Sunday, November 6, 2022

Rocket Lab at 0 for 2 on Helicopter Booster Recoveries

Friday evening, east coast USA time and 6:27 AM Saturday New Zealand time, Rocket Lab launched their second mission featuring an attempt to recover the booster with a helicopter.  As usual, they provided live video so we learned what was happening as the announcers learned.  You might recall their first attempt back in May on a mission called There and Back Again in which they actually snagged the booster but then the helicopter pilot dropped it citing unusual dynamics that didn't match their test or practice scenarios.  While they succeeded in catching the booster, the goal of catching the booster in mid-air and never having it plunge into saltwater remained elusive.

Friday's mission, called Catch Me If You Can, never hooked the booster and the company reported the helicopter left the area when controllers lost telemetry from the booster.   

But ground controllers lost contact with the 39-foot-long (11.9-meter) booster stage during descent. As a safety precaution, the Sikorsky S-92 recovery helicopter flying over the Pacific Ocean to catch the booster moved out of the capture zone, “per standard safety procedure,” Rocket Lab said.

The booster splashed down under a parachute, and a recovery ship moved alongside the rocket to pull it from the sea and return it to Rocket Lab’s development and manufacturing facility in Auckland, the company said in a post-launch statement.

Rocket Lab is committed to booster re-use but the Electron booster isn't big enough to have some of the margin for extra fuel that the Falcon 9 has.  The Electron is a much smaller launch vehicle at 59 feet tall vs. 230 feet for the F9.  To use helicopter recovery vs. slowing with engines and landing on a drone ship makes sense. 

The downside to that, of course, is that booster becomes a ballistic projectile with very little control.  The booster continues upward (as the Falcon 9 booster does) slowing down before going into a free fall.  It is calculated to reach a a top speed of 5,150 mph (8,300 kilometers per hour) before aerodynamic drag starts stripping some of that velocity and turning it into heat.  The trade is that external temperatures build up to 4,350 degrees Fahrenheit (2,400 degrees Celsius).  That's hot enough to generate some plasma around the vehicle which could interfere with radio links; which must be expected.  The booster has a heat shield, which (if memory serves) was added specifically to improve the chances of recovering the booster.   

“Rocket telemetry dropped out (it happens a bit during re-entry) but we did not regain a solid link in time,” tweeted Peter Beck, Rocket Lab’s founder and CEO. “Without that link, it’s just not safe to put the helicopter into the recovery zone, so we stood it off. The great thing about recovery is you get it back to see what happened.” 

Rocket Lab will tell you that all of this is a sideshow to getting important payloads into space (for paying customers, of course).  The mission was to deliver a Swedish scientific satellite called MATS, for Mesospheric Airglow/Aerosol Tomography and Spectroscopy, into polar orbit.  The MATS mission is funded by the Swedish National Space Agency, and is designed to study waves in Earth’s atmosphere.  MATS is the first Swedish science satellite to launch in more than 20 years.

The satellite was built by OHB Sweden, and carries an instrument to image variation in light emitted by oxygen molecules in the upper atmosphere, as well as noctilucent clouds that form about 50 miles (80 kilometers) above Earth’s surface. OHB Sweden said in a post-launch press release that ground controllers established communications with the MATS satellite, confirming it to be in good health following deployment in orbit.

A satellite in good health and the right orbit is what it's all about.

The Saturday morning (in New Zealand) launch of the Catch Me If You Can mission.  Rocket Lab photo. 

1 comment:

  1. They need to hire Arnold if they want to get to the choppa.