The second of NASA's James Webb Space Telescope's four primary scientific instruments, known as the Mid-Infrared instrument (MIRI), has concluded its postlaunch preparations and is now ready for science.

The last MIRI mode to be checked off was its coronagraphic imaging capability, which uses two different styles of masks to intentionally block starlight from hitting its sensors when attempting to make observations of the star's orbiting planets. These customized masks allow for scientists to directly detect exoplanets and study dust disks around their host stars in a way that's never been done before.

Along with Webb's three other instruments, MIRI initially cooled off in the shade of Webb's tennis-court-size sunshield to about 90 Kelvin (minus 298 degrees Fahrenheit, or minus 183 degrees Celsius). To perform its intended science meant dropping to less than 7 Kelvin—just a few degrees above the lowest temperature matter can reach—by using an electrically powered cryocooler. These extreme operating temperatures allow for MIRI to deliver mid-infrared images and spectra with an unprecedented combination of sharpness and sensitivity.

The phrase "nuclear energy" conjures images of large steaming towers or Tony Stark's arc reactor from the iconic "Iron Man" movies. But two Seattle-based startups are designing nuclear technologies small enough to pick up and carry that, thanks in part to buy-in from the Defense Department, they hope will fuel a new generation of spaceships.

Seattle's Avalanche Energy and Ultra Safe Nuclear Corporation received undisclosed amounts of funding from the Pentagon's Defense Innovation Unit in May to further develop two different approaches to small-scale nuclear power.

Avalanche is pushing the boundaries of nuclear fusion while Ultra Safe aims to revolutionize nuclear radioisotope batteries, like those that power Mars rovers. Both companies are expected to deliver functional prototype spacecraft to the Pentagon by 2027.

"Nuclear is an interesting area because traditionally that's been mainly in the realm of government," said U.S. Air Force Maj. Ryan Weed, the program manager for the Defense Innovation Unit's nuclear propulsion and power program. The unit—the Pentagon's outpost in Silicon Valley—works exclusively with private sector companies to adapt emerging technologies for military use.

After six decades of materials science research, nuclear fuels are relatively safe and are being embraced in the private sector.

Astronauts that have returned after spaceflights over three months may show signs of incomplete bone recovery even after one year on Earth, but adding in more resistance-based exercises during spaceflight may help limit bone loss. The small study, published in Scientific Reports, on 17 international astronauts found that while the shinbone partially recovers, the sustained bone losses after one year are equivalent to ten years of normal age-related bone loss on Earth.

Steven Boyd and colleagues imaged 17 astronauts (14 male, three female) before spaceflight, at return to Earth, and after six and 12 months of recovery. They conducted bone scans on the tibia (shinbone) and radius (forearm) to calculate the resistance of the bone to fracture (failure load), bone mineral in the bone tissue, and tissue thickness. The authors also recorded exercises such as cycling, treadmill running and deadlifting completed by astronauts in-flight and post-flight.

One year after flight the median results for 16 of the astronauts showed incomplete recovery of the shinbone. Median shinbone failure load, measuring bone strength, was reduced by 152.0 newtons from 10,579 newtons at pre-flight to 10,427 newtons after one year.