SpaceX says Starship can beat ‘plasma blackout’ with Starlink antennas

SpaceX has asked the FCC to allow Starship and its Super Heavy booster to communicate with Starlink during the rocket’s first orbital launch attempt, potentially unlocking game-changing capabilities.

Filed on June 28th, SpaceX’s Special Temporary Authority (STA) application contains a number of surprising details about the company’s plans to expand the experimental use of its Starlink satellite constellation to communicate with rockets in flight. That effort was first made public in April 2021 when a separate FCC application revealed plans to test Starlink on a Starship prototype. Starship serial number 15 (now known as Ship 15 or S15).

That particular prototype became the first of its kind to successfully launch and land in one piece on May 5th. Nothing is known about whether Starlink was actually used or how the Starship’s lone dish performed during the 10 kilometer (6.2 mi) flight test, but SpaceX’s plans to again combine both two Star– programs do offer some new lines to read between.

Relative to its first Starlink-Starship STA application, SpaceX splits no hairs in the ‘narrative’ attached to its latest request. Specifically, SpaceX repeatedly discusses the potential for Starlink to drastically improve the state of the art of routine spacecraft and launch vehicle telemetry and communications.

“SpaceX intends demonstrate high data rate communications with Starship and the Super Heavy Booster on the ground at the launch site in Starbase, TX during launch, during booster recovery, in flight, and during reentry. Starlink can provide unprecedented volumes of telemetry and enable communications during atmospheric reentry when ionized plasma around the spacecraft inhibits conventional telemetry frequencies. These tests will demonstrate Starlink’s ability to improve the efficiency and safety of future orbital spaceflight missions.

SpaceX — June 28th, 2021

In short, in the two months since SpaceX first requested permission “to operate a single user terminal…during flight tests,” the company appears to have become extremely bullish about Starlink’s potential as a solution for rocket communications. The logical conclusion is that Starlink performed well during its trials aboard Starship S15 on the ground and in flight – possibly even exceeding SpaceX’s own expectations. Simultaneously, SpaceX is in the midst of expanding efforts to certify Starlink for aviation communications and has been generally ramping up tests on aircraft, ships, and road vehicles.

Indeed, at least in theory, the same attributes that allow Starlink to blow traditional consumer satellite communications solutions out of the water could make Starlink a boon for launch vehicle communications. That’s especially true for the test flights of experimental launch vehicles like Starship, where failure is an inevitable part of the development process. However, those launch failures are only beneficial insofar as they expand the knowledge base and allow lessons to be learned.

Falcon 9’s main telemetry antenna is visible on the booster’s interstage. (Richard Angle/BocaChicaGal)

Data, in other words, is essential, and the more data recovered from test flights, the better. Even on modern rockets, state-of-the-art telemetry usually involves maximum bandwidth on the order of a few hundred to a few thousand kilobits per second, often requiring software and compression gymnastics and uncomfortable triage to ensure that all necessary telemetry keeps flowing.

If Starlink could expand that bandwidth from a few megabits per second (Mbps) to dozens or even hundreds of Mbps, SpaceX could extract unprecedentedly widespread and high-resolution telemetry from Starship and Super Heavy during their first orbital test flight, leaving a wealth of data for likely post-flight failure analyses.

A Starship enters the Martian atmosphere in this artist’s impression. (SpaceX)

Perhaps most surprising is SpaceX’s claim that Starlink antennas could allow Starship to maintain a strong communications link throughout orbital reentry. Traditionally, all spacecraft capable of reentry produce a superheated sheath of plasma as they careen into Earth’s upper atmosphere. That plasma effectively blocks most radio waves, creating an inevitable several-minute communications ‘blackout’ for any reentering spacecraft.

If Starlink can somehow allow SpaceX to break through that ‘plasma barrier,’ it would give the company an unprecedented capability invaluable for the process of perfecting orbital Starship reentry, descent, and landing – a process Musk expects to involve several unsuccessful attempts. According to SpaceX’s FCC application, Starship’s first orbital launch and reentry attempt could occur as early as August 2021.

SpaceX says Starship can beat ‘plasma blackout’ with Starlink antennas
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