NASA has been testing an engine that could be used in the next generation of space launches, with tests including a nine-minute "hot fire" of the engine at Stennis Space Center in Mississippi.

The RS-25 is designed to launch the Orion spacecraft, which will eventually be used to carry humanity to Mars, the next big frontier in physical space exploration. It might even take us beyond Mars.

The nine-minute test launch is the same time that the engines will fire when launching the Space Launch System megarocket, which will be powered by four of these engines. The test is the sixth test in a series of seven given to the engines.

"It is the most complicated rocket engine out there on the market, but that's because it's the Ferrari of rocket engines," said Kathryn Crowe, RS-25 propulsion engineer, in an interview with CNet. 

Kathryn went on to talk about the design of the engine, saying that there are a number of ways that a rocket can be optimized. For example, the thrust is one factor that must be taken into consideration, however, things like weight and thrust ratio are also important factors and ones that could ultimately affect how efficient the engine is and how much propellant it consumes.

The engine is able to handle massive strain and pressure without any issues. It produces 512,000 pounds of thrust, or 12 million horsepower, and is powered by a total of four turbopumps, with each of those turbopumps able to generate 100 horsepower for every pound of weight. It also includes a main shaft that rotates at 37,000 rpm. To put that into perspective, car shafts rotate at around 3,000 rpm when traveling at 60 mph.

The engine itself is actually around the same size and weight as two F-15 jet fighter engines. Despite this, the RS-25 is able to produce eight times the thrust of two fighter jet engines. 

While the engines can handle such huge power, the smallest hitch can cause big problems, especially at speeds as high as the engines can bring a rocket to. That's why such extensive testing is being put into the engines while they are on the ground, before there is any kind of actual launch.

It is expected that the engines will launch for the first time with the Orion capsule in 2018, which will be an unmanned journey around the moon aimed at doing further testing. The goal is to eventually send people Mars by the mid 2030s.