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

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.

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.

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.

View the first photos ever taken from the Martian surface, courtesy of NASA's Viking Project.

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

Three experiments on the Viking 1 and 2 landers searched for signs of metabolic activity in soil samples, indicating the presence of microorganisms. No definitive evidence of life was found in any experiment or lander imaging.

Voyager spacecraft defied expectations and only powered down after 47 years in space

Originally built for a four-year mission, Voyagers 1 and 2 used a rare planetary alignment and gravity assists to reach interstellar space. With limited power and aging systems, they will continue to send data until the mid-2030s. (Some readers may experience a paywall.)

Intended to last four years, the Voyager spacecraft have lasted nearly five decades

Launched in 1977, the Voyager probes still send data from billions of miles away, guided by engineers who’ve turned down promotions to stay with the mission. The team continues to support the probes as they move 37,000 mph through space.

NASA's big dream that never came to life

Conceived in the early 1960s, the Sea Dragon was an audacious ocean-launched rocket design that would have dwarfed the Saturn V in both scale and payload—but its extreme engineering challenges kept it firmly on the drawing board.

Explore a timeline of every mission to Mars through 2020

The US has conducted the most missions (23) and has the highest success rate (74%), followed by Russia (18 missions at 5%). The first successful orbiter was Mariner 4, while Viking 1 was the first successful lander.

NASA's ESCAPADE mission will study Mars' atmosphere

The $80M mission—a collaboration between private companies, universities, and NASA—sent two copy machine-sized orbiters on a Blue Origin rocket to the red planet to study its magnetic field and atmospheric loss.

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.

Voyager 1 and 2 are the only spacecraft to reach and study interstellar space

The Voyager Interstellar Mission extended beyond the original planetary flybys to explore the solar system's edge and beyond. Voyager 1 and 2 crossed the heliosheath—the boundary between the solar wind and the interstellar medium—in 2012 and 2018, respectively.

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."

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

Explore a NASA timeline of the entire Voyager mission

This infographic leads users through the entire Voyager mission timeline, starting at its conception and moving through launch, to each destination, and finally, the Voyagers' crossing into interstellar space.

A return to Uranus

There's been only one mission to Uranus before—Voyager 2 passed by the ice giant in 1986 before heading off into interstellar space. NASA's recent planned itinerary for space missions lists Uranus as the highest priority over the next decade. The seventh planet is 20 times as far from the sun as Earth, and researchers say its study will shed light on how the outer half of the Solar System formed.

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.

The Mars Climate Orbiter—a $125M spacecraft designed to study Martian weather and climate—was lost because ground software used imperial units while onboard software used metric units.

NASA fixed Voyager 1’s glitchy memory from 24 billion kilometers away

In November 2023, Voyager 1 began sending unusable data due to a stuck bit in a decades-old memory chip. After months of investigation, engineers managed to reroute the faulty code to a new memory location, restoring functionality in April 2024.

The Challenger disaster ended NASA's plan to fly ordinary Americans in space

The explosion of the Challenger halted NASA's civilian spaceflight ambitions for decades, including plans to send teachers, journalists, artists, and other nonastronauts into orbit—an effort aimed at building public support that quietly disappeared after the 1986 disaster.

Voyager science teams still collect valuable space data using four active tools

These instruments track magnetic fields, solar wind particles, radio emissions from the heliopause, and hydrogen levels in the outer heliosphere. Even though each Voyager sends data at just 160 bits per second, NASA receives 6–8 hours of tracking data daily.

Only 34% of Americans supported the Apollo program in 1967

After a fire killed three astronauts on the launchpad of Apollo 1, the public became ambivalent about funding the multibillion-dollar program until the successful moon landing in 1969. The landers alone cost $388M, while each spacesuit cost $100,000.

Space tourism opportunities have been explored since the end of the Apollo era

In the 1970s, Rockwell International, a NASA contractor, and others investigated manufacturing passenger modules that could fit into the Space Shuttle's payload bay. NASA also opened spaceflights to nongovernment professionals, but many such programs were ended after the Challenger disaster, which killed the first Teacher in Space participant.

Explore a timeline of NASA's exploration of Mars

NASA has studied Mars extensively over 60 years using telescopes, orbiters, and rovers. From April 2021 to January 24, the Ingenuity helicopter completed its technology demonstration objective by flying more than 17 kilometers above the Martian surface.

NASA's budget makes up less than 0.4% of total US spending

NASA's annual budget consists mainly of human spaceflight activities (50%) and robotics and scientific research programs (30%). It peaked at almost $70B in 1964 but has been below $30B since 1995, coming from discretionary nondefense funds.

Why haven’t humans reached Mars?

Mars remains the most viable interplanetary destination due to its relatively habitable orbit. There are many challenges, however, including the huge distance to Mars, the need for advanced propulsion systems, uncertainty over the impacts of long-duration space travel on astronauts, and the need for safe landing techniques and equipment to handle Martian conditions. Human-manned missions to Mars are not likely to occur until the 2030s at the earliest.

The Polaris Dawn program led to the first commercial spacewalk

As part of the Polaris program, this first mission included a crew comprising astronauts and SpaceX engineers, who conducted scientific experiments and cultural outreach, such as raising funds for St. Jude Children's Research Hospital.

