Read the NASA overview of the results of Viking’s biological experiments on Mars

The Viking landers were the first spacecraft to conduct experiments on Mars

NASA’s Viking 1 and 2 missions tested soils for signs of life, captured images, and studied the Martian atmosphere, revealing evidence of ancient water flow, volcanic soil, and a thin carbon dioxide atmosphere.

Planetary exploration and the search for extraterrestrial life kicked off with Viking

NASA's Viking 1 and 2 missions revealed Mars' geological activity and potential for past life through their evidence of past surface water. Viking 1 held the record for the longest Mars surface operation until the Opportunity rover surpassed it in 2010.

Congress settled for the Viking program after canceling the Voyager Mars program

NASA's proposed Voyager missions to Mars and Venus in the 1970s were canceled due to budget cuts and the Apollo 1 fire. The Viking program's smaller scope—focused on data collection—was the economically viable alternative to manned Mars mission proposals.

Viking established entry, descent, and landing methods for future planetary visits

The most significant engineering challenge was slowing the Viking lander, which would move through space at nearly 29,000 kilometers per hour before reaching Mars. This required the invention of supersonic parachute technology, which is still used today.

Explore the Spirit and Opportunity Martian rovers

The twin machines were tasked with studying the geology of Mars to identify evidence of past water activity, determine the composition of minerals, rocks, and soils, and perform "ground truth" experiments to calibrate and validate observations made by Mars orbiters.

A four-billion-year-old meteorite reignited the debate about life on Mars

Recovered from Antarctica in 1984, ALH84001 contained organic compounds, magnetite and iron sulfide grains of potential biological origin, and features that resembled fossilized bacteria. With technological advancements, scientists found abiotic origins for these features in the following decades.

Questioning the results of life on K2-18b

An analysis of the atmosphere of an exoplanet called K2-18b identified the presence of biosignatures—molecules that are created by living things on Earth. This discovery may indicate life exists beyond Earth, but the lack of environmental data complicates the interpretation of results.

View an interactive collection of historical documents from the Viking project

This collection includes original mission bulletins, engineering and planning documents, and interview segments from more than 80 Viking team members who made the historic exploration of Mars’ surface by a lander possible.

The USSR’s Venera program made the only successful landings on Venus

While the Soviet space program is famous for launching the first satellite and human into orbit, its most extraordinary feat was the Venera missions—probes that captured data, images, and audio from Venus’s brutal surface. No other nation has repeated the achievement.

How NASA measures marsquakes

Most probes sent to other planets and asteroids focus on surface phenomena, but NASA's InSight Lander is interested in looking deeper. Studying marsquakes as well as the red planet's crust and core, InSight provided four years of insight into how the rocky planets of the inner solar system formed.

NASA uses extreme Earth environments to prepare for space exploration

Analog missions in volcanic terrains and craters mimic Martian and lunar environments. Crew members operating in these missions, including at sites in Utah, Nevada, Arizona, and Hawai'i, test suits and specialized space instruments under simulated conditions.

Some 19th century astronomers thought Mars was inhabited

As telescope technology advanced, astronomers became able to observe the surfaces of objects in our solar system with greater detail. The dips, valleys, and lines crisscrossing Mars, particularly, captured onlookers' imagination, leading some to speculate that the seemingly organized features could only have been created by an intelligent civilization.

Before Biosphere 2, the Soviet BIOS-3 system tested semi-closed ecosystems

Built from 1965 to 1972, the habitat hosted 10 experiments with crews ranging from one to three individuals who had their air recycled by algae and grew their own wheat and vegetables. However, dried meats were routinely brought into the facility to balance crew members’ diets.

Viking mission planning director Gentry Lee (1942–) on getting to Mars

"We didn't know then what we know now, which is how tough it really is to land on Mars."

The inhabitability of the Martian environment presents significant colonization risks

Terraforming the thin atmosphere, toxic dust, extreme cold, and lack of magnetic field is infeasible, given limitations to the size of what can be sent to Mars. NASA and SpaceX are instead exploring creating underground shelters.

