WASHINGTON — The missile defense portion of a 2013 spending bill signed into law March 26 by U.S. President Barack Obama includes significant funds for a space-based missile tracking system that has struggled to win congressional approval in past years.

The defense measure, part of a larger spending package designed to stave off a government shutdown that otherwise would have occurred at the end of March, also includes sufficient funding to complete testing of a system developed jointly with Germany and Italy. Congress previously sought to terminate the program, known as the Medium Extended Air Defense System.

All of the programs funded in the budget would be subject to the automatic, across-the-board budget cuts known as sequestration. The Department of Defense Appropriations Act of 2013 funded most agencies at 2012 levels but gave the Pentagon a tailored budget for the remainder of fiscal year 2013, which runs through Sept. 30.

Notably, the bill funds the Precision Tracking Space System (PTSS), a proposed constellation of satellites that would track ballistic missiles during the midcourse portion of the flight. In 2012, Congress allocated $80.7 million for the program despite a report that questioned the expense. That report, from the National Research Council, said the Defense Department could use the Space Based Infrared System missile warning satellites and X-band radars on the ground to perform the same mission at a lower cost.

Officials with the U.S. Missile Defense Agency (MDA) have said PTSS is the only “technology available” to provide persistent tracking of missiles globally.

For 2013, the MDA requested $297 million for the PTSS program; Congress responded with $242 million in the conference bill sent to the president’s desk March 21.

The MDA will rely on the Johns Hopkins University’s Applied Physics Laboratory in Laurel, Md., to develop two PTSS prototype satellites, with a first launch targeted for 2015. An industry team is expected to be chosen in 2014 to build between nine and 12 operational spacecraft planned to begin launching in 2018.

The funding measure also slows development of a new interceptor known as Standard Missile-3 Block 2B. Congress has long been reluctant to fund the interceptor, which was slated for deployment in Poland next decade to augment the U.S. territorial shield. But studies have questioned its effectiveness in that role, and the Pentagon in March announced plans to scale back the program to bolster the existing U.S. territorial shield featuring interceptors in Alaska and California.

The MDA had requested $224 million for the program, but Congress shrunk that figure to $61 million. Lawmakers transferred $50 million of the resulting savings to another interceptor program, the Standard Missile-3 Block 2A.

The 2013 appropriation calls for $380 million for the AN/TPY-2 missile-detection radar, up from $217 million the MDA requested. That includes $163 million for an additional radar.

In September, then-U.S. Defense Secretary Leon Panetta announced that the United States and Japan would install an additional AN/TPY-2 X-band missile tracking radar on Japanese territory as part of expanded missile defense ties between the two countries. The radar system, built by Raytheon Co. of Waltham, Mass., will bolster the protection of Japanese and U.S. territory against the North Korean missile threat.

Congress also set aside $380 million for a trilateral anti-missile program known as Medium Extended Air Defense System in this year’s plan. The money can be used to complete the development and test program with Germany and Italy or pay the fines to terminate the contract, but the White House has made clear its intention to complete the test phase. Some legislators have argued it is not worth the expense to test a system the Pentagon has no plans to buy.

Combined, the three countries have spent about $4 billion on the project.

Mike Gruss is a senior staff writer for SpaceNews. He joined the publication in January 2013 to cover military space. Previously, he worked as a reporter and columnist for The Virginian-Pilot in Norfolk, Va. and The Journal Gazette in Fort Wayne, Ind. He...