Rocket Lab’s Electron smallsat launch vehicle successfully Returned To Flight with a mission nicknamed “I Can’t Believe It’s Not Optical”. This was the company’s first launch following an anomaly on the “Pics or it Didn’t Happen” flight that led to that mission’s failure.
For its 14th flight, Electron carried Capella Space’s “Sequoia” microsatellite to a low-Earth orbit (LEO) from Launch Complex 1 on New Zealand’s Mahia Peninsula. Liftoff occurred August 31 at 03:05 UTC (11:05 pm EDT on the 30th).
Electron’s Return to Flight:
Just over a month after experiencing a mission failure, Rocket Lab found the root cause of the anomaly and was ready to fly again.
On July 31, the company announced that the cause of the failure was pinpointed to a wire on the second stage. The wire was improperly secured, leading to it coming loose, overheating, and breaking. The breakage caused a loss of power to the electric pumps of the Rutherford vacuum engine on the second stage, leading the flight computer to shut down the engine.
Because the engine’s shutdown was controlled, Electron continued to send clean telemetry back to Rocket Lab for several minutes. The second stage coasted to a 194 km apogee before falling back to Earth.
The company also stated that no vehicle redesigns would be necessary. Moving forward, Rocket Lab will more closely inspect and test the vehicle prior to launch to ensure the issue does not reoccur.
With the investigation concluded and the root cause determined, Rocket Lab then pushed forward with Electron’s 14th mission, its Return To Flight (RTF).
On June 23, the first stage engines for Flight 14 were successfully test-fired at Rocket Lab’s New Zealand test site.
From there, all components were shipped to Launch Complex-1 (LC-1) on the Mahia Peninsula in New Zealand. Inside LC-1’s Horizontal Integration Facility (HIF), the vehicle was assembled and mounted on the transporter-erector.
Rocket Lab completed a Wet Dress Rehearsal (WDR) on August 23. A WDR involves rolling the complete Electron rocket out to the launch pad. The teams then conducted a full countdown demonstration to ensure all systems were working as expected. This included – as the name suggests – loading the rocket with liquid propellants. The countdown continued until T-0, at which point the teams paused, drained the tanks, and rolled the rocket back into the HIF for final work.
As is tradition with all their missions to date, Rocket Lab gave the launch a nickname – in this case “I Can’t Believe It’s Not Optical”.
The nickname is a nod to the Synthetic Aperture Radar (SAR) technology used on Capella’s satellites, deviating from the common optical imaging satellites.
SAR works by emitting X-band radio waves towards Earth and measuring how they reflect off the terrain. From this data, Capella is able to stitch together maps of the Earth’s surface. In addition, SAR is able to see through cloud cover and during the night – something optical imagery cannot.
Capella employs three imaging modes on their satellites to produce different results.
“Spotlight mode” involves focusing on one region during a pass. This can result in a three-dimensional view of the area, allowing the height of features to be determined.
“Stripmap mode” is similar to traditional imaging satellites where a long strip of surface is mapped by a stationary satellite. The resulting image is flat and two-dimensional, but covers a larger amount of land.
“Sliding spotlight mode” is a mix of the two. The resulting image is a three-dimensional view of a larger area of land than “spotlight mode” provides, but not as large as “stripmap mode”.
Using SAR, the satellites can achieve a surface resolution of 50 cm per pixel. For reference, DigitalGlobe’s much larger WorldView satellites – used for much of Google Maps – have a resolution of 31 cm per pixel.
The Capella satellites weigh approximately 100 kg – well-suited for Electron. Using Rocket Lab’s kick stage – a small spacecraft bus used to precisely maneuver payloads – Sequoia was injected into an approximately 570 km, 45-degree-inclined orbit.
Each satellite contains a large, deployable reflector to send out and receive radio waves for the SAR instrument.
Capella aims to have a 30 satellite constellation. With this, they will acquire hourly imagery of any spot on Earth. The imagery will then be sold to Capella’s customers. Their main market will be those interested in observing changes in the surface in close intervals.
At the moment, Capella only has one operational SAR satellite in orbit. Sequoia will be the second, followed by at least 3 more – part of the “Whitney” group of satellites – later this year.
Following this mission, Rocket Lab’s next flight will be a major step for the company.
Flight 15 will liftoff from Launch Complex 2 (LC-2) at the Mid-Atlantic Regional Spaceport at Wallops Island, Virginia. It will be the first flight from LC-2 – the second Electron pad.
That Electron will carry Monolith – an Air Force space weather monitoring satellite – to a Low Earth Orbit. The overall mission is referred to as STP-27RM, part of the Space Test Program.
LC-2 caters specifically to lower-inclination orbits. This will relieve some strain on LC-1, allowing the latter to focus on higher-inclination missions. Additionally, having a second launch pad will enable Rocket Lab to increase the overall launch cadence of Electron.
LC-2 will also be the launch site for NASA’s CAPSTONE mission. Electron will lift CAPSTONE into a translunar orbit, after which the spacecraft will maneuver itself into a Near-Rectilinear Halo Orbit (NRHO), the orbit that NASA’s Lunar Gateway will reside in.
CAPSTONE is expected to launch in early 2021 and will prove that the orbit is stable and safe for Gateway.
(Lead photo via Rocket Lab)