WASHINGTON — Even though NASA’s Earth science budget is slated to rise next year, the U.S. space agency has been ordered by the White House to shelve a pair of big-ticket climate change missions that just last year were planned for launch by 2017.

With U.S. President Barack Obama under pressure to rein in federal spending, the White House eliminated funding for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) and Deformation, Ecosystem Structure and Dynamics of Ice (DESDynI) missions, Steve Volz, associate director for flight programs at NASA’s Earth Science Division, said in a Feb. 24 interview.

The multiyear budget plan NASA sent Congress a year ago called for spending $1.2 billion between 2012 and 2015 to develop CLARREO and DESDynI, two of the four top-tier missions recommended by the National Research Council’s 2007 Earth Science decadal survey. But the White House Office of Management and Budget specifically removed these funds from the agency’s  2012 budget request, Volz said in an interview.

“Removal of these missions was not what we desired and not what the administration desired, but it was a clear recognition and acknowledgement of the budget issues we face as a nation,” Volz said. “It’s cleaner to be allowed to delete the scope that goes along with the dollars than to have to figure out how to do more with less.”

The other two top-tier Earth science missions — Soil Moisture Active-Passive and ICESat-2 — remain budgeted for launch in 2014 and 2016, respectively.

While NASA’s Earth Science Division fared better in the president’s 2012 budget proposal than other parts of the agency, the division stands to receive some $1.7 billion less between 2010 and 2015 than forecast just last year.

That spending plan, which called for giving Earth science a growing share of a NASA budget expected to surpass $20 billion within four years, included enough funding to build and launch all four top-tier decadal survey missions by the end of 2017.

The NASA budget plan unveiled Feb. 14 puts last year’s growth plans on hold. The agency’s overall spending would be frozen at $18.7 billion, and Earth science, after receiving a $400 million boost for 2012, would remain flat at $1.8 billion through at least 2016.

Adding to NASA’s budget woes, the president’s 2011 budget was never enacted, leaving the agency and the rest of the federal government funded at typically lower 2010 levels under stopgap spending measures, the latest of which expires March 4.

Richard Anthes, president of the Boulder, Colo.-based University Corporation for Atmospheric Research and a co-chairman of the committee that produced the Earth science decadal survey, said he was disappointed to learn CLARREO and DESDynI have been indefinitely deferred.

But he said tabling the two missions  is  preferable to requiring every Earth science mission to make due with less.

“They’ve decided to basically reduce the funding greatly to these two missions and put them on the side of the road,” Anthes said in a Feb. 25 interview. “I think that strategy at least makes sense. If you don’t have enough money to do everything, cancel some of them or put some of them on indefinite hold and continue making good progress on the others.”

When NASA chose the Hampton, Va.-based Langley Research Center in late 2009 to manage CLARREO, agency officials tentatively estimated the cost of the mission at $600 million to $800 million. The four-satellite constellation, as envisioned, would collect extremely precise data on emitted and reflected energy in order to study long-term changes in the Earth’s climate. The first two CLARREO satellites would launch aboard a single rocket in 2018 followed two years later by two more satellites, according to a Jan. 21 mission overview posted on Langley’s website. Volz said that although NASA will not fund development of the satellites at least for the next five years, it will continue to study alternatives, such as international partnerships, for obtaining this data.

“We were directed to not go into development or formulation for CLARREO and to eliminate from our developmental timeline the CLARREO mission,” he said. “The guidelines are to continue to study the measurements but not the CLARREO mission.”

DESDynI, the Earth-imaging radar and lidar satellite mission assigned to NASA’s Jet Propulsion Laboratory in Pasadena, Calif., was expected to cost $1.6 billion to build and operate, a cost deemed unaffordable given NASA’s flat budget projections. NASA was told to go back to the drawing board to find a more affordable approach to the mission, one that would have NASA develop the radar element and another nation develop the lidar element, Volz said. But the start of a new development effort would have to be paid for with money not allocated for the other 14 Earth science missions NASA plans to launch by the end of the decade, he said.

“We have on our own put in $2 million a year each for DESDyni and CLARREO to understand how to achieve the overall Earth system science objectives,” Volz said. “Those funds will help us do those studies to determine an affordable option for another radar mission.”