There are currently a record seven active unmanned missions operating on or around Mars, but the parade has only just begun. The next few years will be very busy indeed as a new series of international missions head out to the Red Planet, possibly culminating in the first manned landing or even colonization before 2030. Let's have a look at the program.
At the moment, there are seven active Mars missions with one more scheduled to arrive in October 2016. Operated by NASA, ESA, and India's ISRO, six of these are orbiters and two are rovers. That may seem excessive for a planet that makes the Atacama desert look like a garden, but Mars is of great interest to scientists because of its potential for telling us more about the Earth's climate, the origins of the inner planets, and whether life arose in more than one place in the Solar System. Not to mention that getting a spacecraft successfully to Mars wins major points for any spacefaring nation (or business enterprise).
Planned and enroute
Like the current batch, the planned missions and those already on the way are a mixed bag. There are about seven of them scheduled to arrive at Mars after 2020, with "about" being the operative word because budgets and national priorities can change very quickly. These missions are, for the most part, extensions and more focused versions of the current ones, aiming to learn more about the geology and atmosphere of the planet, and seeking evidence to answer the question of whether Mars ever harbored life.
The first of these missions is already more than halfway there. Exobiology Mars (ExoMars) 2016 is a joint ESA/Roscosmos mission in two parts that is tasked with looking for evidence of life on Mars. The first is the Trace Gas Orbiter (TGO), which will look for traces of methane in the Martian atmosphere with an eye on learning more about the mechanism that produces it and to determine if this is geological, chemical, or biological. It will also send back images of the Martian surface and search for subsurface ice deposits.
The second is the Schiaparelli entry, descent, and landing demonstrator module, which is currently docked with the TGO. It's much simpler spacecraft that will be released three days before the TGO arrives in Mars orbit on October 19, 2016. As the TGO goes into an elliptical orbit about the planet, the Schiaparelli module's brief career will entail taking readings of the atmosphere during its descent to the surface. Though it's not a lander, it will test landing radar, navigational cameras, and other instruments that will be used for the ExoMars 2020 lander mission. If it survives the descent, the probe will not be able to send back pictures from the surface, but it will continue to send back telemetry for as long as its batteries hold out.
The next NASA mission is the InSight lander, which is scheduled to lift off from Vandenberg Air Force Base in California on May 5, 2018 (a faulty vacuum seal in one of the primary instruments meant it missed the 2016 launch window). The InSight stationary lander is based on NASA's Phoenix lander, which set down at the Martian North Pole in 2008, and is designed for a 720-day primary mission near the Martian equator.
Insight's primary mission is to study the interior of Mars to learn more about is evolution – especially in regard to the density and structure of its core, mantle, and crust. To do this, it will use robotic arm for placing instruments, including hammering a heat-flow meter up to 15 ft (4.5 m) into the ground. This will be the deepest drilling operation ever carried out on Mars.
Mars 2020 is the temporary name for NASA's next Mars rover mission. Its primary objective is to visit areas that could once have been 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, and the rover will study the present Martian environment to gage the suitability for supporting a future manned mission.
The design of the rover is based heavily on Curiosity with the same chassis and undercarriage as Curiosity, Like Curiosity, it will also use a plutonium-fueled nuclear radiothermal generator as a power source, and it will sport a similar arm and camera mast, but it will also include a new suite of seven scientific instruments developed by US and international partners.
ExoMars 2020 started out as ExoMars 2018, but the follow-on mission for ExoMars 2016 was delayed due to various schedule overruns. Its purpose is to act as an example of Russo-European cooperation as well as a technology demonstrator by landing a rover in the equatorial region of Mars.
Now scheduled to lift off in July 2020, the second ExoMars mission will have a Russian-built landing platform carrying a European-built rover. The landing platform will carry out studies of the Martian atmosphere, radiation, and signs of water. Meanwhile, the rover will hunt for organic molecules and biosignatures, and study the geology using subsurface radar.
The last three planned missions are a bit hazier because they are still in the planning stages. One of these is the Indian Space Research Organisation's (ISRO) Mangalyaan 2 probe, which is a follow up to its successful Mars Orbiter Mission (also known as Mangalyaan 1) that reached the Red Planet in 2014. Aimed to launch in 2020, its current design is to include an orbiter, lander, and rover, which will be built in partnership with France's Centre National d'Etudes Spatiale.
2020 Chinese Mars Mission
Another one on the drawing board is the 2020 Chinese Mars Mission. According to Chinese state media, it will be launched atop a Long March 5 rocket in July or August 2020 and will include an orbiter, lander, and rover – the designs for which were recently unveiled. In addition, it will act as a technology demonstrator for a sample return mission in the 2030s.
