Two companies, OneWeb and SpaceX, are racing to put fleets of thousands of communication satellites into orbit. In March, they had their first near miss. Avoidance maneuvers were successful, but how many more close calls will they face in the future?

SpaceX has already launched over a thousand of its Starlink global broadband internet satellites, and competitor OneWeb has lofted 146 of its own. Both companies—and several others—are actively prepping for dozens of more launches and thousands of more satellites.

But while space is a big place, orbits are a precious resource, especially with so many satellites already up and so many more planned. near misses are unavoidable, as both companies found out on March 30th, when they received several "red alerts" from the US Space Force's 18th Space Control Squadron, warning of a possible collision.

The red alert came just five days after OneWeb launched 36 satellites from Russia. While the OneWeb constellation orbits at a higher altitude than Starlink, they must pass through those orbits to get to their operational location.

Since the launch of Sputnik, the Earth's first artificial satellite, in 1957, more than 41,500 tons of manmade objects have been placed in orbit around the sun, the Earth, and other planetary bodies. Since that time, the majority of objects, such as rocket bodies and large pieces of space debris, re-entered the Earth's atmosphere in an uncontrolled way, posing a potential hazard to people and infrastructure. Predicting the re-entry date and time is a challenging task, as one needs to specify the density of the upper Earth atmosphere that strongly depends on solar activity which, in turn, is hard to predict. Earth atmosphere can become very heated due to solar activity which causes it to expand, and a satellite can decay in its orbit and fall back to the Earth due to the effect known as atmospheric drag.

For the last time while it is on Earth, the world's largest and most powerful space science telescope opened its iconic primary mirror. This event marked a key milestone in preparing the observatory for launch later this year.

As part of the NASA's James Webb Space Telescope's final tests, the 6.5-meter (21-foot, 4-inch) mirror was commanded to fully expand and lock itself into place, just like it would in space.

Researchers from the University of Tsukuba have sent mice into space to explore effects of spaceflight and reduced gravity on muscle atrophy, or wasting, at the molecular level.

Gravity is a constant force on Earth, which all living creatures have evolved to rely on and adapt to. Space exploration has brought about many scientific and technological advances, yet manned spaceflights come at a cost to astronauts, including reduced skeletal muscle mass and strength.

Conventional studies investigating the effects of reduced gravity on muscle mass and function have used a ground control group that is not directly comparable to the space experimental group. Researchers from the University of Tsukuba set out to explore the effects of gravity in mice subjected to the same housing conditions, including those experienced during launch and landing. "In humans, spaceflight causes muscle atrophy and can lead to serious medical problems after return to Earth," says senior author Professor Satoru Takahashi. "This study was designed based on the critical need to understand the molecular mechanisms through which muscle atrophy occurs in conditions of microgravity and artificial gravity.