MIAMI (AFP) - The most powerful solid rocket booster ever built was fired up for the first time Wednesday in a test that Nasa described as a "significant milestone" towards Mars.
Tied horizontally to the ground at the base of a Utah mountain, the 54m-long Space Launch System (SLS) booster was hot-fired for two minutes to see how the system would perform when eventually launched.
"Great test, just a fantastic result," said Alex Priskos, who manages the Boosters Office for the SLS programme at Nasa's Marshall Space Flight Centre in Huntsville, Alabama.
"This thing was about as perfect... as it could be."
Two boosters and four RS-25 rocket engines will eventually propel the SLS and the Orion spacecraft atop it to deep space destinations like an asteroid and Mars, places where humans have never before ventured.
The rocket's first test flight is scheduled for 2017, when it will be configured to lift 70 tonnes of gear into space on an unmanned Orion spaceship.
Eventually the SLS "will provide an unprecedented lift capability of 130 metric tonnes to enable missions even farther into our solar system," the US space agency said on its website.
The technology represents a big boost over the power needed to send astronauts to space during the three-decade-long shuttle era, which ended in 2011 when the programme was retired.
"These motors have 25 per cent more energy than the motors we used to get the shuttle off the ground during the space shuttle days," said Todd May, programme manager for SLS.
Eventually, the Orion multipurpose capsule aims to carry humans to Mars sometime in the 2030s, according to Nasa's plans.
Wednesday's booster test, which heated the equipment to 32 deg C, took place at ATK Aerospace System's test facility in Promontory, Utah.
A second, low-temperature test of the booster is planned for early 2016.