time, and everything else. Some of this matter coalesced into stars and galaxies, however, much of the matter that is thought to make up the universe is unobserved. In truth, people don't fully know what makes up most of this "dark matter," however, several ideas exist. One such idea hypothesizes that some of this unobserved matter (the significant portion of baryonic matter) is extremely hot gas of protons and free electrons. Because these electrons are not recombining the gas interacts very poorly with light. Boston University's SPIDR satellite is designed to detect and measure this gas.

The gas is primarily between the range of 10⁵ to 10⁶ degrees, meaning it radiates any light it gives off in the ultraviolet portion of the spectrum. The spectrometer onboard the SPIDR satellite (left) will be able to trace these ultraviolet emissions across the sky and through redshifts.

From the information gathered by the SPIDR satellite (which will closely resemble the raw data to the right) deep 8 degree by 8 degree and 2.5 degree by 2.5 degree high resolution maps will be produced.