China's "Zhurong" rover, part of its ambitious space programme to send a probe to Mars, is set to attempt the challenging landing on the Red Planet in the next five days, Beijing's space agency said Friday.

The tricky touchdown, if successful, would come a few months behind America's latest probe to Mars, as Beijing presses ahead with its increasingly bold space ambitions.

"Based on current flight conditions, the Tianwen-1 probe intends to choose an opportunity to land ... in the period from early morning Saturday to Wednesday Beijing time," the China National Space Administration said in an online statement.

If asked where meteorites come from, you might reply "from comets." But according to our new research, which tracked hundreds of fireballs on their journey through the Australian skies, you would be wrong.

In fact, it is very likely that all meteorites—space rocks that make it all the way to Earth—come not from icy comets but from rocky asteroids. Our new study found that even those meteorites with trajectories that look like they arrived from much farther afield are in fact from asteroids that simply got knocked into strange orbits.

China launched Tianhe-1, the first and main module of a permanent orbiting space station called Tiangong (Heavenly Palace 天 宫), on April 29. Two additional science modules (Wentian and Mengtian) will follow in 2022 in a series of missions that will complete the station and allow it to start operations.

While the station is not China's first—the country has already launched two—the modular design is new. It replicates the International Space Station (ISS), from which China was excluded.

There are many reasons for China to invest in this costly and technologically challenging project. One is to conduct scientific research and make medical, environmental and technological discoveries. But there are also other possible motivations, such as commercial gains and prestige.

That said, Tiangong does not aim to compete with the ISS. The Chinese station will be smaller and similar in design and size to the former Soviet Mir space station, meaning it will have limited capacity for astronauts (three versus six on ISS).

When a massive star dies, first there is a supernova explosion.

The Gaia spacecraft is an impressive feat of engineering. Its primary mission is to map the position and motion of more than a billion stars in our galaxy, creating the most comprehensive map of the Milky Way thus far. Gaia collects such a large amount of precision data that it can make discoveries well beyond its main mission. For example, by looking at the spectra of stars, astronomers can measure the mass of individual stars to within 25% accuracy. From the motion of stars, astronomers can measure the distribution of dark matter in the Milky Way. Gaia can also discover exoplanets when they pass in front of a star. But one of the more surprising uses is that Gaia could help us detect cosmic gravitational waves.

A new study shows how this can be done. The work is based on an earlier study done using very long baseline interferometry (VLBI), whereby radio telescopes measure the position and apparent motion of quasars. Quasars are bright radio sources billions of light-years away. Because quasars are so far away, they act like fixed points in the sky.