Pick up a downed rocket and take it back to the shore…
On Tuesday (Monday evening in New York), Rocket Lab, a small company with a small rocket, accomplished the first half of this feat during its latest launch from New Zealand’s east coast.
After sending a payload of 34 small satellites into orbit, the company used a helicopter to catch the booster stage used for the 39-foot-long rocket before it splashed down into the Pacific Ocean.
In the future, Rocket Lab hopes to replenish a recovered booster and then use it on another orbital mission, a feat only one company has achieved so far: Elon Musk’s SpaceX.
A video stream from the helicopter showed a long wire hanging from the plane with an overcast sky below. Then the booster appeared dangling under the canopy.
“Here we are, we have our first glimpse of it,” said Muriel Baker, commentator during the Rocket Lab broadcast. A tangled hook at the end of the helicopter cable caused the parachute line to malfunction before the captured booster swung out of the camera view.
Initially, cheers from the Rocket Lab mission control center confirmed its success.
However, the company later provided an update that qualified for success. Peter Beck, chief executive of Rocket Lab, said on Twitter that helicopter pilots reported that the booster was not hanging below the helicopter quite as it is during pilot tests and that they let it go into the ocean, where it was retrieved by the Rocket Lab ship.
Ultimately, Rocket Lab wants the helicopter to carry a hunted booster all the way back to Earth and prevent saltwater damage that makes reusing the booster difficult and possibly impractical.
Rocket Lab gives most of its tasks eccentric names. This was called “There and Back Again”, a nod to the restoration of the augmenter as well as the subtitle of J.R.R. Tolkien’s novel “The Hobbit”. The Hobbit trilogy, directed by Peter Jackson, was filmed in New Zealand.
Rocket Lab’s Enhanced Hunting is the latest advance in an industry where rockets have been too expensive for single use. Reusing all or part of one lowers the cost of transporting payloads into space and can speed up the launch pace by reducing the number of rockets that need to be built.
“Eighty percent of the cost of the entire rocket in that first stage, in terms of materials and labor,” said Peter Beck, chief executive of Rocket Lab, in an interview Friday.
SpaceX pioneered a new era of reusable rockets, and now it regularly lands and flies the first stages of its Falcon 9 rockets again and again. Falcon 9’s second stages (as well as Rocket Lab’s Electron rocket) are still neglected, and usually burn up while re-entering Earth’s atmosphere. SpaceX is designing its next-generation super rocket, the Starship, to be completely reusable. Competitors such as Blue Origin, United Launch Alliance, and companies in China are developing missiles that can be at least partially reused.
NASA’s space shuttles were partially reusable, but required labor-intensive and expensive work after each flight, and did not deliver on their promises of aircraft-like operations.
For the Falcon 9, the booster rocket is fired several times after it separates from the second stages, slowing it down on its way to a quiet location either on a floating platform in the ocean or a location on land. The electron is a much smaller rocket, which makes it more difficult to reuse.
“You have to spend every bit of your fuel just to get the tasks done,” Mr. Beck said. That ruled out the possibility of thrust landings like the 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 guide the booster as it falls, and thermal protection to protect it from temperatures in excess of 4,300 degrees Fahrenheit.
The booster detached from the second stage at an altitude of about 50 miles, and during the descent, it accelerated to 5,200 mph.
“If we get to an apartment, say, on the side, the missile will burn out,” said Mr. Beck. “So we have to direct and control that first stage to turn off the heat shield and actuators through the entire flight profile.”
Atmospheric friction acted as a brake. About 7 minutes, 40 seconds after takeoff, the fall speed of the booster slowed to less than twice the speed of sound. At that point, a small parachute called a drogue was deployed, which added extra traction. The larger main canopy slowed the booster to a more comfortable rate.
Rocket Lab has shown in three previous launches that electron boosters can survive again. But on those missions, the boosters were scattered in the ocean and then pulled out for inspection.
This time, a hovering Sikorsky S-92 helicopter met the air booster, pulling a hook cable grappling across the line between the rotating parachutes and main parachutes.
With nearly all the fuel exhausted, the booster was much lighter than it was at launch. But it was still a heavy piece of metal—a cylinder four feet in diameter and the length of a four-story building and weighed nearly 2,200 pounds, or a metric ton.
Mr. Beck eventually said that Rocket Lab would like reinforcements for about half of its missions. The added weight of thrusters, parachutes and thermal protection reduces the 550-pound payload by 10 to 15 percent.
later this month, Rocket Lab can 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 begin using its second launch site on Wallops Island, Virginia.