The largest antenna ever tested in ESA's Hertz radio frequency test chamber is this 5-m diameter transponder antenna, which will operate down on the ground to help calibrate the Biomass mission, which will chart all the forests on Earth.

"This is a particularly challenging test campaign both in terms of the size of the antenna and the very low P-band frequency that Biomass will be using, which allows it to pierce through forest canopies to acquire individual trees," explains ESA antenna engineer Luis Rolo, overseeing the test campaign.

"Usually when we test a large satellite here, its antenna is significantly smaller, typically between 0.5 and 2 meters across. But this entire structure is a radiating antenna in its own right, its sides coming near to the chamber walls.

"What this means is that the testing process highlight some aspects of the chamber we've never seen before, even after many years of testing. But we've come up with a measurement method involving multiple acquisitions from different spots within the chamber, combined carefully to subtract such environmental effects, yielding very accurate results.

A NASA-funded team led by SMU researchers think that their small, lightweight device developed to measure spaceship velocity will improve the odds of successful landings on Mars and other planets.

Smaller, they say, is better in space.

The optical microresonator built by the team is only 2 millimeters in length, compared to the velocity-monitoring tool most commonly used on spacecraft—the Fabry-Perot interferometer—which can be as long as 500 millimeters. NASA and other space agencies may be able to use the microresonator to get an accurate, quick measurement of how fast a spaceship is moving in a specific direction.