Will the Ukraine war force ESA to pass on Arianespace, use SpaceX?

The author of this piece is part of the team that has helped developed the Euclid mission.

The European Space Agency was about to launch a billion-euro satellite that was supposed to answer the most pressing questions in astronomy: What are the true natures of dark matter and energy? There was a planned March 23, 2023 launch for Euclid, but it was on a Russian rocket. The war in Ukraine ended Soyuz operations from Guiana and caused a period of uncertainty for the team.

It would cost 100 million euros a year to keep the entire scientific team and infrastructure in storage. Arianespace, the partner of the European Space Agency, is building the Ariane 62, a good backup launch vehicle. The test flight date for that rocket has not been set yet. At least four other satellites are waiting in the queue before the first Ariane 62 launch, which is not expected until 2020.

There is a company with a rocket that has spare capacity. Would a flagship European science mission be sent to space on a rocket from Arianespace?

Tracking the Universe’s expansion

Astronomers discovered in the 1990s that the rate of expansion of the universe is increasing. To understand the nature of the acceleration, you need a ruler to measure length scales in the Universe's distant past together with a way to map the amount of intervening dark matter. The best way to distort the light of those that pass is from space above the atmosphere.

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The question was directly answered by the selection of Euclid in 2011. Two unique instruments will be used to measure the positions and shapes of a billion distant galaxies. Dark matter can be measured from the very small shape correlations in the distant background galaxies. The measures of distances, positions, and velocities are all imprinted with the action of the expansion. The geometry of the Universe can be revealed by the combination of these two measures.

Shapes are hard to measure from the ground. Thanks to technological advances, it is now easier to collect a lot of distance data. The main Euclid survey will take six years to complete and it needs to be launched as soon as possible.

A group of European research institutions collaborated with NASA to build the instruments. Both the telescope and the service module were built by the same company. After integration is complete, the satellite will be shipped to France for final testing. On what platform?