In a Nov. 30 letter to Sen. Richard Shelby (R-Ala.), chairman of the Senate Appropriations Committee, Russell Vought, director of the White House Office of Management and Budget (OMB), discussed issues his office had with a series of fiscal year 2021 spending bills Shelby’s committee released Nov. 10. Those bills were intended to serve as the starting point in negotiations with the House, which passed its version of those bills in the summer.
Those Senate bills included a commerce, justice and science spending bill that provides NASA with $23.5 billion in 2021. The bill included language found in previous years’ bills, but not the House version for 2021, that NASA “shall use the Space Launch System as the launch vehicle for the Jupiter Europa Clipper mission.”
The White House points out that a private sector rocket, such as the Falcon
Heavy, could get the Europa mission to
the Jovian moon it's targeting although the mission would take longer. The trade off is that the
Falcon Heavy would save NASA $700 Million, which could be used on other
priorities, and moving the mission off the SLS would save one of those
rockets for the Artemis moon missions. When you combine the savings of
launch cost for the Europa probe with having an "extra" SLS booster
available, the savings climb to $1.5 Billion.
However, agency officials said in August they were studying “potential hardware compatibility issues” between the Europa Clipper spacecraft and the SLS. NASA did not elaborate on those problems, but said that “special hardware adjustments” may be needed to address them.Senator Shelby has been the strongest advocate of the SLS in the Senate because his state is the largest beneficiary of the SLS development funds. He's from Alabama, home to Marshall Space Flight Center in Huntsville, the center managing SLS development. In any program as big as SLS, there are jobs distributed around the country, allowing lots of senators and representatives to bring home the bacon to their voters if they get funding. Typical space program as income redistribution mindset.
There's also that not-so-small matter of the control of the senate not being resolved, yet, nor the presidency. If Biden becomes president over a divided government, none of this may be resolved and none of it might matter. While the Biden campaign has not talked about space policy, campaign statements such as the Democratic Party platform released this summer suggest it may at least slow the pace of returning humans to the moon, eliminating the 2024 goal established by the Trump administration. That could free up an SLS vehicle for a Europa Clipper launch in 2024, the mission’s currently targeted launch date. A real wild card is that by 2024, Starship may have achieved lunar missions and be a more viable platform to carry Europa Clipper. SpaceX may have even launched unmanned missions to Mars. At this point in Starship development, it seems unrealistic to think the program could count on the system being ready.
JPL rendering of the Europa Clipper with the moon below it and Jupiter behind, upper right.
You probably know that we're getting close to another of those "government shutdown" kabuki theater episodes. The government is running under a Continuing Resolution that expires on December 11th. Whatever this year's spending bills say, the Clipper program office wants to get the choice of booster finalized by the Critical Design Review. CDR is set for this month as well. Postponing that decision would increase the mission’s costs as they continue to support analyses for both SLS and the commercial alternative.