NASA is hunting for aliens in Yellowstone’s boiling hot springs

The Search Starts Underground

Yellowstone National Park draws millions of visitors each year to watch geysers erupt and hot springs steam. But beneath those colorful pools lives something most people never see.

Microscopic organisms thrive in water hot enough to cause third-degree burns, and NASA believes these tiny creatures could teach us how to find life on Mars.

The connection between a Wyoming hot spring and the Red Planet starts with a question scientists have asked for decades, and the answer may finally be within reach.

Grand Prismatic Hides Invisible Life

The Grand Prismatic Spring is the largest hot spring in the United States and the third largest in the world.

It measures about 370 feet across and more than 121 feet deep, with water temperatures reaching up to 190 degrees Fahrenheit. From above, the spring looks like a giant eye ringed in orange and red.

But the real story happens where you cannot see it.

Below the bubbling surface exists a diverse system of microbes, which scientists have been studying for decades. These organisms have already changed medicine.

Now they might change our understanding of life itself.

Rainbow Colors Are Living Things

The Grand Prismatic Spring gets its name from colors that match light through a prism.

The center reaches nearly 189 degrees Fahrenheit, too hot to sustain most life, so it appears deep blue from sunlight scattering in the clear water.

Each ring of color moving outward represents a cooler temperature zone where different bacteria can survive.

A type of cyanobacteria called Synechococcus lives in the yellow band, where temperatures hover around 165 degrees. The mats produce colors from green to red depending on the ratio of chlorophyll to carotenoids.

What looks like paint is actually life.

Three Types of Extremophiles Thrive

Three main extremophiles can be found in Yellowstone: thermophiles, which thrive at temperatures above 113 degrees Fahrenheit; acidophiles, which thrive in extreme acidity; and chemolithotrophs, which obtain energy from inorganic chemicals like sulfur or iron rather than organic matter.

Scientists call them extremophiles because they love conditions that would kill almost anything else.

Yellowstone has more geysers than the rest of the world combined, which means it has more of these extreme environments packed into one place than anywhere on Earth. Each hot spring is its own laboratory.

Why Chemolithotrophs Matter Most

Chemolithotrophs are particularly important for NASA because they obtain energy from inorganic chemicals rather than from the sun. Today, all life that the naked eye can see is supported by the sun.

Plants rely on photosynthesis, herbivores eat plants, and carnivores eat herbivores. But chemolithotrophs break that rule.

They survive on sulfur, iron, and hydrogen gas instead of sunlight. Early Earth had little oxygen and no plants, so the first life may have survived the same way.

Mars has no sunlight reaching underground, but it has plenty of chemicals. If life exists there, it probably looks a lot like what lives in Yellowstone's boiling pools.

Tom Brock's 1966 Discovery

In 1966, Dr. Thomas Brock and his colleagues isolated a new bacterium from a hot spring in the Lower Geyser Basin.

They collected a sample of a photosynthetic mat thriving at 160 degrees Fahrenheit in Mushroom Spring. Brock and his undergraduate student Hudson Freeze named the organism Thermus aquaticus.

Before this discovery, scientists believed nothing could live above about 140 degrees. Brock proved them wrong, and that single finding opened an entire field of research.

Microbiologists worldwide started looking for other microbes in extreme conditions. They found life in places nobody thought possible.

One Enzyme Won a Nobel

After obtaining a laboratory sample of Thermus aquaticus in the 1980s, Dr. Kary Mullis identified an enzyme in the bacterium that he named Taq polymerase.

This enzyme can copy DNA at high temperatures that would destroy most other enzymes.

With the use of Taq polymerase, Mullis developed the Polymerase Chain Reaction technique, which allows scientists to replicate millions of copies of a DNA sequence.

Mullis, jointly with Michael Smith, was awarded a Nobel Prize in chemistry in 1993. A bacterium from a Wyoming hot spring made modern genetics possible.

Your COVID Test Started Here

If you had a rapid PCR test during the COVID pandemic, the basis of that test has its roots in the hot springs of Yellowstone.

The same technology identifies criminals through DNA evidence, diagnoses genetic diseases, and sequences entire genomes. The global PCR market was valued at $9.91 billion in 2024 and is projected to reach $19. 23 billion by 2032.

All of it traces back to one sample from one hot spring, collected by a professor and his student nearly 60 years ago. Brock was doing basic research with no idea where it would lead.

Extremophiles Leave Signatures Behind

Extremophiles often leave behind evidence of their shapes as biological signatures, which can be found and studied at Yellowstone. When these organisms die, they leave chemical and mineral patterns in the rock.

The chemical precipitates found in hot spring waters can entomb and preserve cells, making hot springs a good place to look for biosignatures left behind by past life.

NASA scientists are now looking for similar signatures in rocks on other planets in the hope of finding evidence of past microbial life beyond Earth.

The minerals around Yellowstone's springs are teaching scientists exactly what to look for.

Mars Shows Ancient Hot Springs

In May 2007, the Spirit rover disturbed a patch of ground with its inoperative wheel, uncovering an area 90 percent rich in silica.

The feature looks like the effect of hot spring water or steam coming into contact with volcanic rocks.

There is a plethora of evidence for volcanic hydrothermal environments in Mars' past, and the potential presence of hot springs has played an important role in selecting landing sites for missions.

If Mars once had hot springs like Yellowstone's, it may have had the same kinds of extremophiles. The rock formations look strikingly similar.

Perseverance Found Something in 2025

In September 2025, NASA announced that a sample collected by the Perseverance rover from a rock named Cheyava Falls contains potential biosignatures.

The spots on the rock could have been left behind by microbial life if it had used the raw ingredients in the rock as an energy source.

Scientists think the spots may indicate that billions of years ago, chemical reactions in this rock could have supported microbial life.

Acting NASA Administrator Sean Duffy called it the closest we have ever come to discovering life on Mars. The samples are waiting to be returned to Earth.

Yellowstone May Prove We're Not Alone

Eric Boyd, Professor of Microbiology at Montana State University, said NASA funds his research at Yellowstone to better understand life's origins.

If we understand the conditions that support microbiology on Earth, that will help narrow our search for life on other planets. The connection between a boiling pool in Wyoming and a cold desert on Mars seems unlikely.

But the organisms in Yellowstone have already revolutionized medicine. Now they may answer the biggest question humans have ever asked.

The hunt for alien life started in a place you can visit this summer.