Watch Rocket Lab launch hypersonic scramjet vehicle for the US military today

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Liftoff of the "That's Not a Knife" suborbital mission is scheduled for 3 p.m. ET today (Feb. 25).

An image of a black and white rocket launching into a blue sky
Rocket Lab's HASTE suborbital vehicle launches the "Prometheus Run" mission for the U.S. military on Nov. 18, 2025. (Image credit: Rocket Lab)

Rocket Lab will launch a scramjet-powered hypersonic vehicle for the U.S. military today (Feb. 25), and you can watch the liftoff live.

The company's HASTE suborbital rocket is scheduled to lift off today at 4 p.m. EST (2100 GMT) from Rocket Lab's Launch Complex 2 on Wallops Island, Virginia, carrying a hypersonic demonstrator called DART AE to the final frontier.

a black, knife-shaped spacecraft sits inside a white clean room

Hypersonix's DART AE vehicle will launch on Rocket Lab's suborbital "That's Not a Knife" mission on Feb. 25, 2026. (Image credit: Rocket Lab)

DART AE is a 10-foot-long (3 meters) technology demonstrator built by the Australian aerospace company Hypersonix. It's "designed to validate advanced propulsion, materials, sensors and guidance systems at real hypersonic flight conditions," the company said in a statement earlier this month.

Hypersonic vehicles travel at least five times faster than the speed of sound. They also tend to be highly maneuverable, making them tougher to intercept than ballistic missiles — and therefore quite attractive to the militaries of the U.S. and other nations.

The upcoming mission, which Hypersonix calls "Cassowary Vex," will be the first for DART AE. The demonstrator is powered by Spartan, the company's 3D-printed scramjet engine.

Scramjets inject fuel into air that's flowing through them faster than the speed of sound. That's the main difference between a scramjet and a ramjet, which deals with slower-moving air. ("Scramjet" is short for "supersonic combustion ramjet.")

Hypersonix says they use a propellant that makes their scramjet cleaner than most. "Unlike conventional scramjets powered by kerosene, SPARTAN uses hydrogen, producing zero CO2 emissions and offering a usable, low-maintenance solution for a range of high-speed defense and aerospace missions," the company said in the same statement.

DART AE will be flying today for the Defense Innovation Unit (DIU), a branch of the U.S. military devoted to adapting commercial technology for national security uses. It will be HASTE's second DIU mission, following a November 2025 launch that Rocket Lab called "Prometheus Run."

a circular mission patch showing a pointy black space vehicle in the center and the words "rocket lab," "hypersonix" "diu" and "that's not a knife" around the outer edge

The patch for Rocket Lab's "That's Not a Knife" HASTE suborbital mission. (Image credit: Rocket Lab)

As its name suggests, HASTE is a modified, suborbital version of the 59-foot-tall (18 m) Electron, Rocket Lab's workhorse orbital launcher. ("HASTE" stands for "Hypersonic Accelerator Suborbital Test Electron.")

HASTE is a testbed, providing "reliable, high-cadence flight test opportunities needed to advance hypersonic and suborbital system technology development," according to Rocket Lab's website.

The suborbital rocket debuted in June 2023. Today's mission, which Rocket Lab calls "That's Not a Knife," will be its seventh flight to date. DART AE required a 14.1-foot-long (4.3 m) payload fairing — the longest custom-built HASTE fairing yet, according to Rocket Lab.

Electron, meanwhile, now has 75 launches under its belt.

Mike Wall
Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with Space.com and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.

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