An interplanetary conga line has begun to arrive at the famous red planet, Mars.
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Way back in July last year, three different countries launched missions to one of our neighbour planets.
Launching around the same time wasn't a coincidence, they needed the planets to (almost literally) align.
Earth goes around the Sun (a year) quicker than Mars does. While our year is 365 days, it takes Mars 687 days. This is probably not surprising given Mars is further away from the Sun.
As a consequence though, sometimes Earth and Mars are on the same side of the Sun and closer together, and sometimes we are on opposite sides and far apart.
Just think about cars of different speeds going around the race track. Sometimes they are near each other and sometimes they are on opposite sides of the track.
About every 26 months, Mars and Earth end up on the same side of the Sun and are at their closest point to each other.
One of the main goals is to search for underground water which will aid future human exploration.
This last happened back in early October and will next happen in December 2022.
But if the close approach was in October, why launch in July? With our current technology, it takes about six to seven months for the missions to reach Mars. By leaving about three months before the close approach of Mars, your six-month travel time is optimised to minimise the distance. If they launched in October, the six-month trip would be longer as Earth and Mars drift farther and farther apart.
The United Arab Emirates' Hope mission was the first to arrive. Hope entered Martian orbit on February 10 (Australia time). Upon reaching Mars, the probe flew on autopilot as it got itself into a nice orbit. It takes over 10 minutes for signals to reach Earth from the probe, which is quite a considerable lag, so they can't control it in real-time.
Over the next few years, Hope will be doing detailed monitoring of the Martian atmosphere, giving us a complete picture of Mars.
The day after, China's first rover, Tianwen-1, reached Mars.
It used its thrusters to get into an orbit around the planet.
After a few months in orbit, most likely sometime in May, it will attempt to land the rover on the planet's surface.
One of the main goals is to search for underground water which will aid future human exploration.
This Friday, February 19, just before 8am AEDT, NASA's latest rover, Perseverance, will be touching down on the red planet.
Similar in size and shape to NASA's Curiosity rover which is currently on Mars, Perseverance is fitted out with new instruments, some of which will look for signs of ancient microbial life on Mars. Yes, it is tasked to look for signs of life.
Attached to Perseverance is NASA's Ingenuity - a helicopter for Mars. The goal of Ingenuity is to test the ability to fly on Mars.
As the environment of Mars is very different than on Earth, including a weaker atmosphere and greater temperature extremes, it is not straightforward.
If successful, there might be a whole new way to explore Mars.
Mars is going to be the place to be!
- Brad Tucker is an astrophysicist and cosmologist at Mount Stromlo Observatory, and the National Centre for the Public Awareness of Science at ANU.
