NASA has unveiled the design for the new rocket that is expected to enable astronauts to explore Mars "and beyond" in coming years.

The Space Launch System or SLS is expected to blast off on its first test mission at the end of 2017, NASA announced at a news conference Wednesday. It is designed to allow astronauts to explore the area between the Earth and the moon, near-Earth asteroids, Mars and its moons "and beyond."


NASA expects the rocket, shown in this artist's conception, to blast off on its first test mission in 2017. ((NASA))

According to NASA, the spacecraft will be the first exploration-class vehicle since the Saturn V took U.S. astronauts to the moon more than 40 years ago.

The rocket will rely mainly on liquid hydrogen and liquid oxygen fuel and will initially also use solid rocket boosters. Its core stage will use technology from the space shuttle program, which ended earlier this year. Its upper stage will use an engine built by East-Hartford, Conn.-based Pratt & Whitney Rocketdyne, which is derived from technology developed during the Apollo moon missions.

Initially, the rocket will be able to lift 70 tonnes, but will be upgradable to lift up to 130 tonnes.

That is significantly more than the space shuttle and the biggest current unmanned rocket, which could each carry only around 24 tonnes. However, it is comparable to the Saturn V, which could carry nearly 120 tonnes.

The rocket's main job will be to carry the Orion Multi-Purpose Crew Vehicle, a capsule under development to transport astronauts beyond low-Earth orbit, as well as cargo and science experiments. Low-Earth orbit refers to the area of space near Earth where the International Space Station, the main recent destination for previous spacecraft, is located.

NASA said it had chosen the design of the SLS because of the way the spacecraft can be upgraded or customized for each mission "to achieve the most efficient launch vehicle for the desired mission."

Bill Nelson, a Democratic senator from Florida, estimated Wednesday that the program would cost $18 billion over the next five years or $3 billion a year. The Associated Press said it had previously heard from  "senior administration sources" that the rocket could cost as much as $35 billion.

All figures are US dollars.

Anonymous officials also told The Associated Press that NASA expects to build and launch about one rocket a year for 15 years or more in the 2020s and 2030s. The 2017 test flight will be unmanned, the first crew will fly in 2021 and the plan is for astronauts to visit a nearby asteroid in 2025, the officials said. They hope to land on Mars in the 2030s. 

The officials said they didn't want to be named because no official announcement about the detailed future plans had yet been made.

With files from The Associated Press