Rocket Lab launches Electron flight 8. Company previews first stage recovery

Rocket Lab has conducted the launch its Electron rocket on its eighth mission, launching from Launch Complex 1 on the Mahia Peninsula in New Zealand. For this mission, Electron lofted four satellites into orbit for UnseenLabs and Spaceflight. The first attempt was scrubbed due to unacceptable ground winds, before recycling for a Monday launch.

Electron launch:

This mission was the fourth Electron launch of 2019 – its eighth launch overall.

“Look Ma, No Hands” on the launch pad during its wet dress rehearsal, a practice countdown to ensure that the rocket will operate properly on launch day. Credit: Peter Beck

Like most missions, Electron carried its kick stage, powered by the 3D-printed Curie engine. The kick stage is able to precisely deploy satellites into different orbits, then deorbit itself at the end of the mission.

The two customers for this launch were UnseenLabs and Spaceflight.

UnseenLabs’ satellite for this mission is named Breizh Reconnaissance Orbiter 1 (BRO-1). BRO-1 will be the first satellite in UnseenLabs’ future marine surveillance constellation. This will allow ship owners to not only track their own ships, but also others that may be hazardous – including pirates and illegal vessels.

Rendering of UnseenLab’s future constellation. Credit: UnseenLabs

The other three satellites on the flight were manifested by Spaceflight. Spaceflight arranges rideshare missions for multiple smallsat customers. Past Spaceflight missions include Electron Flight 7 – nicknamed “Make It Rain” – SpaceX’s SSO-A flight, and smallsat deployments from the International Space Station.

The first of the three satellites are BlackSky’s Global-4. Global-4 will join the 3 Global satellites already on orbit, continuing the expansion of BlackSky’s constellation. Eventually, BlackSky aims to have a 60-satellite Global constellation in orbit.

Global-4’s identical predecessor, Global-3, being integrated to Electron’s kick stage for the Make It Rain mission. Credit: Rocket Lab

The Global constellation will image the Earth’s surface with a resolution of approximately one meter. Their customers can either purchase existing imagery or request for the satellites to observe an area in the future.

The Global satellites each have a three-year lifespan, therefore BlackSky plans to replace the entire constellation every three years.

The last two satellites on this mission are part of a demonstration mission for the United States Air Force Space Command, named “Pearl White”. The two 6U CubeSats will test new methods for power, propulsion, communication, and drag. They will operate in a 540km, 45-degree orbit. They were built by Tiger Innovations, Inc., who will operate them during their one-year mission.

On launch day, the road to the launch site was closed at T-6 hours. Electron – supported by the strongback – was raised vertical at T-4 hours. RP-1 fuel was then loaded into the first and second stages. At T-2 hours 30 minutes, the launch pad crew departed the site.

At T-2 hours, Electron’s first and second stages were filled with liquid oxygen (LOX), and the marine safety zones activated. These ensure that no ships will be under or near the rocket’s trajectory – which would pose a threat to anyone onboard.

At T-30 minutes, the airspace safety zones were activated. These ensure that no aircraft are near the rocket while it launches, which – like ships in the marine safety zones – would be at risk from the launching rocket.

At T-18 minutes, the launch director conducted a go/no go poll of the launch operators. This poll is conducted to confirm that all systems on Electron are ready for launch.

Electron’s onboard computers took control of the mission and began the launch sequence at T-2 minutes.

Finally, the first stage’s nine Rutherford engines ignited at T-2 seconds, and – following a quick check by the onboard computers – liftoff occurred at T-0.

Main Engine Cutoff (MECO) – when the nine first stage engines shut down – occurred at T+2 minutes 35 seconds. Three seconds later, the first and second stages separated. The second stage’s vacuum-optimized Rutherford engine ignited four seconds later, propelling the payloads into Low Earth Orbit (LEO).

View from an onboard second stage camera of the Electron “Still Testing” rocket during its successful launch in January 2018. Credit: Rocket Lab

At T+8 minutes 55 seconds, the second stage’s Rutherford engine shut down. This was followed 4 seconds later by the separation of the kick stage.

After separation, the kick stage coasted until T+50 minutes 21 seconds. The kick stage’s Curie engine then ignited for a 1 minute 27 second burn.

Payload deployment began at T+53 minutes 30 seconds and was deemed successful.

Steps towards first stage recovery:

This flight came after Rocket Lab noted its first stage recovery program was officially in work.

Peter Beck – the CEO of Rocket Lab – announced on August 6 that they will begin working towards recovering the first stage of Electron.

Electron booster under chute – as envisioned by Mack Crawford for NSF/L2

The method to recover the stage will be very different from that of the Falcon 9. While Beck shared some details at the announcement event, much of the recovery method is proprietary.

Following MECO, the first stage will not perform any additional propulsive maneuvers. Instead, it will survive re-entry using a thermal protection system mounted at the base of the stage.

Electron already has a thermal protection system, whose primary purpose is to shield the bottom of the stage from the heat of the nine Rutherford engines.

It is unclear if the existing system is sufficient to help the stage survive re-entry, or if additional protection will be needed.

Rendering of Electron’s first stage re-entering Earth’s atmosphere. Credit: Rocket Lab

After passing through the toughest parts of re-entry, the stage will deploy a supersonic decelerator – also known as a “ballute”. The decelerator will be used to slow the stage to subsonic speeds, where a traditional parafoil will deploy – slowing the stage even further.

For the first few tests, the stage will slowly descend to a soft landing in the ocean. The stage will then be recovered by a ship, refurbished, and reflown. Later flights will see the stage being grabbed mid-air by a helicopter, preventing any saltwater corrosion on the stage. This will dramatically simplify refurbishment of the stage and may allow Rocket Lab to skip refurbishment altogether.

Rendering of Electron’s first stage after deployment of its parafoil. Credit: Rocket Lab

On the past two Electron missions – Flights 6 and 7 – Rocket Lab collected data from the stages as they re-entered the atmosphere. This allowed them to understand how the stages behaved prior to and during re-entry.

For this flight, Rocket Lab has installed an advanced data collection device on the first stage that they have nicknamed Brutus. Brutus will be attached to the stage for its entire flight – from liftoff to splashdown. It will provide Rocket Lab with even more data on how the stage performs during re-entry – even after the stage breaks apart.

Brutus is designed to withstand splashdown and will be picked up by recovery crews for analysis. Its data will be used to perfect the techniques for controlling the stage prior to, during, and after re-entry.

On Flight 10, Rocket Lab plans to debut the Electron first stage block upgrade. Beck has stated that the block upgrade will increase the performance of the stage – potentially enough to negate the added mass of the recovery hardware.

Rocket Lab has not yet made public when they plan to begin recovering first stages.

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