Editing RL10 (section)

===Early 2010s possible successor===
In 2012 NASA joined with the US Air Force (USAF) to study next-generation upper stage propulsion, formalizing the agencies' joint interests in a new upper stage engine to replace the Aerojet Rocketdyne RL10.
{{blockquote|"We know the list price on an RL10.  If you look at cost over time, a very large portion of the unit cost of the EELVs is attributable to the propulsion systems, and the RL10 is a very old engine, and there's a lot of craftwork associated with its manufacture. ... That's what this study will figure out, is it worthwhile to build an RL10 replacement?" |author=Dale Thomas, Associated Director Technical, Marshall Space Flight Center<ref name=FG2012/>}}

From the study, NASA hoped to find a less expensive RL10-class engine for the upper stage of the [[Space Launch System]] (SLS).<ref name=FG2012/><ref name=NASA-2012-04/>

USAF hoped to replace the Rocketdyne RL10 engines used on the upper stages of the Lockheed Martin Atlas V and the Boeing Delta IV [[Evolved Expendable Launch Vehicle]]s (EELV) that were the primary methods of putting US government satellites into space.<ref name="FG2012">{{Cite web |last=Roseberg |first=Zach |date=April 12, 2012 |title=NASA, US Air Force to study joint rocket engine |url=http://www.flightglobal.com/news/articles/nasa-us-air-force-to-study-joint-rocket-engine-370660/ |access-date=June 1, 2012 |publisher=Flight Global}}</ref> A related requirements study was conducted at the same time under the Affordable Upper Stage Engine Program (AUSEP).<ref name="NASA-2012-04">{{Cite web |last=Newton |first=Kimberly |date=April 12, 2012 |title=NASA Partners With U.S. Air Force to Study Common Rocket Propulsion Challenges |url=https://www.nasa.gov/centers/marshall/news/news/releases/2012/12-040.html |url-status=dead |archive-url=https://web.archive.org/web/20170624235440/https://www.nasa.gov/centers/marshall/news/news/releases/2012/12-040.html |archive-date=June 24, 2017 |access-date=January 10, 2018 |publisher=NASA}}</ref>