Warning issued about sonic booms during SpaceX’s first West Coast landing attempt

Jason Rhian

VANDENBERG AIR FORCE BASE, Calif. – SpaceX has made history by having the first stages of its Falcon 9 rockets conduct controlled landings. One of the side effects of those landings has been triple sonic booms – something the U.S. Air Force noted in a statement issued on Tuesday.

The SpaceX Falcon 9 rocket with the SAOCOM 1A satellite is scheduled to launch from Space Launch Complex-4E on Sunday, Oct. 7, at 7:21 p.m. PDT, a 24 hour slip from the previous launch date. SpaceX noted the change in the schedule in a Twitter post which stated the following:

Now targeting October 7 for launch of SAOCOM 1A. Rocket and payload are healthy; additional time will be used to complete pre-flight vehicle checkouts.

The landings that the Falcon 9 have become famous for are referred to as Return to Launch Site or “RTLS” for short.

There has been some confusion as to whether the first stage’s return produces two or three sonic booms upon landing. Typically, the answer is – three. “Typical” in that sonic booms are affected by the weather as well as other conditions.

“[The] first boom is from the aft end (engines),” said John Taylor, SpaceX’s former Communications Director. “[The] second boom is from the landing legs at the widest point going up the side of the rocket. [The] third boom is from the fins near the forward end.”

SpaceX carried out the static test fire of the SAOCOM-1 Falcon 9’s Merlin 1D engines on Tuesday, Oct. 2. This is one of the final milestones before the rocket leaves the pad.

However historic the location of the mission’s sonic booms might be, SpaceX’s primary focus will be on getting the communications satellite’s on its way to orbit. The landing of the rocket’s first stage at Landing Zone 4 (SLC-4W) at Vandenberg is considered to be a secondary objective.

The stage’s landing is a complex affair of engine burns, the deployment of its legs and other components which allow it to return safely back to Earth. To date, SpaceX stands alone as the only commercial company to deliver payloads to orbit and then recover and reuse part of the rocket for use on later missions. This has allowed the Hawthorne, California-based company to significantly reduce launch costs.

To date SpaceX has carried out 29 successful landings of Falcon 9 first stages. This re-usability is part of the company’s philosophy with the cargo variant of SpaceX’s Dragon spacecraft also reused and re-flown.

Sonic booms occur whenever a vehicle breaks the speed of sound. These shock waves sound similar to brief clap of thunder. Residents living in Santa Barbara as well as San Luis Obispo counties could hear the booms upon the stage’s return.

Sunday’s launch is planned so as to send the SAOCOM-1 satellite into orbit. SAOCOM 1A is an Argentine (SAR Observation & Communications Satellite).

If everything goes as planned, the SAOCOM-1 flight will be the seventeenth mission that SpaceX has conducted in 2018.

“SpaceX is excited to be CONAE’s launch service provider for the SAOCOM 1A and 1B missions,” said Elon Musk, CEO and CTO of SpaceX via a release issued in 2009. “The Falcon 9 launch vehicle has been designed to the highest level of reliability and performance; we look forward to helping ensure the success of the SAOCOM satellites.”