Axios

NASA and the Japanese space agency JAXA are moving ahead with building a new orbiting X-ray telescope to find evidence of dark matter, which is believed to make up 80% of all the mass in the universe. Dark matter doesn't emit or absorb light, and is instead detected via X-rays from the decay or annihilation of dark matter particles.

Previous joint missions were ill-fated:

• Take 1: In 2000, the first version of the telescope was lost in a launch failure.
• Take 2: X-ray detecting instruments made it into orbit in 2005 but a helium leak caused the primary one to malfunction.
• Take 3: A month after its launch in February 2016, the $273 million Hitomi telescope lost contact when the control system that stabilized it repeatedly failed, causing the satellite to spin uncontrollably and fly apart.

Why it matters: For years, scientists have been scouring the center of galaxy clusters for proof of dark matter. Several satellites have provided conflicting data about telltale X-ray signals. With resolution 20 times better than that of previous missions, the X-ray Astronomy Recovery Mission (XARM) may finally shed light on one of science's biggest questions.