What did the Vikings eat?

Examining a culture's culinary practices gives insight into its social structure, skills, and ideology. This article follows culinary archaeologist Daniel Serra as he explores the food habits and choices of Vikings. His findings have effectively ended "the myth of Vikings gnawing off the meat of the bones of wild animals," with evidence providing a clearer picture of Viking society as filled with farmers who didn't have time to hunt.

Spontaneous metabolism may give clues to origins of life

Read this article to learn more about the discovery that suggests that metabolism could have begun spontaneously on our planet—and why it means that scientists may need to rethink how we define life’s origins. A team of researchers at the...

Scientists used to speculate about life on the moon

In the 17th century, Galileo's observations suggested the moon could be inhabited, leading to fictional speculations about lunar life. In the 19th century, stories were published claiming the discovery of various creatures, including human bats. The Apollo missions in the 20th century explored the possibility of life there, but further exploration showed this idea to be less likely than before.

Depending on environment, aliens' bodies would have wide-ranging possibilities

Humans tend to imagine aliens as humanlike, but that's probably unlikely. From small space spiders to metallic carnivores, life on other planets—and how we could interact with it—is difficult to imagine.

Microgravity can alter the evolution of viruses and bacteria

Experiments conducted on the International Space Station have shown that microgravity environments can delay viral and bacterial infections and induce mutations not seen on Earth. These mutations could have implications for long-term space missions and human health and suggest space can serve as a testing ground for developing new therapeutic approaches.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

Learn how environmental conditions are optimized to increase bioremediation efficacy

Through biostimulation, Indigenous microbes are provided with moisture, nutrients, or oxygen to prevent their death and ensure optimal progression of their biochemical reactions. Bioaugmentation can introduce new microbial cultures to target specific compounds not natively found in the environment, while landfarming can spread or aerate contaminated soil to improve access to contaminants.

The lifestyles of early humans

For 2.5 million years, humans lived on Earth without leaving a written record of their lives—but they left behind other kinds of remains and artifacts.

What revisiting a 1979 experiment reveals about ecosystem recovery after deep-sea mining

A 2023 study co-led by the National Oceanography Centre and the Natural History Museum, London, found that tracks made by the mining vehicle remained largely unchanged since 1979. Small animals, such as amoeba-like xenophyophore, were seen in the cleared areas, but sightings of larger animals known to live in the region were much rarer. (Some readers may experience a paywall.)

Watch a time-lapse from space of photosynthesis across Earth

Using NASA satellite imagery, carbon absorption can be tracked and serves as a proxy for photosynthetic activity on land and in the oceans. Over the course of a year, seasonal changes can be observed as plants become dormant in the fall and active again in the spring.

Despite privacy risks, scientists are using DNA in the air to assess ecosystem health

While DNA in soil and water samples has long been used for such analyses, airborne DNA is being incorporated into such efforts to monitor individual species abundance, detect invasive species, measure biodiversity, and determine the success of conservation actions. Future work may include detecting attacks from biological weapons.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

Explore the archaeological treasures of Pompeii, the city buried under volcanic ash when Mount Vesuvius erupted in 79 CE.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

SpaceX's S-1 or 'prospectus' revealed many previously unknown details about the company, including its unprofitability despite doing $18.7B in revenue in 2025, exactly how many voting shares Elon Musk will have in the company (roughly 85%), and more.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

A vending machine run with Anthropic's AI went out of business after it was convinced to give away items for free and sell a video game console.

In 2009, the nation was gripped by the story of a missing young boy who was believed to be floating over Colorado in a homemade balloon, until it was revealed that he was at home the whole time.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

'Saturday Night Fever,' the 1977 film that introduced disco to the mainstream, was based on a fabricated magazine story.

Explore an interactive map of battles from the American Revolution, along with detailed summaries of each engagement

The Beatles' US label rejected the band's first two singles, 'Please Please Me' and 'From Me to You,' with one executive calling the band 'dead in the water.'