When it's finished, NASA's new rocket will be a beast. Taller than the Statue of Liberty, with the same amount of thrust as 13,400 locomotive engines and able to carry 154,000 pounds of payload, the same, as the space agency points out, as 12 elephants.

In an effort to show the progress of the new rocket, called the Space Launch System, NASA released a video showing crews building the rocket. And it also added a scene from a 2011 test of one of the three boosters giving an impressive display of its fire power at a Utah test range. Laying on its side, the rocket ignited with a concussive blast, then blasted a gush of fire out its tail at Mach 3, or three times the speed of sound. The great plume of smoke could be seen for miles.

Take a look:

NASA tests what it says are the most powerful solid rocket boosters ever built, which will be necessary for future missions to asteroids and to Mars on NASA's new rocket, the Space Launch System (SLS). (NASA's Marshall Center via YouTube)

Officials intend to use SLS to launch the new Orion space capsule on deep space missions, including to Mars. Orion recently went through an important test--flying on an unmanned 41/2-hour mission that sent a spacecraft designed for humans farther than any has gone in more than 40 years.

But while NASA heralds the SLS as the "world's most powerful rocket," it also has some powerful critics. Members of Congress have taken aim at the program, which is still in development and isnt expected to have its first test flight for another several years. (The recent Orion mission was aboard a Delta IV Heavy rocket built by the United Launch Alliance.)

After its first test flight in 2018 originally planned for 2017 but delayed because of funding issues SLS is then expected to perform its first manned flight in 2021.

But after that flight, future mission destinations remain uncertain, the GAO has said.

And at a recent Congressional hearing, Rep. Dana Rohrabacher (R-Calif.) said it could cost at least $10billion to develop this monstrous rocket project and called it a mistake.

Marco Caceres, a senior space analyst with the Teal Group, has also raised questions about the program.

Continue reading here:

NASA just released a video of the rocket that it says will take astronauts to Mars