NASA's Mars 2020 rover looks to be on track with the space agency announcing that the unmanned explorer has gone on to the fourth phase of its development, which includes final system assembly, testing, and launch. The follow up to the highly successful Curiosity rover mission is scheduled for liftoff in the middle of 2020 and arrival at the Red Planet in February 2021 to begin its mission to explore areas that might once have harbored microbial life.

The latest mission in NASA's Mars Exploration Program, Mars 2020's objectives are based on the findings of Curiosity's first four years on the planet. Its primary objective is to visit areas that were once habitable and collect and analyze soil and rock samples for chemical signs of past life. Some of these samples will be stored for recovery and return to Earth by a future mission. In addition, the rover will study the present Martian environment to gage the suitability for supporting a future manned mission.

That Mars 2020 is based on the design of Curiosity is obvious at the first glance. It has the same chassis and undercarriage as Curiosity, though, hopefully, the wheels will get an update after the beating that Curiosity's aluminium treads are suffering. Like Curiosity, it will also use a plutonium-fueled nuclear radiothermal generator as a power source.

Mars 2020 will sport a similar arm and camera mast to Curiosity, but it will include a new suite of seven scientific instruments developed by US and international partners. This includes; a new coring drill with a rack of about 30 sample tubes for future analysis by Earthside laboratories; instruments for studying the chemical, mineral, physical, and organic properties of Mars for signs of past life; high-resolution cameras; three spectroscopes that can study rock and soil at a distance; weather and dust sensors; ground-penetrating radar; and microphones, which will send back the first audio feeds from Mars.

The spacecraft will use the same modular approach as Curiosity for the trip to Mars and it will land using the same skycrane system as Curiosity, but one that's been improved. The Martian atmosphere is so thin and so variable that landers coming in have to hit it at a much lower altitude than on Earth. This makes for very imprecise landings, so NASA has installed a radar range trigger to handle the descent and landing that the space agency says will reduce the landing area by almost half.

In addition, Mars 2020 will take pictures during its descent that the rover will use as maps to identify and avoid unsafe areas as well as zeroing in on sites of interest. Meanwhile, other cameras will send back images of the landing parachute opening, which will help engineers to design better versions in the future.

NASA says that the rapid progress of Mars 2020 is due in part to using so much of Curiosity's design. This allowed the development team to use tested systems and already built components in the three earlier design and fabrication phases.

"The Mars 2020 rover is the first step in a potential multi-mission campaign to return carefully selected and sealed samples of Martian rocks and soil to Earth," says Geoffrey Yoder, acting associate administrator of NASA's Science Mission Directorate. "This mission marks a significant milestone in NASA's Journey to Mars – to determine whether life has ever existed on Mars, and to advance our goal of sending humans to the Red Planet."