For decades, space and ground telescopes have provided us with spectacular images of galaxies. These building blocks of the universe usually contain several million to over a trillion stars and can range in size from a few thousand to several hundred thousand light-years across.

After a nearly seven-month journey to Mars, NASA's Perseverance rover is slated to land at the Red Planet's Jezero Crater Feb.

How times have changed since the Apollo era. Within the space of a few days, two space missions from China and the United Arab Emirates (UAE), respectively, are set to reach Mars. The UAE's Hope mission will go into orbit around Mars on February 9. The next day, the Chinese Tianwen-1 mission – an orbiter and lander—will swing into orbit, with a predicted landing date sometime in May.

It is a very big moment for both countries. Hope is the first interplanetary mission by an Arab nation ever. And if China succeeds, it will be the first country ever to visit and land on Mars on its first try. The odds are stacked against them with nearly 50% of all Mars missions failing. China already lost a Mars orbiter mission (Yinghuo-1) back in 2011.

But before the missions can start doing science, tense moments await. As they arrive at the planet, they need to trigger a burn of their engines just at the right time to slow the probes down so they can be captured by Mars' gravitational field. Given the large distance from Earth, this needs to be carried out automatically by the probe.

Tianwen-1

If all goes well, the orbiter Tianwen, which means "Questions to Heaven" and the yet unnamed rover will attempt to measure Mars's climate and "ionosphere", a layer of electrically charged particles surrounding the planet.