WASHINGTON — Prime contractor Lockheed Martin Space Systems has started assembling the InSight lander that will carry a pair of European science instruments to the surface of Mars for a two-year seismology mission scheduled to launch in 2016, the Denver-based company said in a Nov. 17 press release.

InSight, led by the Jet Propulsion Laboratory in Pasadena, California, is the 12th in NASA’s Discovery series of small, competitively selected, cost-capped science missions. NASA picked the lander in August 2012 over the Comet Hopper and Titan Maritime Explorer missions, the novel designs of which the agency deemed too risky to gamble on with its budget trending flat.

Spacecraft integration will last about six months, Lockheed Martin said in its press release. InSight’s two European instruments are scheduled to arrive within that time frame and start environmental tests this coming summer in Denver, NASA spokesman Guy Webster said in a Nov. 19 email.

InSight is based heavily on the Lockheed-built Mars Phoenix lander that launched in 2007, landed in 2008 and went silent after about five months of surface operations — two months more than called for in its primary mission.

Development of InSight began in December 2013, when the agency committed to a cost of $381.9 million, excluding launch. The estimate places InSight well within its development cost cap of $425 million in 2010 dollars. Tack on another $159.9 million for launch, and the total bill for the mission rises to $541.8 million, according to documents accompanying NASA’s 2015 budget request.

InSight is slated to launch aboard a United Launch Alliance Atlas 5 rocket from Vandenberg Air Force Base in California March 8, 2016, in what will be NASA’s first Mars mission to launch from anywhere other than Cape Canaveral Air Force Station in Florida. The lander is slated to touch down near the martian equator in a region known as Elysium Planitia on Sept. 20, 2016.

Once InSight separates from its rocket, a Lockheed Martin team at the company’s Mission Support Area in Waterton Canyon, Colorado, will take over spacecraft operations. InSight’s roughly two-year primary seismology mission begins when the lander reaches the surface. The data could help scientists understand how small, rocky planets like Mars and Earth form.

InSight could be the last in the Discovery line with a predominantly international instrument suite. Beginning with the 13th Discovery competition, underway since Nov. 5 with a winner to be announced around September 2015, international contributions to a Discovery mission’s instrument package may not exceed one-third of the mission’s total instrument budget.

Even one of InSight’s two primary instruments easily exceeds that limit. For example, the Seismic Experiment for Interior Structures, provided by the French space agency, CNES, cost about $42 million; NASA’s financial contribution to InSight’s instrument suite — a sensor that tracks Mars’ rotational axis, a robotic arm to move the European instruments from the spacecraft to the ground, and two black-and-white cameras — totals only $18 million, according to the 2015 budget request.

InSight’s other main instrument is the German-built Heat Flow and Physical Properties Package, a small drilling rig based on the Multi-Purpose Sensors for Surface and Subsurface Science package that landed on Comet 67P Nov. 12 as part of the European Space Agency’s Rosetta mission. DLR’s InSight instrument will cost about 15 million euros, or just under $19 million, Tilman Spohn, head of DLR’s Institute for Planetary Research in Berlin, said in a Nov. 19 email.

NASA’s rationale for barring significant international contributions to Discovery missions is to avoid footing the bill for getting non-U.S. instruments to distant planets.

“The intent is to not have U.S. spacecraft flying with non-U.S. instruments and mostly non-U.S. science teams,” Michael Lew, lead Discovery program scientist, told the NASA-chartered Small Bodies Advisory Group in July.

NASA spokesman Dwayne Brown did not reply to a request for comment Nov. 18 about whether NASA’s new policy was now a permanent fixture in the Discovery program.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.