CRS-16 Falcon 9 first stage makes unplanned water landing

Michael Cole

CAPE CANAVERAL, Fla. — After 26 straight successful landings of its Falcon 9 booster, SpaceX experienced a landing failure amidst an otherwise successful launch to orbit of the CRS-16 cargo resupply mission to the International Space Station (ISS).

The mission launched from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station at 1:16 p.m. (18:16 GMT) on Dec. 5, 2018. Following successful first stage separation at 2 minutes and 26 seconds into the flight and a successful boostback burn that began 13 seconds later, the return of the new Falcon 9 booster to a planned landing at SpaceX Landing Zone 1 began to go awry.

During re-entry and landing burns that began around 6 minutes and 8 minutes respectively into the flight, one or more of the booster’s grid fin hydraulic pumps stalled, sending the plummeting rocket off course from its planned landing site.

“It actually targets a landing point in the water as it loses control,” said Hans Koenigsmann, vice president of Build and Flight Reliability at SpaceX, as he narrated an onboard camera video of the rocket’s descent in a post-launch press conference. “So, in other words it is trying to stay away from land. Trying to stay safe.”

As it continued to descend, the rocket is seen in video to begin to spin like a slowly twirling pencil in a counterclockwise motion, the Merlin engine’s beneath it fighting to stabilize its flight.

The descent carried the Falcon 9 to an area off the coast from the landing zone where it seemed to gently settle and momentarily hover just above the surface of the waves, before finally pitching over and splashing into the water.

“It’s really amazing how it stopped rotating at the very end as the landing legs come out,” Koenigsmann said. “…it just lands on the water.Then it sinks in and falls over. And continues to work.”

SpaceX continued to receive data from the booster even as it tossed in the waves after the unexpected soggy landing.

The Falcon 9 booster splashed into the water some 2 miles (3 km) off the coast from the SpaceX landing zone.

“There was some malfunction with the grid fins,” Koenigsmann said, but refrained from speculating further as to the causes of the landing anomaly. “The important part here is that we have a safety function on board that makes sure the vehicle does not go on land. That worked perfectly. It avoids land. And if it is on land it avoids buildings. It is very smart that way. So it stays away from populations and property, and ensures public safety.”

The rest of the CRS-16 launch proceeded perfectly, with the Dragon spacecraft entering successful orbit, deploying its solar arrays, and beginning its chase of the ISS. The Dragon spacecraft is scheduled to arrive at the ISS around 6 a.m. EST (11:00 GMT) on Saturday, Dec. 8, 2018.

“We’re preparing a tow so we can get it safely into the harbor and recover it,” Koenigsmann said.