The plumes were first spotted by the Hubble in 2012. Since then, a robotic mission to explore Europa has slowly worked its way into existence. Congress has written into U.S. law that a Europa mission should launch in 2022 with a follow-on lander in 2024. Both would use the Space Launch System rocket to arrive at Europa in three years. NASA has resisted this rapid pace, since it would require increased funding for its Planetary Science Division, which is not a high priority for the agency at the moment.

This story of the politics behind a Europa mission is full of missed opportunities and baffling institutional resistance. Congress had appropriated over $200 million for a mission to explore the jovian moon before NASA officially requested the mission in mid-2015. Even then, NASA proposed a mission that would launch in “the mid-to-late 2020s”, which, due to the great distance between Earth and Jupiter, meant that any science return would be pushed off into the 2030s.

Since 2013, Planetary Society members and supporters have sent 384,000 messages to the White House and Congress in support of a mission to explore Europa. We’ve made huge progress since we began, but every year has been a battle to move this mission forward. This budget cycle has been no exception.

NASA requested $125 million less for Europa in next year than it received in 2016. A House bill would give much more—$260 million—but the entire U.S. budget is wrapped up in election-year politics. The Senate specified no budget for Europa, and proposed a chilling $300 million cut to the Planetary Science program. If Congress cannot pass a full budget, the mission receives the lowest of all possible proposed budgets, and it is almost certain that mission would be delayed beyond the early 2020s.

So let’s review the situation:

Europa is a prime destination for testing the hypothesis of life beyond Earth

This is because Europa has a long-lived liquid water ocean

Europa is venting liquid water into space, possibly from its deep ocean, which makes it easier to directly analyze the chemical contents of the water and potentially test the life hypothesis

A mission to Europa is blessed by the National Academies of Science, and ranked as the second-highest major mission priority after the Mars 2020 rover

Congress has repeatedly signaled its intention to fully-fund an aggressive development schedule for Europa, while maintaining balance with NASA’s planetary science program (in other words, they’ve provided “new money” for this mission)

A Europa mission solves problems for NASA’s Space Launch System rocket program while cutting travel time to Jupiter in half

I think the choice here is simple: if NASA wants to directly test the hypothesis of life living on another world, we need to get this mission to Europa going. We should also explore how an ongoing program focused on the ocean worlds of our solar system can systematically understand the habitable worlds in our own cosmic backyard.

Today is just another example that Europa is crying out for exploration. We should heed its call.