Rocket Lab's next mission will include its first attempt at recovering the first-stage of one of its Electron rockets and bringing it back to Earth.
Previously, the first-stage, which accounts for most of the 28m tall Electron's height, has burned up re-entering the atmosphere after it separates.
The reusable rocket plan will be implemented in two phases - and is a bit more Kiwi/No.8 wire than Space X's effort, which sees its stages return to Earth under engine power to (mostly) make vertical landings.
The first phase will be implemented with Rocket Lab's "Return to Sender" mission mid-month. It will see the company attempt to recover a full Electron first stage from the ocean downrange of Launch Complex 1 at Mahia and have it shipped back to Rocket Lab's production complex for refurbishment.
The second phase will see Electron's first stage captured mid-air by helicopter before the stage is transported back to Launch Complex 1 for refurbishment and relaunch. Rocket Lab plans to begin first stage recovery attempts in the coming year. The company has already trialed a mid-air capture (see video below), albeit using a lightweight dummy booster.
Rocket Lab is already one of the most prolific satellite-launch operators on the planet. "Return to Sender" will be its 16th launch and its sixth this year.
But CEO Peter Beck says re-using rockets will allow an even faster turnaround time between launches.
"Recovering the first stage of a small launch vehicle is uncharted territory. What we're trying to achieve with Electron is an incredibly difficult and complex challenge, but one we're willing to pursue to further boost launch cadence and deliver even more frequent launch opportunities to small satellite operators," Beck says.
"Bringing a whole first stage back intact is the ultimate goal, but success for this mission is really about gaining more data, particularly on the drogue and parachute deployment system. Regardless of the condition the stage comes back in, we'll learn a great deal from this test and use it to iterate forward for the next attempt."
Electron's first stage will undertake the following complex manoeuvres on its journey back to Earth, Beck says:
• Approximately two and a half minutes after lift-off, at an altitude of around 80 km, Electron's first and second stages will separate per standard mission procedure. Electron's second stage will continue into orbit, where the Kick Stage will separate and deploy the satellites.
• With the engines now shut down on Electron's first stage, a reaction control system will re-orient the stage 180-degrees to place it on an ideal angle for re-entry, designed to enable it to survive the incredible heat and pressure known as "the wall" during its descent back to Earth.
• After decelerating to less than Mach 2, a drogue parachute will be deployed to increase drag and to stabilize the first stage as it descends.
In the final kilometres of descent, a large main parachute will be deployed to further slow the stage and enable a controlled splashdown.
• A Rocket Lab vessel will rendezvous with the stage after splashdown and retrieve it for transport back to Rocket Lab's Production Complex for inspection.
Electron's first stage is equipped with guidance and navigation hardware, a reaction control system, S-band telemetry, and onboard flight computer systems to support recovery. These standalone systems are dedicated exclusively to recovery and are entirely removed from the systems that carry out the primary mission functions of launch and payload deployment.
Work on Rocket Lab's recovery program began in early 2019 and the 'Return to Sender' recovery attempt follows a series of successful tests of recovery and hardware systems over the past 18 months. These include a successful mid-air recovery capture of a test rocket stage by a helicopter; successful drogue and main parachute deployment tests in subsequent mock stage exercises dropped at altitude; and successfully guided re-entries of the Electron's first stage across two real missions in December 2019 and January 2020 respectively.
The launch window for the Return to Sender mission will open on November 16.