A New Design For A Plasma Engine Fuels On Only Thin Air

Choosing what orbit to put a satellite in always comes with trade-offs. When it comes to Very Low Earth Orbit (VLEO), between 100-450 km, there are distinct advantages. Remote sensing cameras can take better pictures, comms and radar require less power, and atmospheric drag will automatically clean up dead satellites. But there’s also a cost - air friction requires any satellite in this orbit to use an engine near constantly to stay in orbit, which in turn requires fuel - typically in the form of expensive gases like Xenon. So, as part of his PhD thesis at the University of Stuttgart, which is available in arXiv, Francesco Romano decided to solve that problem by using the very air molecules that cause that friction as fuel for a plasma engine to keep satellites aloft indefinitely in VLEO.

Venus Moon Would Have Been Doomed From The Start, Says New Paper

Venus likely never had a moon and even if it did, it would have soon been torn asunder by the planet’s own gravity, says prominent planetary astrophysicist.

Dense Galaxies Are Carving Out A Bubble in the Early Universe

Light could only travel freely in the Universe after cosmic reionization. Before that, neutral hydrogen stopped photons from travelling. The JWST has found evidence of an overdensity of galaxies carving out a bubble of reionization. Is this how it all started?

What's Carving Active Gullies on Mars? It's Not Water

Scientists were shocked when they received the first images of Martian gullies. They were even more shocked as those gullies appeared to change over time. Their similarities to gullies seen on Earth were uncanny, but all of Earth’s gullies are formed by the water run-off, and Martian is too cold and has too sparse an atmosphere to have liquid water on its surface. Whatever has been causing those changing gullies couldn’t have been water, so what was it? A new paper from Apolline Leclef of the Institut d’Astrophysique Spatiale at Université Paris-Saclay and her colleagues, available in pre-print on arXiv, shows how they are likely caused by CO2 frost turning into a fluid.

NASA's Next Great Observatory Could Spot Oceans on Distant Worlds

We’ve found over 5,500 exoplanets so far. Dozens of them have been in the habitable zone of their parent stars, where, at least in theory, they could host an ocean. But we’ve never definitively found a liquid ocean on another planet. A new paper from researchers Eleanor Cornish and Tyler Robinson of the University of Arizona, available in pre-print on arXiv and submitted to the Astrophysical Journal, looks at a unique way we might be able to find one - by looking for its “glint”.

eROSITA's Second Data Release Catalog Delivering the Most Comprehensive High-Energy Census of the Cosmos to Date

The eROSITA Consortium has issued the survey's second data release (DR2), nearly doubling the previously known eROSITA X-ray sources to two million.

Unexplained Gamma-Rays from the Galactic Center Could be from Self-Annihilating Dark Matter

Over a decade ago, the Fermi satellite detected an excess of gamma-ray emissions in the galactic center. Potential explanations included Sgr. A*, the Milky Way's SMBH, pulsars, and even self-annihilating dark matter. There's no clear answer yet, since the region is so difficult to observe. But recent research shows that dark matter can't be ruled out.