The total solar eclipse of March 8-9, 2016, as seen by the NASA-NOAA Deep Space Climate Observatory (DSCOVR) spacecraft.

Five NASA Earth-science missions are now on the chopping block.

Four we already knew about; they were zeroed out in the White House's preliminary, or "skinny," 2018 budget request, which was unveiled in March. The fifth, called the Radiation Budget Instrument (RBI), was revealed yesterday (May 23) with the release of the Trump administration's fleshed-out 2018 request.

RBI had been part of Joint Polar Satellite System 2, a NASA and National Oceanic and Atmospheric Administration mission scheduled to launch to Earth orbit in late 2021. The instrument would have measured the effect of clouds on Earth's energy budget, said Andrew Hunter, NASA's acting chief financial officer. [Watch: NASA's Future Plans in 2018 Budget Request]

But it wasn't to be.

"We were experiencing schedule and technical difficulties on RBI," he told reporters during a budget-explaining teleconference yesterday. "It’s always tough to terminate a mission, but it becomes a matter of priorities, and it was a budget-related decision."

The other four Earth-science projects to get the ax in the proposed 2018 budget are the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite; the Orbiting Carbon Observatory-3 (OCO-3) experiment; the Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder; and the Earth-viewing instruments aboard the Deep Space Climate Observatory (DSCOVR) spacecraft.

The first three missions in that list were still in development, but DSCOVR launched in February 2015 and has since returned many spectacular images of Earth from its vantage point 930,000 miles (1.5 million kilometers) from our planet.

If the budget proposal becomes law as-is — which is far from guaranteed, since it must be passed by Congress — those photos will stop coming in. But DSCOVR will continue with its other work: helping provide warning of solar storms by studying the stream of charged particles that flow from the sun.

Cutting the five Earth-science missions would save NASA $191 million in 2018, and about $850 million through 2022, Hunter said.

The budget request gives the space agency's Earth-science division $1.75 billion in 2018, compared with $1.92 billion this year. (NASA planetary science, on the other hand, would get a bump, from $1.85 billion in 2017 to $1.93 billion next year.)

The skinny and fleshed-out 2018 budget requests are very similar, the changed fate of RBI notwithstanding. For example, both allocate $19.1 billion to NASA next year, down from $19.7 billion in 2017.

Both requests also provide continued support for the 2020 Mars rover and the Europa Clipper, a flyby mission to Jupiter's ocean-harboring moon Europa. And both cancel the Asteroid Redirect Mission, a project that would have plucked a boulder off a near-Earth asteroid and hauled it into orbit around the moon.

You can read NASA's 2018 budget-request documents here.

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