Nebula Public Library

We report on a new test of the gravitational redshift and thus of local position invariance, an integral part of the Einstein equivalence principle, which is the foundation of general relativity and all metric theories of gravitation. We use data spanning 1008 days from two satellites of Galileo, Europe’s global satellite navigation system (GNSS), which were launched in 2014, but accidentally delivered into elliptic rather than circular orbits. The resulting modulation of the gravitational redshift of the onboard atomic clocks allows the determination of redshift with high accuracy.

The purpose of this study was to define the a communication subsystem architecture (including both ground and space segments, as well as operational methods) that allows robust RF TT&C links during superior solar conjunction phases. The defined architecture shall ensure robust and reliable links in scintillation regimes (i.e. at low SEP angles) where TT&C links are nowadays degraded, leading to occasional link interruptions. Similarly, the defined architecture shall ensure that at even higher scintillation regimes (i.e.

There is an increasing need for ever smaller pulse-tube coolers. These coolers have the characteristics necessary for space applications because the absence of moving parts in the cold finger makes them extremely reliable and any induced vibrations are typically smaller and easier to control.

But these types of cooler are less efficient and have a lower power density. Typically, this is resolved by increasing their drive frequency, to reduce amplitudes and displacements, which means that the coolers are smaller

The International Space Station (ISS) is slowly approaching the end of its mission. The European Space Agency (ESA) and its international partners are considering new mission targets for the future of human space exploration in the post-ISS era. Highest ranked on the list of potential targets are a return to the Moon, Near-Earth Objects or asteroids, the moons of Mars (Phobos, Deimos) and, as the ultimate target, the surface of Mars.