Why haven’t humans reached Mars?

Besides Earth, Mars is the only possibly habitable planet in our solar system

Sending humans to Mars in the following decades poses significant challenges, from the vast distance covered to get materials there to powering technology during weekslong dust storms. Research is ongoing to develop life support systems that can regenerate or recycle consumables.

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 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.

Experts ponder nuclear rockets to send humans to Mars

Nuclear rocket technology might be the fastest, safest way to get to the red planet. But if NASA wants to go, it should start development now.

Imagining the best places to live on Mars

Because conditions on Mars are pretty extreme for humanity, we tend not to think about living there, since everywhere on Mars feels a bit threatening. This imaginative essay uses current geographical knowledge of Mars to visualize what it would look like if humanity could alter its climate to make it widely habitable, a process known to sci-fi readers as terraforming. Given that transformation, where would the hottest neighborhoods be located?

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.

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.

Why are we finally returning to the moon after 50 years?

After 50 years, NASA is heading back to the moon. Artemis missions will push beyond Apollo, landing astronauts on the moon’s south pole by 2027. But why the long wait? Budget cuts, shifting priorities, and outdated tech stalled lunar exploration—until now. With new goals and modern tech, NASA is ready to return.

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.

Five hazards of human spaceflight

From space radiation to isolation, humans struggle when it comes to traveling and living in space. What does this mean for long-term spaceflight? This hour-long podcast episode attempts to answer that question while detailing five major spaceflight hazards.

View the surface of Mars from NASA's Perseverance

Simulate a visit to the red planet with the Mars 2020 Perseverance Rover. This 3D interactive experience lets you explore various locations on the martian surface. See closeup images the rover has taken and view key points of interest. It's the next best thing to being there and certainly far safer!

The 45 planets astronomers think are most likely to host alien life

The list includes familiar names like Proxima Centauri b (4 light-years away) and four planets in the TRAPPIST-1 system (about 40 light-years away), but even the nearest of those would take humanity roughly 114,000 years to reach at current spacecraft speeds. The list's real near-term value is as a targeting guide for the James Webb and upcoming Nancy Grace Roman space telescopes.

SpaceX was built to achieve Elon Musk's vision of making humans an interplanetary species

Learning quickly from early Falcon rocket failures and clashes with vendors and safety regulators, the company has focused on reusability as a first step to reaching Mars and is backed by NASA funding to do so.

Has anyone had sex in space?

Reproduction is a basic human function, and while we've spent decades in space, no research has been done into the process. With many discussing the possibility of human-occupied bases on the moon, Mars, and more, understanding how sex works outside...

Gravity assists are crucial for space travel beyond Mars

By traveling near a moving celestial object, a passing object can gain or lose speed and change direction due to the acceleration provided by their mutual gravity. Some missions are planned around spacecraft performing multiple assists, or slingshots, to reduce fuel requirements for long-distance travel.

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.

Mar's moons, Phobos and Deimos, are thought to be captured asteroids

Of the two Martian moons, Phobos orbits more quickly, completing three revolutions a day. It gets 1.8 meters closer to Mars every year, and may crash into the planet in about 50 million years.

In 2018, SpaceX launched a Tesla Roadster into heliocentric orbit for publicity

As of February 2023, the vehicle and its mannequin driver—dubbed "Starman"—have completed three and a quarter revolutions around the sun. One paper estimated that the car has a 22% chance of crashing into Earth within the next 15 million years.

When retired, the International Space Station will undergo a controlled de-orbit

With plans to transition low-Earth orbit operations to private entities, the ISS is expected to be retired by 2030, using a SpaceX de-orbit vehicle. Although reentry will burn up most hardware, NASA intends for any surviving debris to fall into an uninhabited ocean area.

Planets' high orbital speeds prevent them from falling into their host star

Although the gravitational force attracts a planet and the star it orbits around, the large speed the planet orbits with, which is acquired during its formation process, causes it to continuously miss the star as it orbits around it. This is analogous to theoretically throwing a baseball horizontally faster and faster until it's fast enough to orbit the Earth while attempting to fall to its surface.

While geography pertains to Earth's surface features, areography pertains to Mars

Unlike Earth, Mars lacks geological activity and oceans, though geological evidence suggests they both existed in the past. Its northern regions have far fewer craters than the southern ones, indicating that the rock in the north formed more recently.

Orbital spaceflight requires reaching 23 times the speed of sound

After the spacecraft accelerates up to at least 17,500 miles per hour, space tourists can travel in elliptical orbits hundreds of miles above Earth for days or weeks at a time. Suborbital flights instead max out at about 2,200 miles per hour and travel only 50 to 70 miles above Earth's surface for a few minutes.

As of 2025, humans have only dug 0.2% the way to Earth's center

The Kola Superdeep Borehole revealed two billion-year-old fossils and underground water, but the immense temperature and pressure prevented further tunneling. Beyond those depths, scientists know of Earth's interior by analyzing how seismic waves move.

One theory for why we haven't discovered aliens is that they haven't been born yet

There's a chance that human civilization arrived before any other life and aliens will soon emerge. If this is the case, there's also a chance for a competition to rule the Universe.

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

Why don't humans hibernate?

Hibernation is a superpower in the animal world that allows certain species to time travel from difficult times to abundance. This essay in Aeon explains this helpful natural process and why humanity's technological advancements may have hindered our ability to participate in the practice. Learn about the rising interest in human hibernation as a result of modern adversity, and if it could potentially become a reality.

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

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.

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.'

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

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

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.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

US housing costs have risen by roughly 175% between 1991 and 2026—but a growing number of Gen Zers are becoming homeowners anyway. In 2025, 4% of homebuyers were Gen Z, up from 3% the year before.

Venture capital is a form of funding provided to early-stage companies with high growth potential, typically in exchange for an equity (or ownership) stake

This site reaches millions of visitors who are tired of AI chatbots and seeking human connection. Pretend to be an AI chatbot and ask questions, provide answers, and draw for people in real time.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions

Animal phobias are likely the most common type of phobias, followed by an extreme fear of heights.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

Despite being favored by 87% of Americans, Congress does not have term limits.

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

Existentialist writer Jean-Paul Sartre coined the famous phrase 'Hell is—other people' in his play 'No Exit'

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in terms of casualties, forces mobilized, and displacement of civilians.