Small satellite launch specialist company Rocket Lab plans to try to catch one of its launch vehicles on return to Earth, using a helicopter. We should know today if the idea is as unfeasible as it sounds, or if Rocket Lab has come up with a potential new way to recycle launch vehicles. Here's when it's happening and how to watch.

The methods that first took humanity into space and to the Moon were not sustainable. Aside from the quantities of fuel expended, dropping vast lumps of metal used to launch spacecraft on the first part of their journey in the ocean couldn't go on.

The challenge has inspired a variety of methods to recapture rockets, with SpaceX's ultimately successful process of landing its first stage on barges and launchpads the only one proven so far proven suited for reuse.

The initial process will be similar to other space launches. Rocket Lab will put 34 cubesats (small satellites) for a variety of clients on a two-stage Electron rocket. The first stage will separate 2.5 minutes after launch and then start falling back, reaching a speed of an estimated 8,300 kilometers per hour (5,150 miles per hour) under the influence of gravity. At a height of around 13 kilometers (8.3 miles), the first booster will deploy a parachute, bringing its speed down to an estimated 36 km/h (22 mph).

It might be thought this was enough for a landing with nothing more than a few bumps and dents, but people have a strange aversion to a metal object weighing as much as three elephants approaching them at the speed of an Olympic sprinter. Consequently, Rocket Lab will have a helicopter waiting, which will try to get a hook on the parachute, stopping the rocket entirely without, it is hoped, tearing the parachute.

“Trying to catch a rocket as it falls back to Earth is no easy feat, we’re absolutely threading the needle here,” Rocket Lab CEO Peter Beck said in a statement. The test doesn't come out of nowhere, however. Beck also said: “We’ve conducted many successful helicopter captures with replica stages, carried out extensive parachute tests, and successfully recovered Electron’s first stage from the ocean during our 16th, 20th, and 22nd missions.”

If you're struggling to imagine how a helicopter could carry a first-stage rocket, once caught, it might help to know Rocket Lab's Electron is less than a third the height, and one-fortieth the weight, of SpaceX's Falcon 9. At 13 tonnes at launch (lighter after using its propellant, it should be well within the carrying capacity of the Sikorsky S-92 that will perform the operation.

The launch, scheduled for today, April 29 at 10:35 pm UTC (6:35 pm ET) will take place from Rocket Lab's launch site on the M?hia Peninsula, New Zealand, with the attempted recapture occurring well offshore. Rocket Lab is live streaming the event, so you can watch it all unfold here. 

Although now headquartered in the US, Rocket Lab emphasized their New Zealand origins with a Tolkien reference, calling this the “There and Back Again” mission.

Rocket Lab may not be as familiar a name as the companies that have sent humans to space, but they can boast putting more than 1,700 small satellites in orbit, including 112 in previous Electron launches.

Low Earth Orbit has its own sustainability problems, but this mission could help there as well. Among the cubesats to be deployed are three from E-Space, a company working towards plans to capture debris in orbit before sacrificially burning up in the atmosphere. Another, from Aurora Propulsion Technologies, will trial “Resistojets” and “Plasma Brakes”, respectively designed to prevent satellites from tumbling uncontrollably and to ensure they deorbit safely when required.