The Laser Interferometer Space Antenna, a joint project with the European Space Agency, is designed to test technologies that could one day detect gravitational waves. Photo / Nasa
President Donald Trump’s fiscal 2026 budget request, if approved by Congress, would kill many of Nasa’s plans for robotic exploration of the solar system.
Gone, too, would be multiple space-based missions to study Earth, the sun, and the rest of the universe.
Among the planets that would get less attention are Venus, Mars and Jupiter.
But the planet facing the biggest drop in scrutiny from space is our own.
The Trump budget proposal calls for reducing Earth science funding by 53%.
Also spiked: a mission that would take a close look at Apophis, a jumbo asteroid that will pass just 32,000km from Earth – closer than geosynchronous satellites – on April 13, 2029.
The White House Office of Management and Budget said in its request that Nasa’s current spending of more than US$7 billion ($11.6b) a year on nearly 100 science missions is “unsustainable”.
“The budget provides US$3.9b for [Nasa’s science directorate], supporting a leaner, more focused Science [programme] that reflects the Administration’s commitment to fiscal responsibility,” the budget request states.
The Planetary Society, a non-profit advocacy group for space science, estimates that 41 current or planned missions, roughly a third of Nasa’s portfolio, would be terminated if the Trump budget is approved as written.
Trump’s proposals would hammer the Nasa workforce, triggering the loss of thousands of civil service and contractor positions.
Congress has the power of the purse, however, and could save missions targeted for termination.
The Senate Commerce, Space and Transportation Committee, chaired by Senator Ted Cruz, is pushing to protect much of Nasa’s funding but is primarily concerned with saving existing elements of the agency’s Artemis moon programme. On Friday, the committee proposed restoring billions of dollars to a variety of Nasa projects.
Here are some of the imperilled missions:
Venus, second rock from the sun, is virtually the same size as Earth and billions of years ago could have been a congenial world for the emergence of life.
Today it is a hellish place, roasted by a runaway greenhouse effect. The scientific community is eager to understand the forces behind this metamorphosis.
Nasa’s Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy probe, scheduled to launch in 2031, is designed to orbit Venus and produce “incredibly detailed radar maps of Venus’s surface”, the agency said.
The Deep Atmosphere Venus Investigation of Noble gases, Chemistry and Imaging spacecraft, scheduled to launch in 2029, is designed to fly close to the top of the planet’s clouds and drop a probe towards the surface.
According to Nasa, “after the probe travels halfway to the surface, the parachute will be jettisoned; at this point, Venus’s atmosphere becomes so thick, 90 times thicker than Earth’s, that the probe will slow down naturally, settling like a stone in water”.
Scientists expect it to provide close-up images of the planet’s surface.
The Polarised Submillimeter Ice-cloud Radiometer is a modest mission (US$37 million, not including launch costs).
Two small satellites would orbit the globe to “help humanity better understand Earth’s dynamic atmosphere and its impact on climate by studying ice clouds that form at high altitudes throughout tropical and sub-tropical regions”.
The European Space Agency would send a rover to Mars, with an assist from the United States.
According to Nasa, the agency’s astrobiology programme “has contributed resources to aid in the scientific, engineering, and technical development of the ExoMars Rosalind Franklin rover”, named for the British chemist who provided crucial evidence of the structure of DNA.
“Nasa’s participation includes providing critical elements to the rover’s astrobiology instrument, the Mars Organic Molecule Analyser (MOMA).”
The Chandra X-ray Observatory would see its budget go from US$69m to zero.
The Trump budget asks for a two-thirds reduction in the funding for astrophysics.
Nasa is preparing to launch the Nancy Grace Roman Space Telescope in two years, and the Trump budget proposal gives that mission some funding, though less than previously planned. The Habitable Worlds Observatory, envisioned as the next great space telescope, would receive minimal funding.
The Mars Atmosphere and Volatile EvolutioN orbiter has been studying the planet’s upper atmosphere since 2014.
Funding for ongoing data collection and analysis is terminated in the Trump budget proposal.
The spacecraft would circle Mars without producing science.
Lacking monitoring from Earth, the spacecraft could lose functionality and, if its orbit degrades, could eventually crash to the surface, according to Bruce Jakosky, a senior scientist at the University of Colorado and principal investigator emeritus for the mission.
