On Thursday, NASA’s new large rocket, the Space Launch System, will make a second attempt to get nowhere.

This test, known as hot fire, is a critical step for the rocket, which has been in development for more than a decade. The four motors on the booster stage fire and run through the steps they would take during an actual launch into orbit – but while held firmly to earth.

When NASA first attempted this hot fire test in January, the engines came to life. But instead of firing for eight minutes, the rocket’s computer shut down the engines in just a minute or so.

The engineers decided they needed a makeover, and today is the day for it.

The rocket is currently supposed to ignite its engines on Thursday at 3 p.m. east coast time. NASA has a two hour window in which to try the test fire.

The test will be broadcast live on NASA television. Coverage begins about 30 minutes before the rocket ignites.

However, this trial period could be changed. During the last test fire event in January, the agency briefly moved its testing time forward, stating that it was carried out ahead of schedule, before operations were postponed again later in the day.

The Space Launch System is the 21st century equivalent of the Saturn 5 that was used to take NASA astronauts to the moon in the 1960s and 1970s. Although there are many other rockets out there today, they’re too small to launch spaceships that can carry humans to the moon. One possible exception is SpaceX’s Falcon Heavy, but a human moon mission would require two separate launches carrying parts that would then dock together in space or go to the moon separately.

The Falcon Heavy can lift up to 64 tons into low earth orbit. The original version of the SLS is a bit more powerful and can lift 70 tons. Future versions of the rocket can throw up to 130 tons, more than the rockets that the Apollo astronauts transported to the moon.

Although the space launch system will be expensive – up to $ 2 billion per launch for a single-use missile – Congress has so far provided unwavering financial support for it. Supporters claim it is important for the government to own and operate its own powerful space rocket, and parts of the system are being built by companies across the country, spreading the economic benefits to many states and congressional districts.

The Space Launch System is a key component of Artemis, the program designed to bring NASA astronauts back to the moon in the years to come. Although former President Donald J. Trump promised to make the trip by the end of 2024, few expected NASA to actually stick to that schedule before President Biden was elected.

During a full eight minute test, the four engines generate more than two million pounds of thrust. But NASA officials say they need the test to run for at least four minutes to generate the data they want. The engines can do more than just fire during the test. They perform a number of activities, such as: B. throttling the thrust up and down and pivoting the direction of the nozzles.

The booster stage – NASA calls it the core stage – is mounted on a huge test bench in the Stennis Space Center in Mississippi. The same test rig was used to test the first stages of the Saturn 5 in the 1960s. The structure was also used during the development of the space shuttle.

Due to the size of the core stage of the Space Launch System – more than 200 feet high and 27.6 feet wide – the test stand was modified with an additional steel structure.

The engines in the SLS core stage are not new, but the ones that were used by the space shuttles. This used, space-flown hardware has been refurbished and upgraded for use on the new rocket.

The engines shut down early – after just 67 seconds – and as a result, NASA decided it wanted to collect more data to verify that the rocket was working properly during a real launch.

With the same core stage slated to launch later this year with no astronauts on board, engineers had to make sure the test didn’t damage that part of the rocket. As a result, they set some parameters as “conservative” that would stop the test if something was wrong. It did so with the aggregate swiveling the nozzle of one of the engines, although officials said it would not have caused a problem during an actual launch.

A second failure, indicating a “major component failure” on another engine, had nothing to do with it and would not have caused the test to stop or a problem to be raised during a start. As a result of this error, a defective electronic device was replaced.

Engineers are confident that they fixed the issues from the first step, but other glitches may arise as well.

A worst case scenario would be if a malfunction led to the destruction of the booster. This would delay the program for years and again ask NASA to consider alternatives.