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CAPE CANAVERAL — America’s next Mars rover, a $2.1 billion nuclear-powered vehicle to search for evidence that life once existed there, will be launched to the Red Planet in the summer of 2020 by a powerful Atlas 5 rocket.

Jim Green, planetary science division director, revealed the selection of the United Launch Alliance vehicle at the NASA Advisory Council meeting in Cleveland this afternoon.

“It will be the Atlas 5 carrying Mars 2020 to Mars,” Green said.

ULA’s Atlas 5 and Delta 4-Heavy and SpaceX’s Falcon Heavy were studied as possible launch vehicles for the intermediate-to-heavy classed payload. It was not immediately known if SpaceX submitted a bid for this launch contract.

But, currently, Atlas 5 is the only launch vehicle that holds a NASA certification for launching the nuclear batteries made of plutonium that will power the 2,000-pound rover.

The six-wheeled robot will use by a Multi-Mission Radioisotope Thermoelectric Generator, enabling surface operations day and night by converting heat into electricity.

Atlas 5 has successfully performed the only launches of nuclear-equipped spacecraft for NASA in recent history: New Horizons to Pluto in 2006 and the Mars Science Laboratory’s Curiosity rover in 2011.

The Mars 2020 mission will search for indications of past Martian life, building upon the ongoing field geology work by the Curiosity rover that shows the planet’s early history had conditions suitable for life.

“The central scientific objective is seeking the signs of life,” said Ken Farley, the Mars 2020 project scientist.

“Did life evolve there? Did it thrive there? Now, this life almost certainly disappeared because the climate changed about 3.5 billion years ago…So we are going to focus our exploration on the distant past.”

The new mission now under development will send a Curiosity-like vehicle to an area of Mars likely to have once been habitable, exploring for a full Martian year — nearly 700 days — and collecting a cache of soil and rock samples for a future return to Earth.

“(We will be) preparing a very compelling set of scientific samples and leave them on the surface of Mars for a possible future mission to go and get them,” Farley said.

A suite of science instruments include a stereoscopic camera package, a camera for the detection of organic compounds in rocks, an X-ray fluorescence spectrometer for elemental composition data, an ultraviolet laser for mineralogy, an experiment to produce oxygen from atmospheric carbon dioxide, a ground-penetrating radar to probe the geologic subsurface and a mini weather station.

And there will be microphones on the landing system and rover to pick up the sounds of Mars.

Mars 2020 will use the combination of a heat shield, supersonic parachute, rocket engines and “sky crane” landing technique successfully employed by Curiosity in its touchdown on Aug. 6, 2012.

“From the outside, things look pretty much the same,” said Allen Chen, the Mars 2020 entry, descent and landing (EDL) lead at JPL.

“But under the hood we’ve made a number of improvements…that allow us to shrink the area we could be coming down in — the landing ellipse — by about 50 percent. That allows us to land in much tighter spots, spots we could not have considered before with Curiosity, and lets us land closer to the types of things that the scientists want to go see.”

What’s more, the descending craft will take images of the ground below to autonomously compare with an onboard map to avoid hazardous terrain.

“We were always looking for flat, boring landing strips. Now we can look for places that have patches of flat along with science targets nearby,” Chen said.

Some of the candidate landing locations now being studied for the Mars 2020 rover were sites rejected for Curiosity because they were deemed unsafe.

“Now we can consider landing in those,” Chen said.

Launch from Cape Canaveral is scheduled for July 2020 when the planetary alignment between Earth and Mars offers a brief window to dispatch the rover. It will arrive at the Red Planet for entry, descent and landing in February 2021 at a site still to be chosen.

“The most important decision ahead of us is where we are going to send the rover,” Farley said.

The science team has narrowed the list of potential landing sites to 8 possibilities.

“Those sites all have characteristics that we believe suggest that they were habitable. The first half of the sites are associated with surface water — rivers, lakes and deltas — recorded in the rocks. The other half of the sites are associated with high-temperature water circulating through rocks. In those two kinds of environments on Earth, those are areas microbial life thrives,” Farley said.

NASA also plans to launch a batch of Cubesats to Mars alongside the 2020 rover. Selections of which projects will fly have not been made.

The 197-foot-tall, 1.2-million-pound rocket will be powered off the launch pad by its RD-180 kerosene main engine and four solid-fuel boosters. The Centaur upper stage will sport an RL10C cryogenic engine and shrouded by an 18-foot-diameter nose cone.

The current era of Mars exploration dates back to 1996 and the launch of the Mars Global Surveyor orbiter and Mars Pathfinder lander with the tiny Sojourner rover. Mars Odyssey launched in 2001 after an orbiter and lander duo was lost in 1999.

The plucky Spirit and Opportunity rovers launched separately in 2003, the Mars Reconnaissance Orbiter followed in 2005 and the stationary Phoenix lander went in 2007.

Curiosity left Earth in 2011 and the MAVEN atmospheric orbiter launched in 2013.

Atlas 5 rockets launched MRO, Curiosity and MAVEN, and the Mars 2020 rover joins InSight on the booster’s future manifest. All of the others were entrusted to the smaller Delta 2 rocket.

InSight is the scheduled 2018 flight of a seismic lander that will drill into the reddish ground to study how terrestrial planets form.

The Atlas 5 has become a NASA workhorse, flying 12 missions to date with 7 more currently scheduled by the agency’s Launch Services Program through 2020, including OSIRIS-REx, GOES R and S, TDRS M, Solar Orbiter and the two Mars launches.

The vehicle also plans to launch NASA astronauts to the International Space Station in the Starliner capsules starting in 2018 and boost to orbit the Dream Chaser cargo-delivery mini shuttle starting in 2019.

In its 63 previous missions since debuting in August 2002, the Atlas 5 has flown 25 flights dedicated to the Defense Department, 14 commercial missions, 12 for NASA and 12 for the National Reconnaissance Office.

Our Atlas archive.