THE RS-25 ROCKET THE MOST POWER ROCKET TO DATE WILL EVENTUALLY SEND HUMANS TO MARS GETS CLOSER TO ITS FINAL TEST OF ITS 4 ENGINES AS THE 6TH OF 7TH TEST FIRING CONCLUDED AUGUST 13TH–THE RS-25 HAS BEEN OPTIMIZED IN EFFICENCY, THRUST, AND WEIGHT TO THRUST RATIO

At 4:30 p.m. EDT on August 13, 2015, NASA conducted a developmental test firing of the rocket's engines at its Stennis Space Center in Mississippi, the sixth in a series of seven tests for the rocket's main engine. Four RS-25 engines and two solid rocket boosters of five segments each will power the 70-metric-ton rocket configuration into deep space.

"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.

"When you're looking at designing a rocket engine, there are several different ways you can optimise it. You can optimise it through increasing its thrust, increasing the weight to thrust ratio, or increasing its overall efficiency and how it consumes your propellant. With this engine, they maximised all three."

The resulting engine, according to Martin Burkey of the SLS strategic communications team, blows everything we currently have out of the water.

"The RS-25 makes a modern race car or jet engine look like a wind-up toy," he said in a post on NASA's Rocketology blog.

"It has to handle temperatures as low as minus 400 degrees where the propellants enter the engine and as high as 6,000 degrees as the exhaust exits the combustion chamber where the propellants are burned. It has to move a lot of propellants to generate a lot of energy. At the rate the four SLS core stage engines consume propellants, they could drain a family swimming pool in 1 minute."

The RS-25 produces 512,000 pounds of thrust, which is over 12 million horsepower. It's powered by four turbopumps that each generate 100 horsepower for each pound of weight, with a main shaft that rotates at a rate of 37,000 rpm, compared with 3,000 rpm for a car engine traveling at 60mph (96.5km/h).

"The RS-25 is about the same weight and size as two F-15 jet fighter engines, yet it produces eight times more thrust. A single turbine blade the size of a quarter -- and the exact number and configuration inside the pump is now considered sensitive -- produces more equivalent horsepower than a Corvette ZR1 engine," Burkey wrote.

http://www.cnet.com/news/nasa-tests-the-ferrari-of-rocket-engines-for-mission-to-mars/