Mercury is a small, rocky planet about which researchers know relatively little. Two missions, taking readings as they passed over the planet, have revealed that Mercury is covered by an iron-poor and sulfur-rich crust. It is also reduced, a chemical state in which the substances have gained electrons. In fact, it’s the most reduced planet in the solar system.

The Perseus Cluster is a massive galaxy cluster located in the constellation Perseus. It is one of the largest structures in the observable universe, comprising more than a thousand galaxies—equivalent to roughly a thousand trillion times the mass of the sun. Hot gases within the cluster, known as the intracluster medium (ICM), emit powerful X-rays detectable by telescopes. These gases are produced by billions of supernova explosions, and their chemical composition reveals how typical supernovae have exploded throughout cosmic history.

The Dark Energy Spectroscopic Instrument (DESI) has successfully completed the largest high-resolution 3D map of the universe ever made, a major milestone in understanding the force driving cosmic expansion. The milestone was reached when DESI’s 5,000 fiber-optic sensors captured their final scheduled observations, targeting a region of sky near the Little Dipper.

Engineers love a good practical challenge, especially when it comes to spaceflight. But there’s one particular challenge facing the crewed missions of the near future that scares mission planners above almost all others—fire. For decades, we’ve relied on a NASA test known as NASA-STD-6001B to screen material flammability for flight. But space is much more complicated than an Earth-bound test provides for. A new paper from researchers at NASA’s Glenn Research Center and Johnson Space Center and Case Western Reserve University details a planned mission to test the flammability of materials on the moon’s surface—where they expect flame to act much differently than it does here on Earth.