This weekend was the SpaceX launch-a-palooza. They managed to send up three Falcon 9 rockets in just over 36 hours: one on June 17 at 16:08 UTC, the next on June 18 at 02:19 UTC, and the last one on June 19 at 04:27 UTC.

The first of these launches was another batch of Starlink satellites, of course. Booster 1060 sent 53 more Starlinks into orbit from historic launch complex39A in Florida. A milestone set on this flight was the first thirteenth launch of a booster. It successfully landed on the droneship A Shortfall of Gravitas.

About a day later and on the opposite side of the country, another Falcon 9 launched the SARah-1 satellite into polar orbit. SARah-1 is a synthetic aperture radar satellite built by Airbus for the German military. No details about the payload were disclosed, but it was apparently light enough for the booster to perform a return to launch site maneuver, landing a couple of hundred meters from where it lifted off just a couple of minutes prior.

Vandenberg was covered in its typical marine layer of fog which obscured many of the views of the launch until the rocket had punched through the fog layer and provided some beautiful views of the California coast during the ascent, separation, and return phases of the launch. Conditions at the landing zone had improved quite a bit by the time the booster landed, presenting views with a good view of the landing.

The satellite was successfully deployed into orbit after a second burn of the upper stage. The German military later thanked SpaceX on social media for the successful ride. Two more SARah satellites will ride on Falcon 9 rockets later this year and next year.

The final SpaceX launch of the weekend was the one that had the most interest from fans. The information announced about the launch didn’t quite make sense. The primary payload was a 700-kilogram satellite going into a not particularly high orbit – about twice as high as Starlink but nowhere near geostationary Earth orbit – yet it was on a Falcon 9 with a downrange first stage landing.

The publicly known payload on the Sunday morning flight was Globalstar FM-15. Globalstar was one of the first companies to launch a satellite communications constellation back in the late twentieth century, and they launched the second generation of satellites in the mid-2010s. FM-15 was built as a ground spare for this second generation, which Globalstar has evidently decided to launch.

The other satellites on the mission were less clear, but the enthusiast community has a couple of theories based on a few pieces of evidence.

First, the mission press kit mentioned a “rideshare” indicating that more than one satellite would be onboard.

Second, the mission plan included three burns of the second stage engine prior to satellite separation. That wouldn’t make sense for a single satellite. Also, no views of the second stage were shown until an hour into the flight, after the second burn. When the forward-facing camera was finally shown, the view had the Globalstar satellite mounted sideways, with a mysterious fixture on the top of the payload stack.

Space enthusiasts on Twitter and other places, such as the fantastic NASAspaceflight forum, quickly linked this structure to a mechanism used to hold Starlink satellites on previous satellite rideshare missions, such as Transporter 2 and 3. If SpaceX was launching Starlinks along with the Globalstar sat, you would think they would mention this, right? Something else must be going on.

What semi-secret Starlink-derived satellites could SpaceX be launching? One possible answer to that question is fairly simple. In 2021, SpaceX got a contract from the Missile Defense Agency for several missile launch detection satellites using the Starlink satellite bus. It is possible the mystery satellites are early test versions of this satellite design, though they weren’t supposed to launch for another couple of months, in September 2022.

The day after launch, June 20, the satellites from the launch were finally listed in the online database Space-Track. Globalstar FM15 was added along with four other satellites simply designated USA 328 through 331 and one debris object. A USA-number is a designation given to U.S. military satellites. The debris object is probably a tension rod that held the Starlink-derived satellites together before separation.

In some ways, this is reminiscent of the Transporter 3 launch this past January, which included four undisclosed satellites riding up on a Starlink rideshare adapter.

More Information

Starlink mission page (SpaceX)

SARah-1 mission page (SpaceX)

Globalstar FM15 mission page (SpaceX)

US Military Places a Bet on LEO for Space Security (SDA)