U.S. geoscientists are accustomed to being used as a punching bag by climate change skeptics in Congress, who challenge the science of global warming. But some influential Republican legislators are now going a step further, by denigrating the discipline itself.

Senator Ted Cruz (R–TX), the new chair of the science and space panel within the Senate commerce committee and an unofficial presidential candidate, asserted yesterday at a hearing that the earth sciences are not “hard science.” Freshman Senator Cory Gardner (R–CO), a member of the panel and a rising star within the Republican Party, echoed Cruz’s words. And the new chair of an important science spending panel in the House of Representatives, Representative John Culberson (R–TX), has said repeatedly in recent weeks that the earth sciences don’t meet his definition of “the pure sciences.”

“We’ve seen a disproportionate increase in the amount of federal funds going to the earth sciences program at the expense of funding for exploration and space operations, planetary sciences, heliophysics, and astrophysics, which I believe are all rooted in exploration and should be central to NASA’s core mission,” Cruz said at yesterday’s hearing on NASA’s 2016 budget request. “We need to get back to the hard sciences, to manned space exploration, and to the innovation that has been integral to NASA.”

The idea that the geosciences aren’t hard science comes as a shock to Margaret Leinen, president of the American Geophysical Union (AGU) and a former head of the National Science Foundation’s geosciences directorate. “Of course the geosciences are part of the hard sciences,” says Leinen, head of the Scripps Institution of Oceanography and vice chancellor for marine sciences at the University of California, San Diego. “They provide us with very fundamental knowledge about the way the planet works, knowledge grounded in the physical sciences.”

Leinen easily ticks off a host of areas, from analyzing the complex mixtures of physical processes and chemical reactions in the atmosphere and the ocean to characterizing earthquakes, in which geoscientists have made important contributions to physics and chemistry. Geosciences can also be computationally intensive, she says, noting that for many years the world’s most powerful computer was Japan’s so-called Earth Simulator. Modeling future earthquakes in California, for example, requires “some of the most challenging computer simulations in the world,” she adds.

She also scoffs at the attempt to decouple the earth sciences from planetary sciences, a discipline Cruz and Culberson strongly favor. “Our entire exploration of Mars is based on analogies with the Earth,” she points out. That’s also true, she says, for the search for extraterrestrial life on water-rich planets and moons, a burning passion for Culberson.

Universities have long recognized that connection, she points out. “Virtually all academic planetary scientists are in earth science departments, because the Earth, after all, is a planet,” she says.

The 60,000-member AGU reinforced Leinen’s message today in a letter to Cruz. “Earth sciences are a fundamental part of science,” writes CEO Christine McEntee. “They constitute hard sciences that help us understand the world we live in and provide a basis for knowledge and understanding of natural hazards, weather forecasting, air quality, and water availability, among other concerns.”

Cruz’s dissing of the discipline during yesterday’s hearing was part of a broader attack on NASA’s priorities. He presented a chart of spending trends since the start of the Obama administration that purported to show a tilt toward the geosciences and a loss of funding for exploration.

NASA Administrator Charles Bolden, the sole witness, said that he thought the numbers were misleading. “There’s a lot of chartmanship that can go on about what is included,” Bolden told Cruz at one point. “I am not saying that I agree with your numbers.” Senator Gary Peters (D–MI) took a more partisan stance. He quoted from a 2012 National Academies report that noted the “disastrous consequences” to Earth observation records from cuts to NASA’s earth sciences budget under President George W. Bush. “So it seems we were just trying to correct this problem,” Peters said about the increases since 2009.

Senator Bill Nelson (D–FL), the top Democrat on the full commerce committee and the only current member of Congress to have flown in space, took a more gentlemanly tack. “Let me point out that budgets are not always as clear as what we think they are,” he said, noting that several other NASA accounts also support exploration activities. At the same time, he rejected Cruz’s attack on the discipline. “Earth science relates directly to everything we are doing in space exploration,” Nelson asserted. “And I would draw that distinction for folks who think that it’s not fashionable, that NASA doesn’t need to do earth sciences.”