The discovery of water on Mars has been treated, for almost two decades, as a story about whether life ever existed beyond Earth. But for the engineers who actually plan deep-space missions, the bigger payoff is not microbiology — it is propulsion. NHPR’s Cosmically Curious, the long-running astronomy segment hosted by University of New Hampshire astronomy professor John Gianforte, devoted its newest episode to exactly that distinction: the day Martian ice becomes Martian rocket fuel will be the day humans can realistically plan a return trip from another planet.

The episode is short — Cosmically Curious always is — but its argument lands hard. Water is a logistics problem first and a biology question second. Solving the logistics problem unlocks the biology question, not the other way around.

What the Phoenix Lander Found

Gianforte built the segment around a 17-year-old discovery that has aged better than almost any other piece of NASA hardware-driven science. In 2008, NASA’s Mars Phoenix lander touched down at the Martian equivalent of Earth’s Arctic Circle — a high-latitude site chosen specifically because models suggested the polar regolith might contain frozen water. What Phoenix found, almost immediately, exceeded expectations.

“After it touched down, it discovered that it landed basically on an ice skating rink just a few centimeters below the Martian soil,” Gianforte said in the Cosmically Curious episode. “There was 100% pure water.”

That is a stunning sentence to hear from a planetary scientist. Pure water — not contaminated brine, not heavily salted permafrost, but accessible H₂O in essentially the form a chemist would draw on a whiteboard. The implications fanned out from there.

Drinking Water Is Just the First Use

The headline use of subterranean Martian water is biological. Astronauts on a long-duration Mars mission would need water to drink, water to hydrate freeze-dried food, water for hygiene, and water to grow some portion of their own food in closed-loop greenhouses. Hauling all of that mass from Earth is expensive enough that it dominates the design of every proposed crewed Mars mission. Sourcing water from the Martian subsurface, instead, collapses the launch-mass equation in a way that almost no other resource discovery could.

But Gianforte’s interest is not in the drinking. It is in what comes after. “Of course, water is important because we need it to live,” he said. “If there was ever a Martian colony, it would be smart to place it in a location where we know there is some subterranean Martian ice.”

The Rocket Fuel Argument

Here is where the science becomes engineering. Water, chemically, is two atoms of hydrogen bonded to one atom of oxygen. Both are useful. Both are lightweight. And both, when handled correctly, are the building blocks of rocket propellant.

“Hydrogen and oxygen make it possible to make rocket fuel, so it could go a long way toward reducing the weight and complexity of a spacecraft going to Mars,” Gianforte said. “You can then fabricate your own rocket fuel.”

The principle is straightforward. Send equipment to Mars in advance of the human crew. Have that equipment harvest subsurface ice, melt it, and electrolyze it — split the water into hydrogen and oxygen using power from solar arrays or a small nuclear reactor. Store the resulting hydrogen and oxygen as cryogenic propellant. By the time astronauts arrive, the return-trip rocket fuel is already waiting in tanks. The same principle that makes the Mars trip possible also makes the trip cheap enough to imagine repeating.

This is the architecture NASA has been quietly converging on. The Artemis program’s lunar return is structured around the same logic. Future Mars architecture studies — including the work coming out of the Marshall and Johnson space centers — assume some version of in-situ resource utilization, the technical term for “make your fuel where you land.” Gianforte’s segment is, in a real sense, the public-radio explanation of why those architecture documents look the way they do.

Why Everyone Is Headed to the Lunar South Pole

The same logic that makes Mars water transformational makes lunar water nearly as valuable. The moon’s south pole is now the focus of NASA’s Artemis crewed landings, China’s lunar program, and several commercial lander missions, and the reason is consistent across every one of those plans.

“That’s why everybody’s trying to get back to the south pole of the moon, because there’s water ice to be found there,” Gianforte said. “It’s not only helpful for possible microbial life, but also for future missions to Mars that are going to stay there for a while.”

A lunar south pole base that can produce its own water — and, by extension, its own rocket fuel — becomes a natural staging point for any Mars mission. Launching crewed Mars vehicles from a lunar refueling station, instead of from Earth’s surface or low Earth orbit, dramatically reduces the propellant mass that has to be lifted out of Earth’s gravity well. The moon, in this architecture, becomes a permanent gas station rather than a once-per-program destination.

The University of New Hampshire Angle

Gianforte is not a bystander to this conversation. He directs the UNH Observatory in Durham and has been a consistent public voice for New Hampshire’s involvement in space-science research and education. UNH itself has a long and underappreciated record in space physics — the university’s Space Science Center has built or contributed instruments on multiple NASA missions and operates ongoing research programs in solar wind dynamics, magnetospheric physics, and instrument development.

For Granite State students considering STEM pathways, that local presence matters. New Hampshire has continued to face strain in its overall education system, but its public university system has carved out durable strengths in specific research areas. Space science is one of them, and Cosmically Curious is one of the more visible ways UNH brings that work to a public audience.

Listeners with their own astronomy questions can email cosmic@nhpr.org. Episodes are short, conversational, and air on NHPR with the full archive at the Cosmically Curious page.

Source: Cosmically Curious: Make your own rocket fuel — NHPR

For related coverage, see our reporting on What Came Before the Big Bang?.

How did NASA discover water on Mars? NASA's Phoenix lander, which touched down on Mars in 2008 at a site equivalent to Earth's Arctic Circle, dug into the Martian regolith and discovered nearly pure water ice within a few centimeters of the surface. UNH astronomy professor John Gianforte described the find on NHPR's Cosmically Curious as effectively "an ice skating rink" beneath the soil. Subsequent missions, including the Mars Reconnaissance Orbiter and Mars Express, have mapped much larger subsurface ice deposits across both polar and mid-latitude regions of the planet.
How can water on Mars be used as rocket fuel? Water (H₂O) is composed of two abundant chemical elements — hydrogen and oxygen — that together make a high-performance rocket propellant. By sending automated equipment to Mars in advance of a crewed mission, future explorers could harvest subsurface ice, melt it, and electrolyze it to separate the hydrogen and oxygen, which can then be stored as cryogenic propellant for the return trip. The technique, known as in-situ resource utilization, dramatically reduces the launch mass that has to be carried from Earth.
Why is the lunar south pole important for space exploration? The moon's south pole contains water ice in permanently shadowed craters — a discovery that has reshaped global lunar exploration plans. NASA's Artemis program, China's lunar plans, and several commercial lander companies are all targeting the south pole because lunar ice can be processed into drinking water, breathable oxygen, and rocket fuel. UNH's John Gianforte has emphasized that a lunar refueling station could serve as a staging point for crewed Mars missions, reducing the propellant mass that must be lifted out of Earth's deeper gravity well.