Elections have consequences; Eric Berger looks into what Culberson’s loss means for the mission. This is politically huge:
During their November briefings with Culberson, the Europa scientists were careful to say they still planned to launch the Clipper on the SLS rocket, but that has not stopped them from looking at alternatives. Until recently, there hadn’t been any good ones. However, as Goldstein said during the briefing, “We’ve had a major development, and it’s really relieving for the team.”
The development had come about as the Europa planners had worked with NASA’s Launch Services Program and SpaceX. All of the rockets available for launch today, including SpaceX’s Falcon Heavy, require multiple gravity assists to reach Jupiter, because they just could not provide Clipper the change in velocity needed to go directly to Jupiter.
Until the breakthrough, all of these rockets, including the Delta IV Heavy, needed about 7.5 years to reach Jupiter, and they also had to go into the inner Solar System to obtain a gravity assist from Venus as they ramped up energy for the outbound trip. In fact, this tortuous trajectory necessitated gravity slingshots around Earth, Venus, Earth, and finally Earth again before moving toward the outer Solar System. The mandatory Venus flyby troubled planners, because passing so close to the Sun would raise all manner of thermal challenges and require significant changes to protect Clipper from high temperatures.
The breakthrough referenced by Goldstein involved the addition of a Star 48 “kick stage” to the Falcon Heavy rocket, which would provide an extra boost of energy after the rocket’s upper stage had fired. With this solid rocket motor kick stage, Goldstein said Clipper would need just a single Earth gravity assist and would not have to go into the inner Solar System for a Venus flyby.
“Nobody is saying we’re not going on the SLS,” Goldstein said. “But if by chance we don’t, we don’t have the challenge of the inner Solar System. This was a major development. This was a big deal for us.”
Gee, I’m old enough to remember when I was cricized for saying that FH could do the job. And you know what? Star 48s have been around a long time. The only “major development” here is the ability to talk about a non-SLS Europa mission in polite company.
[Update a few minutes later]
I would note, though the article doesn’t, that while Enceladus is a tougher mission from a velocity standpoint, it’s a lot easier from a radiation standpoint.