Future missions to the moon and Mars must address many challenges, including preventing loss of bone and muscle tissue in astronauts. Research on the International Space Station is helping to address this challenge.

Without Earth's gravity, both bone and muscle atrophy, or become smaller and weaker. Early on, scientists realized that exercise is a critical part of maintaining healthy bones and muscles in space, just as it is on Earth. From simple elastic bands on early missions, exercise hardware has become increasingly advanced. Current equipment includes the Advanced Resistive Exercise Device (ARED) weight-lifting system, a second generation-treadmill called T2, and the Cycle Ergometer with Vibration Isolation and Stabilization System (CEVIS) cycling machine. Studies continue to refine this equipment as well as the intensity and duration of how astronauts use it, with crew members now averaging two hours of exercise per day.

Installed in 2008, ARED uses a piston and flywheel system to provide loading that essentially mimics weightlifting in weightlessness.

New data analysis indicates that NASA and its partners could have more cost-effective methods for dealing with the growing issue of orbital debris than previously thought.

A new report from NASA's Office of Technology, Policy, and Strategy provides agency leadership with new insight about how to measure the risks presented by orbital debris.

"Growing activity in Earth's orbit has brought us everything from faster terrestrial communications to a better understanding of our changing climate," said Charity Weeden, who leads NASA's OTPS. "These blossoming opportunities are resulting in a more crowded space environment. This study is part of NASA's work to rapidly improve our understanding of that environment as outlined in NASA's recently released Space Sustainability Strategy, by applying an economic lens to this critical issue.

NASA and Boeing need more time to make sure a helium leak on its CST-100 Starliner is low enough risk to send humans into space.

So the launch of NASA astronauts Butch Wilmore and Suni Williams has now been pushed to May 25 targeting a 3:09 p.m. liftoff atop a United Launch Alliance Atlas V rocket from Cape Canaveral Space Force Station's Space Launch Complex 41.

The duo were sitting in the capsule on the pad with about two hours left on the countdown clock on May 6 when a problem with a fluttering valve on the upper stage of the Atlas V forced mission managers to scrub.

After rolling the rocket back to ULA's Vertical Integration Facility near the pad and switching out the valve, managers found a second issue with a small helium leak on the Starliner's service module.

The source of the leak was traced to a flange on a reaction control thruster, and teams performed pressure tests that showed the leak was "stable and would not pose a risk at that level during the flight," according to a NASA press release.