The Polaris Dawn was a privately crewed spaceflight

SpaceX's Crew Dragon capsule Resilience spent five days in low Earth orbit as part of the first of three planned missions under the name Polaris Dawn. The historic journey took participants farther away from our planet than anyone has been since the Apollo missions.

Supersonic parachutes have allowed rovers to safely land on Mars' surface

The disk-band-gap parachute design was first developed for the Viking Project in the 1970s. Since then, it has been reinforced and uses stronger materials to handle larger payloads—including the 2020 Perseverance rover—landing it a world record.

Voyager carries Earth's hopeful greeting into deep space as a message of peace

Along with scientific instruments, each Voyager carried a golden record containing multilingual greetings—ranging from Sumerian and Akkadian to Thai and Cantonese—music, and sounds of Earth intended for any intelligent life that might find it.

NASA was founded in response to early Soviet space achievements

Although starting behind in the Space Race in 1958, NASA became a global leader in humanity's exploration of space with the Apollo program, which placed astronauts on the moon. Since then, it has been responsible for the construction of multiple telescopes, the International Space Station, and development of the Artemis program to return humans to the Moon before eventually reaching Mars.

Big Bird was almost included on the Challenger mission

As part of NASA's early outreach ideas tied to the Teacher in Space program, Sesame Street's Big Bird was briefly considered for a Challenger flight, but the plan was dropped because the oversized costume could not fit safely inside the shuttle.

See the unbuilt rocket design that would have dwarfed the Saturn V

Designed in the early 1960s, the Sea Dragon was a radical concept for an ocean-launched rocket that would have far exceeded the Saturn V in size and payload. The conceptual design was ultimately too risky and impractical to build.

View a media gallery from the assembly of Voyager 1 and 2

This archive includes the many steps it took to put together each Voyager probe. Photos focus on individual parts, like the 8-track tape deck, the large dish-shaped antenna, and its long arm magnetometer boom.

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.

Voyager mission's Golden Record captures Earth’s essence for alien discovery

Housed aboard Voyager 1 and 2, each record serves as a time capsule of human culture and a peaceful introduction to any intelligent life. Even if never played, the records can outlast humanity and travel through space for a billion years.

James Webb championed both space science and human spaceflight at NASA

As NASA Administrator during the 1960s, Webb prioritized a balanced approach between manned missions and scientific research, fostering advancements in astronomy, robotic exploration, and university involvement. Despite having no background in science or engineering, Webb oversaw more than 75 space science mission.

The team responsible for the first interplanetary sundials included Bill Nye

While reviewing designs for instruments to be carried by future Mars rovers, Nye suggested adapting the function of a calibration tool, which would be used by the Spirit and Opportunity rovers to help calibrate the brightness and color of their panoramic cameras on the Martian surface.

Explore what Challenger was supposed to do on its mission

STS-51L's planned seven-day mission included deploying satellites, studying Comet Halley, conducting fluid dynamics experiments, and broadcasting live lessons from orbit—routine scientific and educational tasks that were never carried out after the shuttle was lost shortly after launch.

In honor of scientific exploration, all five launched space shuttles were named after ships that traveled the oceans, but a campaign from 'Star Trek' fans led to the shuttle prototype being named Enterprise.

Voyager Station, the world's first space hotel, is planned for 2027

The structure spans 488 meters in diameter and will rotate to simulate one-sixth of Earth's gravity while circumnavigating the planet every 90 minutes. The Voyager Station is designed to accommodate 450 guests and 150 crew members, providing amenities such as restaurants, a sports hall, and a movie theater.

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.

Elon Musk's $100M investment in SpaceX was lost to three failed rocket launches

The attempts with Falcon 1 endangered the company's future but provided valuable information from which to iterate and follow up with the successful first privately funded orbital launch in history and multiple ISS resupply missions.

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.

Explore the interior and exterior of the Atlantis and Endeavour space shuttles, including their flight decks, cargo bays, and other compartments.

NASA plans to build a lunar-orbiting space station to support future missions to Mars

Planned for a 2027 launch, NASA Gateway is a lunar-orbiting space station meant to support Artemis lunar missions and future Mars travel. This resource includes an interactive 3D model of the proposed station's modules and layout.

Although it drew inspiration from spaceplane concepts of the 1920s, the Space Shuttle program began to take shape after the Space Race, as the US sought to establish a space station and a reusable transportation system for astronauts and satellites.

NASA and SpaceX combine public support and funding with private enterprise

Rather than competitors, SpaceX and NASA are mutually beneficial collaborators. Without NASA contracts, SpaceX may have run out of funding, and without the low-cost tech of SpaceX, NASA may have been left without a US-based launch system.

Voyager 1 captured Earth as a 'Pale Blue Dot' from 6 billion kilometers away

On Feb. 14, 1990, NASA's Voyager 1 space probe took the farthest photo of Earth ever captured. Earth appears so small in the image that it takes up less than a single pixel out of 640,000 in the photo's frame.

The Teacher in Space program was launched in 1984 to highlight spaceflight in US classrooms

Announced by President Ronald Reagan, the program drew more than 11,000 teacher applicants nationwide. Christa McAuliffe was selected to fly on STS-51L, with plans to teach live lessons from orbit before the Challenger disaster ended the mission.