Emirates Mars Mission
Then there is the Emirates Mars Mission, also known as the Hope Mars Mission. Also planned for 2020, it will be a hexagonal, solar-powered orbiter built by the United Arab Emirates and will study the Martian atmosphere.
Along with the planned missions, there are more that are little more than proposals, challenge entrants, and back-of-the-envelope ideas that may never get funding. The more serious and likely to go ahead include a sample return mission by NASA or other space agencies to retrieve the samples collected by the Mars 2020 mission and return them to Earth.
Though no details have been approved, NASA has put forward a plan to use rover to pick up the sample cases and transfer them to a lander with an ascent vehicle aboard to send the samples into Mars orbit. There it would rendezvous with a solar-electric spacecraft, which would return to Earth with its cargo for examination.
Other proposed missions include a joint mission by Finland, Russia, and Spain called Mars MetNet to study the Martian weather; Japan's MELOS rover for Martian geology, meteorology, and exobiology, which might include a drone aircraft; NASA's Icebreaker Life, which is a near copy of the Phoenix lander for looking for signs of life on the Martian plains during the local summer; the Phobos And Deimos & Mars Environment (PADME) to survey the Martian moons; ESA's Phootprint, which would return samples from Phobos; and BOLD, which is intended to follow up on the original Viking biology experiments.
What really piques public interest in Mars exploration is the possibility that an astronaut may one day setting foot on the red sands of the planet's dead sea bottoms. Proposals for missions to Mars go back to Wernher Von Braun's The Mars Project in 1953, where he made a detailed plan for a fleet of ten spaceships carrying a crew of 70 that would be assembled in Earth orbit before setting off for Mars in 1965.
Since then, there have been countless proposals for missions to Mars. Some planned to use nuclear-powered rocket engines, others were jumped-up versions of Apollo hardware, and some were so minimal that it would have been like crossing the Atlantic in a dinghy. There were rotating ships to create artificial gravity, electric drive ships that accelerated at a snail's pace to build up tremendous velocities, and some that used complicated orbits to ferry back and forth from Mars to Earth.
Journey to Mars
Today, though every major spacefaring nation expresses interest in sending humans to Mars, the serious contenders are NASA and private companies. The US space agency even talks about its "Journey to Mars" on a regular basis and has set a goal to send a manned mission in the 2030s, but the phrase is still a slogan rather than an official program.
If it does receive funding, the current plan is to hitch the Orion spacecraft to an inflatable habitat to provide the crew with more room for the 16-month journey. Unfortunately, the Space Launch System (SLS) is still under development and the Orion has suffered a number of setbacks, so when and if are still large questions.
A more ambitious project is Mars One. It's privately-funded venture that plans to not only to send an astronaut to Mars, but to colonize it by 2025 with permanent settlers sent on a one-way mission with no chance of return. The idea is that robot landers will seek out a suitable spot for the outpost, then be followed by a series of unmanned cargo landers to supply robots that would build the habitats and support structures. Once everything is set up, the first four colonists would be sent with four more to follow every four years.
The project is supposed to be funded by a reality television series, and it has received a great deal of publicity since it announced in 2012, but the television deal fell through, questions were raised about the technology proposed and the colonist selection process. And then there's the fact that with less than nine years until the first person is set to leave, none of the required hardware has been sorted out.
SpaceX founder Elon Musk has made no bones about wanting to go to Mars – and he means personally. Plans for an unmanned landing in 2018 using a Red Dragon capsule were announced in 2016 and in an interview with the Washington Post the tech entrepreneur gave a broad outline of a proposal that could see a manned mission touching down on the Red Planet in 2025.
The proposed 2018 landing would be the start of an intense program of sending ships to Mars every two years as Earth and Mars come into opposition. The landings would culminate in a manned mission touching down in 2025 using the Mars Colonial Transporter, which is scheduled to first fly in 2022 and is designed to not only carry explorers, but, as it says on the tin, colonists one day.
So the next decade or two on Mars looks very busy, with all manner of robotic probes on their way. This cyber-armada will provide new insights into the nature and history of the Red Planet and may even tell us if it ever was home to life. We may also see the dream of science fiction writers and just plain dreamers come true as the first footprints are made and the first flags planted in the rusty sands. Perhaps future robotic probes sent to Mars will need to be equipped with "please don't touch" signs for the benefit of inquisitive settlers.