Post-Decadal White Paper: A Dual-Satellite Dark-Energy/Microlensing NASA-ESA Mission

TL;DR

This paper proposes launching two specialized, narrowly focused satellites—one optical and one infrared—to perform complementary dark-energy and microlensing experiments more efficiently and securely than current multi-purpose missions.

Contribution

It introduces a dual-satellite mission concept with simplified designs, enabling faster, cheaper, and more secure dark-energy and microlensing science compared to existing plans.

Findings

Two satellites would perform complementary dark energy experiments.

The optical satellite could be launched quickly by ESA.

The infrared satellite would follow after budget constraints are met.

Abstract

A confluence of scientific, financial, and political factors imply that launching two simpler, more narrowly defined dark-energy/microlensing satellites will lead to faster, cheaper, better (and more secure) science than the present EUCLID and WFIRST designs. The two satellites, one led by ESA and the other by NASA, would be explicitly designed to perform complementary functions of a single, dual-satellite dark-energy/microlensing ``mission''. One would be a purely optical wide-field camera, with large format and small pixels, optimized for weak-lensing, which because of its simple design, could be launched by ESA on relatively short timescales. The second would be a purely infrared satellite with marginally-sampled or under-sampled pixels, launched by NASA. Because of budget constraints, this would be launched several years later. The two would complement one another in 3 dark energy experiments (weak lensing, baryon oscillations, supernovae) and also in microlensing planet searches. Signed international agreements would guarantee the later NASA launch, and on this basis equal access of both US and European scientists to both data sets.