Aiming for reusability, Rocket Lab has demonstrated the mid-air recovery of a booster test article in a key test before rigging the first stage of the company’s Electron launcher with a parachute on missions beginning later this year.
The company said the test in early March showed Rocket Lab’s concept of catching a descending Electron booster with a helicopter can work.
For the recovery test, Rocket Lab dropped a test article of an Electron rocket first stage from a helicopter over the ocean off the coast of New Zealand. A parachute deployed from the test article to slow its descent, then another helicopter swooped in to snag the parachute’s drogue line with a grappling hook on the end of a long boom, Rocket Lab said an April 8 statement.
The mid-air catch occurred at an altitude of around 5,000 feet (1,500 meters), according to Rocket Lab. The helicopter carried the inert booster back to land after catching it over the ocean.
The drop test occurred before New Zealand’s government introduced restrictions on business operations in response to the coronavirus pandemic.
Rocket Lab wants to recover and reuse the first stage from its Electron small satellite launcher to achieve a more rapid cadence of launches, limiting pressure on the company’s factories in Auckland, New Zealand, and Long Beach, California.
Launches of Rocket Lab’s Electron rocket take off from a private spaceport on New Zealand’s North Island. The company is also readying a launch pad at Wallops Island, Virginia, to support Electron flights beginning later this year.
Rocket Lab performed guided re-entry experiments on the first stage during the company’s two most recent launches, demonstrating the booster could survive a plunge back through the atmosphere after releasing the Electron’s second stage and satellite payloads to continue into orbit.
The Electron boosters on those missions — which occurred in December and January — carried guidance and navigation equipment, an independent S-band telemetry system, an on-board flight computer and sensors to gather data during the stage’s re-entry back into the atmosphere.
One of the stages was also equipped with control thrusters to flip the booster 180 degrees after stage separation, putting the rocket in the correct orientation for re-entry. The booster maintained its angle of attack throughout the descent, slowing from an initial velocity of more than 4,300 mph (7,000 kilometers per hour) to less than 560 mph (900 kilometers per hour) when it hit the ocean.
Beck said Rocket Lab will forego additional guided re-entry experiments on its next launches, while engineers focus on an upgrade to add a parachute to the first stage for missions later this year.
“We’ve really learned all we needed to learn,” Beck said in a recent interview with Spaceflight Now. “The stage performed perfectly (on the re-entry experiments), it guided itself all the way through the re-entry corridor and impacted in the ocean. We got data all the way to impact, and that was great.”
Eventually, Rocket Lab wants to catch a parachute-equipped rocket returning from space with a helicopter to prevent sensitive engine components and other hardware from being contaminated by salty sea water.
The drop test in early March showed that plan is feasible, Rocket Lab said.
“Congratulations to the recovery team here at Rocket Lab on a flawless mid-air recovery test,” Beck said in a statement. “Electron has already unlocked access to space for small satellites, but every step closer to reusability is a step closer to even more frequent launch opportunities for our customers. We’re looking forward to pushing the technology even further this year and bringing a flown stage back to the factory.”
Before trying the mid-air recovery after a real Electron launch, Rocket Lab plans to outfit boosters with a parachute to splash down in the ocean. Then teams will retrieve the rocket for inspections before proceeding with a helicopter catch on a later mission.
“There’s a flurry of experiments and block upgrades occurring right now for the next series of testing,” Beck said in an interview last month. “The next big milestone for recovery is actually putting on some chutes and splashing down in the ocean. That will occur later on this year.”
Beck said the first launch with a parachute could be as soon as Flight 17 of the Electron rocket, which is planned in late 2020. The next flight is Flight 12.
Rocket Lab is tackling the rocket recovery project in three ways, according to Beck.
“The first pillar — and it’s by far the hardest one — is can we make it through the atmosphere in one piece,” he said. “We’ve proven that we can do that successfully, not just once but a couple of times in a row. Then the next pillar is can we get it under a parachute and slow it to a descent rate where it doesn’t obliterate itself in the ocean when it impacts, which is another complicated thing, but nowhere near as complicated as getting it through the Earth’s atmosphere.
“And then the third pillar is can we successfully scoop something out of the sky with a helicopter,” Beck said.
Rocket Lab’s Electron rocket is small by launch vehicle standards, standing around 55 feet (17 meters) tall with a diameter of 3.9 feet (1.2 meters). The Electron’s first stage measures around 40 feet (12 meters) tall.
The Electron is designed to deliver a payload of up to 330 pounds (150 kilograms) to a 310-mile-high (500-kilometer) sun-synchronous orbit, providing dedicated rides to space for small satellites that might otherwise have to launch as a secondary passenger on a larger rocket.
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