The Low Density Supersonic Decelerator was lifted by balloon 120,000 feet into the air from the Hawaiian island of Kauai on Saturday.
The vehicle then rocketed even higher before deploying a novel inflatable braking system.
But control cheers rapidly died as a gigantic chute designed to slow its fall to splashdown in the ocean emerged tangled.
Still, NASA officials say it's a pretty good test of technology that might one day be used to deliver heavy spacecraft — and eventually astronauts — to Mars.
NASA plans a news conference on the flight Sunday.