Jakosky said Trump’s proposed budget is not only devastating for Nasa’s science portfolio, it also won’t help the agency’s aspiration to put humans on Mars.
“The cancellation of ongoing Mars missions and Mars Sample Return eliminates major efforts to understand the environmental conditions that astronauts will face, to understand Mars as a planet, and to prepare the science for human missions,” Jakosky said in an email.
Nasa’s Osiris-REx mission took samples of the Earth-crossing asteroid Bennu to study in laboratories back on Earth.
The spacecraft is still flying, and the agency has given it a legacy mission, called Osiris-Apex – for Origins, Spectral Interpretation, Resource Identification and Security-Apophis Explorer.
The goal is to study gravity-induced changes in the asteroid Apophis when it passes very near Earth in four years.
If funding is terminated, as Trump proposes, the spacecraft will circle the sun indefinitely without yielding any science.
The Laser Interferometer Space Antenna is a proposed joint mission with the European Space Agency to study gravitational waves.
Three spacecraft would form an equilateral triangle about a million miles apart. They would act as a single antenna, capable of detecting very long wavelength ripples in space-time caused by the collision of black holes and neutron stars.
According to Nasa, “studying gravitational waves gives enormous potential for discovering the parts of the universe that are invisible by other means, such as black holes, the Big Bang, and other, as yet unknown, objects.”
The US contribution would be terminated.
This ambitious mission, conceived in partnership with Europe, has been on life support because of delays, cost overruns and significant technical challenges.
Former President Joe Biden’s Nasa administrator, Bill Nelson, declared the mission timeline unacceptable, and the agency asked private industry to produce new ideas to bring back samples already obtained by the Perseverance rover. Trump’s budget proposal provides no funding for the project.
The twin spacecraft, launched in 1977 and renowned for producing stunning images of the outer solar system, are now the most distant objects ever sent into space by humans.
Voyager 1 is more than 24 billion km from Earth and Voyager 2 more than 21 billion km away, putting them beyond the heliopause, where the “solar wind” of particles streaming from the sun terminates.
The proposed Trump budget trims Voyager’s funding from US$7.8m to US$5m in 2026 and for the following two years, then drops to zero in 2029.
At some point, a termination of funding was bound to happen, because the Voyagers are running out of steam, metaphorically.
The spacecraft are powered by the radioactive decay of plutonium-238. That power is dwindling, and Nasa has been forced to turn off some of the scientific instruments.
Still, they continue to study the particles and radiation in interstellar space, science that is not readily duplicated. Telescopes and computer modelling can’t do what the Voyagers have done by actually going there.
These projected cuts to Nasa’s space science missions are not final. Lawmakers may champion missions that affect their home states and districts.
The Senate Commerce Committee hopes to protect Nasa’s budget, which the White House had proposed to cut by nearly one-fourth. Most of the Senate-backed funding would go towards human spaceflight, not science.
The committee would, for example, extend the lifetime of Nasa’s heavy-lift Space Launch System rocket, which the White House had proposed cancelling after the Artemis 3 lunar landing, scheduled for 2027.
The Senate proposal would also preserve money for Gateway, a space station that would fly in lunar orbit.
People familiar with the effort to add the money to Nasa’s budget said they do not anticipate pushback from the White House – in part because of Trump’s sudden falling out with Elon Musk. The cancellation of the SLS rocket could have significantly benefitted Musk’s SpaceX, which is developing the heavy-lift Starship rocket.
Any Nasa dollars that flow to commercially oriented companies would benefit not just Musk’s space venture but also Jeff Bezos’ Blue Origin. (Bezos owns the Washington Post).
The Trump budget proposal calls for $1b in new funding for Mars-related human exploration.
That includes funding to “test capabilities for a near-term human-class Mars lander”. Money would also go to developing spacesuits tailored for life on Mars.
This falls short of the kind of drastic strategic pivot, from the moon to Mars, that seemed possible when Musk began regularly campaigning with Trump and both expressed a desire for a Mars mission within a few years.
Any Mars mission would face tremendous technical and budgetary challenges.
Nasa has never landed a payload on Mars that weighs more than a small car.
Mars has only about 1% the atmospheric density of Earth, notoriously too thin to help slow down an incoming vehicle, but just thick enough to cause trouble.
