After a series of delays, SpaceX is set to launch four astronauts to the International Space Station on Wednesday night on the "Crew-3" mission.

The orbital outpost is currently operating with just one NASA astronaut in the US segment to welcome the incoming crew, after the astronauts of the earlier Crew-2 mission splashed down in the Gulf of Mexico on Sunday night.

Crew-3's Raja Chari, Kayla Barron and Tom Marshburn of the United States and Matthias Maurer of Germany are now set to launch aboard a Crew Dragon capsule fixed to a Falcon 9 rocket at 9:03 pm local time (0203 GMT Thursday) from the Kennedy Space Center in Florida.

An international team of space researchers has learned more about the density of the Martian surface by analyzing data from the Mars InSight lander that was received during Perseverance's descent. In their paper published in the journal Nature Astronomy, the group describes their study of seismic data from InSight as Perseverance dropped heavy blocks during its descent.

One of the ways that planetary scientists learn more about the makeup of other planets is by studying seismic activity—waves from such activity can provide clues to the density of different parts of a planet. In this new effort, the researchers noted that gathering seismic data from extraterrestrial events such as asteroids striking the surface of a planet is difficult as they are so random. But they also noted that the Perseverance mission offered a unique opportunity—as part of its descent earlier this year, the rover's landing craft dropped two tungsten blocks—each weighing approximately 77.5kg to the surface below.

Short for Venus Mass Spectrometer, VMS is one of five instruments aboard the DAVINCI descent probe.

Ultra-hot Jupiters—named as such because of their physical similarities to the planet Jupiter—are exoplanets that orbit stars other than the sun with temperatures so high that the molecules in their atmospheres are completely torn apart. They are among the most extreme environments in our galaxy.

They also whip around their parent stars in orbits that only last a few days, and astronomers still aren't sure how it's possible for them to form.

While these harsh conditions might sound like they're as extreme as it gets, astronomers are starting to realize they may just be the tip of the (very hot) iceberg. In a recent study published in The Astrophysical Journal Letters, my colleagues and I discovered that one of these exotic worlds in particular is even more extreme than we'd ever thought.