With a planned launch in the mid-2020s, WFIRST would survey distant galaxies looking for the effects of dark matter, that mysterious stuff that can’t be seen or touched but outnumbers normal matter by roughly 5 to 1. The telescope would study Type Ia supernovas to track dark energy, that strange repulsive force that is causing the universe to expand faster and faster. The observatory could even use its instruments to explore the planets around other stars.