Rocket Lab is set to launch a mystery mission from Virginia. What could it be?

Rocket Lab is gearing up to launch a mission from the U.S. East Coast in the next few days, but you won’t be able to watch it live.

NASA’s Wallops Flight Facility in Virginia announced via Twitter on Tuesday (June 13) that it’s “scheduled to support a Rocket Lab launch between June 15-20 in the evening.”

California-based Rocket Lab regularly webcasts launches of its Electron orbital rocket, but we won’t get to see this liftoff online: “There is no livestream planned for launch, and the Wallops Visitor Center will not be open for launch,” Wallops officials added in the Tuesday tweet.

Related: Rocket Lab launches 1st Electron booster from US soil in twilight liftoff

So, what could this unusually hush-hush mission be? It’s unclear, but the circumstantial evidence points to the first-ever liftoff of Rocket Lab’s new suborbital testbed rocket.

That launcher is called HASTE, short for “Hypersonic Accelerator Suborbital Test Electron.” As that name suggests, HASTE is derived from the workhorse Electron and is designed to help test technologies for hypersonic craft — highly maneuverable vehicles capable of flying at least five times the speed of sound.

HASTE can haul up to 1,540 pounds (700 kilograms) of payload aloft, whereas Electron can deliver a maximum of 660 pounds (300 kg) to low Earth orbit. The suborbital rocket also features a modified version of Electron’s “kick stage” specialized for the deployment of hypersonic payloads, Rocket Lab said in an April 17 statement that announced HASTE’s existence.

The suborbital rocket is scheduled to make its debut right about now, on a mission whose details are hard to come by, according to that statement.

“HASTE provides reliable, high-cadence flight test opportunities needed to advance hypersonic system technology development, with the inaugural launch scheduled to take place in the first half of 2023 for a confidential customer,” Rocket Lab representatives said in the statement.

HASTE will be operated primarily by Rocket Lab National Security, a wholly owned subsidiary of the company dedicated to launching missions for the defense and intelligence communities of the United States and its allies.

The new suborbital rocket will launch only from Rocket Lab’s pad at Wallops, the April 17 statement added. (The company also has a launch complex on the Mahia Peninsula, on the North Island of New Zealand.)

So it seems likely that HASTE is the mystery vehicle flying from Wallops in the next few days. We’ll keep our eyes and ears open for any confirmation from Rocket Lab that this indeed the case.