Rocket Lab catches a booster falling from space with a helicopter
Catch a falling rocket and bring it back to shore…
On Tuesday (Monday night in New York), Rocket Lab, a small company with a small rocket, pulled off the first half of that feat on its latest launch from the east coast of New Zealand.
After sending a payload of 34 small satellites into orbit, the company used a helicopter to catch the spent 39-foot-long booster stage of the rocket before it crashed into the Pacific Ocean.
In the future, Rocket Lab hopes to refurbish a salvaged booster and then use it for another orbital mission, a feat so far only achieved by one company: Elon Musk’s SpaceX.
A video feed from the helicopter showed a long cable hanging from the plane with cloudy skies below. Then the propellant appeared suspended under the parachute.
“Here we go, we’ve got a first look at it,” said commentator Murielle Baker on the Rocket Lab show. The grappling hook at the end of the helicopter cable snagged the parachute line before the captured thruster swung out of view of the camera.
Cheering from Rocket Lab Mission Control initially confirmed a successful take.
However, the company later provided an update that qualified the success. Peter Beck, the general manager of Rocket Lab, said on Twitter that the helicopter pilots reported that the thruster was not suspended under the helicopter quite the same way as during testing and that they dropped it in the ocean, where it was picked up by a Rocket Lab ship.
Eventually, Rocket Lab would like the helicopter to carry a taken booster to dry land and avoid salt water damage that makes reusing a booster difficult and possibly impractical.
Rocket Lab gives most of its missions fancy names. This one was called “There and Back Again,” a nod to the encore recovery as well as the subtitle of JRR Tolkien’s novel “The Hobbit.” Director Peter Jackson’s Hobbit film trilogy was filmed in New Zealand.
Rocket Lab’s Booster Socket is the latest advancement in an industry where rockets were once expensive single-use disposable items. Reusing all or part of an element reduces the cost of delivering payloads to space and could speed up the launch rate by reducing the number of rockets to be manufactured.
“Eighty percent of the cost of the entire rocket is in this first stage, both in terms of materials and labor,” Rocket Lab chief executive Peter Beck said Friday.
SpaceX pioneered a new era in reusable rockets and now regularly lands the first stages of its Falcon 9 rockets and flies them again and again. Falcon 9 second stages (as well as Rocket Lab’s Electron rocket) are always thrown away, usually burning up as they re-enter Earth’s atmosphere. SpaceX is designing its next-generation super rocket, Starship, to be fully reusable. Competitors like Blue Origin and United Launch Alliance, as well as Chinese companies, are also developing rockets that would be at least partially reusable.
NASA’s space shuttles were also partially reusable, but required extensive and expensive work after each flight, and they never lived up to their promise of airliner-like operations.
For the Falcon 9, the booster fires multiple times after it separates from the second stages, slowing it en route to a smooth landing on a floating platform in the ocean or on land. The Electron is a much smaller rocket, which makes it more difficult to reuse.
“You have to spend every bit of your thruster just to launch missions,” Beck said. This ruled out the possibility of propulsive landings like Falcon 9 boosters.
Instead, Rocket Lab engineers came up with a more fuel-efficient approach, adding a system of thrusters that expel cold gas to steer the thruster as it falls, and thermal shielding to protect it from temperatures exceeding 4 300 degrees Fahrenheit.
The booster separated from the second stage at an altitude of about 50 miles, and during descent accelerated to 5,200 miles per hour.
“If we came in flat, for example, on its side, the rocket would just burn out,” Beck said. “So we have to orient and control that first stage so that the heat shield and the motors are off for the entire flight profile.”
The friction of the atmosphere acted as a brake. About 7 minutes and 40 seconds after liftoff, the thruster’s sink rate slowed to less than twice the speed of sound. At this point, a small parachute called the drug deployed, adding additional drag. A larger main parachute further slowed the rappel to a more leisurely pace.
Rocket Lab had demonstrated in three previous launches that Electron boosters could survive re-entry. But on those missions, the boosters splashed down in the ocean and were later pulled out for examination.
This time, a Sikorsky S-92 helicopter hovering in the area encountered the thruster in flight, pulling a cable with a grappling hook through the line between the drug and the main parachutes.
With almost all of its propellant expended, the propellant was much lighter than at launch. But it was still a heavy piece of metal – a cylinder four feet in diameter and about as tall as a four-story building and weighing almost 2,200 pounds or one metric ton.
Mr. Beck said Rocket Lab would eventually like to nab boosters for about half of its missions. The added weight of thrusters, parachutes, and thermal protection reduces the 550-pound payload by 10-15 percent.
Later this month, Rocket Lab could launch CAPSTONE, a NASA-funded but privately operated mission that will study a highly elliptical trajectory around the moon for use by a future US lunar space station. Before the end of this year, Rocket Lab hopes to start using a second launch site on Wallops Island in Virginia.