds and still-as-glass water on the Gulf of Mexico. Hurley confirmed their status in a “Stable One” orientation, comfortably upright in the water.
Immediately after splashdown, two fast boats could be seen rapidly approaching the blackened and scarred Dragon Endeavour, where they executed an initial “sniff test” to verify that no hazardous chemical or fumes were present. Shortly after 3 p.m., one of the boats’ crew ascended the nose of Dragon Endeavour to set up the rigging equipment which would allow the spacecraft to be hoisted from the water and onto the so-called “nest” atop the deck of the Go Navigator. This was completed soon after 3:30 p.m.
Hopes to extract the astronauts were slightly delayed, due to the possibility of lingering traces of nitrogen tetroxide and monomethyl hydrazine, and sampling was correspondingly undertaken. Hurley was asked to also take measurements inside the cabin, both of which produced negative results. Finally, at 3:59 p.m., a little over an hour since splashdown, the hatch was opened and the process of extracting first Behnken, then Hurley, got underway. Both men warmly thanked the NASA and SpaceX teams for their support.
The two astronauts are expected to next be helicoptered back to Pensacola, then flown by NASA aircraft to Ellington Field, near the Johnson Space Center (JSC) in Houston, Texas. There they will be reunited with their families and loved ones.
AmericaSpace’s full Demo-2 Mission Report will appear tomorrow.