Compatibility Issues Further Complicate Decision on Europa Clipper Launch Vehicle

Compatibility Issues Further Complicate Decision on Europa Clipper Launch Vehicle

NASA is growing increasingly concerned about making a final decision on what launch vehicle will be used to send Europa Clipper to Jupiter’s moon in 2025. Congress insists NASA’s Space Launch System (SLS) be used, but it is substantially more expensive than a commercial rocket and now compatibility issues are arising.

Lori Glaze, Director of NASA’s Planetary Science Division, revealed the compatibility concern at a meeting of the Planetary Science Advisory Committee (PAC) yesterday.  The Trump Administration and Congress have been at odds for several years over congressional insistence that Europa Clipper be launched on SLS instead of a commercial rocket because of the cost differential, but this is a new complication.

“Compatibility at the moment also is not clear,” she said. “There are some issues that have been uncovered just recently so we are actually in a lot of conversations right now with Human Exploration [and Operations Mission Directorate] and others within the agency about what kind of steps we can take going forward.”

Glaze did not provide further details. A NASA spokesperson told the agency is still analyzing the situation.

“We are currently working to identify and resolve potential hardware compatibility issues and will have more information once a full analysis has been conducted. Preliminary analysis suggest that launching Clipper may require special hardware adjustments, depending on the launch vehicle. Further evaluation is needed to see if this is the case; the Planetary Science Division is working with HEO to mature the launch vehicle analyses by Critical Design Review, which is on track for December.”

The entire Europa Clipper project is the result of congressional direction. Europa, one of Jupiter’s moons, is of great scientific interest because its icy crust may cover a liquid ocean, and where there is water, there may be life. The solar system is full of fascinating objects to study and the National Academies of Sciences, Engineering, and Medicine helps NASA set priorities through Decadal Surveys conducted every 10 years (a decade). Europa came in second in the most recent planetary science Decadal Survey (Mars Sample Return was first).

But former Congressman John Culberson (R-TX), who chaired the House appropriations subcommittee that funds NASA in the 114th and 115th Congresses, is convinced there is life in Europa’s ocean and intent on finding it. He wrote into law, not just in report language, that NASA must build two Europa spacecraft, one to orbit and the other to land, and added money to NASA’s budget year after year to make it happen. Congressional support for Europa has remained steadfast even though Culberson lost his reelection bid in 2018 and control of the House changed parties.

The law requires NASA to use SLS for both spacecraft and sets launch dates, although those have slipped over the years.  NASA’s current appropriations bill (FY2020) requires the orbiter, Europa Clipper, to launch in 2025 and Europa Lander in 2027.

NASA is building the $4.25 billion Europa Clipper as directed, but has not committed to Europa Lander.

Congress and NASA also remain at odds over the launch vehicle. The Office of Management of Budget (OMB) calculates the cost of an SLS launch at $2 billion, $1.5 billion more than a commercial rocket such as Delta IV or Falcon Heavy, and is urging Congress to let NASA make the choice.  NASA’s Inspector General agrees.

Not to mention it is not clear if enough SLS rockets will be available since they are needed for the Artemis program to return astronauts to the lunar surface.

Stuck between the law and the Administration’s concerns about cost and availability, project managers have been keeping their options open, but time is running out.

In response to a PAC finding at its last meeting, Glaze told the committee yesterday that it costs $30 million a year to carry multiple launch vehicles in the plan and those costs will “rapidly accelerate” once hardware is built.


One advantage of SLS is that it is powerful enough to send Europa Clipper directly to Jupiter, while the less capable commercial rockets require gravity assists from Earth and Venus, doubling the transit time from three years to six.  That not only delays obtaining the science, but the spacecraft systems must survive that much longer in the harsh space environment.

The bottom line is that a decision needs to be made soon.  The Government Accountability Office (GAO) reported in April that “significant resources will be required to maintain multiple launch and mission trajectory plans” if the decision is not made before Critical Design Review (CDR). NASA’s statement today is that CDR is scheduled for December.

The House Appropriations Committee provided a little leeway in its version of the FY2021 NASA appropriations bill, which passed the House on July 31. The bill states SLS is to be used “if available.” The Senate has not acted yet.

SLS is built in Alabama, home state of Rep. Robert Aderholt, the top Republican on the House appropriations subcommittee that funds NASA, and Sen. Richard Shelby (R), who chairs the Senate Appropriations Committee.

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