Not yet, but we've sent
The first to contact the surface were two Soviet probes: Mars 2 lander on November 27 and Mars 3 lander on December 2, 1971—Mars 2 failed during descent and Mars 3 about twenty seconds after the first Martian soft landing.
So why haven't humans yet traveled to Mars? According to NASA, there are a number of obstacles that we still need to overcome before sending a human mission to the planet, including technological innovation and a better understanding of the human body, mind and how we might adapt to life on another planet.
The answer seems to be “it's possible”. Many scientists consider Mars and Earth twins because of the similarities between the planets. But they aren't entirely alike. Some challenges would need to be overcome before humans could start calling Mars home.
Is there life on Mars? No, we have never discovered life on the Red Planet, but we have found lots of evidence that suggests Mars could have once supported life in its ancient past. There's even a chance that Mars could be habitable beneath its surface. NASA astrobiologist Heather Graham explains more.
Flexi Says: Right now and for the foreseeable future, humans can only live on Earth. Humans have not traveled very far into space. The Moon is the only other place humans have visited. No other planet in our solar system currently has the conditions to support life as we know it on Earth.
SpaceX CEO Elon Musk said he may join the first colonists on Mars. Before that happens, though, his Starship needs to complete its maiden orbital flight. Before SpaceX's Starship has even completed its first orbital flight successfully, Elon Musk is already dreaming of joining its maiden voyage to Mars.
NASA's New Horizons spacecraft was the first spacecraft to explore Pluto up close, flying by the dwarf planet and its moons on July 14, 2015.
The exploration of Saturn has been solely performed by crewless probes. Three missions were flybys, which formed an extended foundation of knowledge about the system. The Cassini–Huygens spacecraft, launched in 1997, was in orbit from 2004 to 2017.
No people have ever traveled to Jupiter. It's too far away. At this stage we're not even thinking about trying to send astronauts that far away from Earth—we need to get people to Mars or perhaps an asteroid first. Even if we do eventually get people to Jupiter, there will be many challenges.
Visiting Venus
Venus lies just outside the sun's habitable zone. That zone has temperatures that could keep liquid water stable on a planet's surface. No spacecraft have landed on the surface of Venus since 1985. A few orbiters have visited Earth's neighbor in the past decade.
Only our two nearest neighbours Venus and Mars have been landed on. Landing on another planet is technically challenging and many attempted landings have failed. Mars is the most explored of the planets. Mercury could be landed on but the speeds involved and the proximity to the Sun are challenging.
Overall, Mars is cold—its average global temperature is around -80 degrees Fahrenheit—and has a much thinner atmosphere than Earth. Because it has about a sixth of the pressure of Earth's atmosphere, the planet doesn't retain heat very long, causing temperatures to drop quickly.
Mars is a planet with a very similar daily cycle to the Earth. Its sidereal day is 24 hours, 37 minutes and 22 seconds, and its solar day 24 hours, 39 minutes and 35 seconds. A Martian day (referred to as “sol”) is therefore approximately 40 minutes longer than a day on Earth.
The red planet once had a global ocean, rivers, and lakes. Then, the solar wind — charged particles from the Sun — stripped away the Martian atmosphere. As the planet's protective shield faded, all liquid water on the surface evaporated into space, merged with minerals, or fled underground to become water ice.
Jan. 24, 1986: NASA's Voyager 2 made the first - and so far the only - visit to Uranus. The spacecraft came within 50,600 miles (81,500 kilometers) of the planet's cloud tops. Voyager discovered 10 new moons, two new rings and a magnetic field stronger than that of Saturn.
In short, no. As an ice giant, Uranus doesn't have a true surface. The planet is mostly swirling fluids. While a spacecraft would have nowhere to land on Uranus, it wouldn't be able to fly through its atmosphere unscathed either.
Neptune has been directly explored by one space probe, Voyager 2, in 1989. As of December 2022, there are no confirmed future missions to visit the Neptunian system, although a tentative Chinese mission has been planned for launch in 2024.
Answer. The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet. Essentially Pluto meets all the criteria except one—it “has not cleared its neighboring region of other objects.”
Launched 16 days after its twin Voyager 2, Voyager 1 has been operating for 45 years, 10 months and 24 days as of July 29, 2023 UTC [refresh]. It communicates through NASA's Deep Space Network to receive routine commands and to transmit data to Earth. Real-time distance and velocity data is provided by NASA and JPL.
Because the planet orbits so far from Earth, it takes about 248 years to transit through all 12 signs, meaning a Pluto return can't happen for a singular person, explains astrologer Vanessa Hardy. But it can happen for a country that's at least that old, as is the case with the United States this year.
The first crewed Mars Mission, which would include sending astronauts to Mars, orbiting Mars, and a return to Earth, is proposed for the 2030s.
An orbital spaceflight is a different story, with many more risks. I spoke with several former SpaceX employees for this story, and they suspect that Musk probably won't fly to space until he feels that Tesla and SpaceX can do without his personal contributions.
1. Mars Has a Population of Zero. As you probably guessed, there is no known life on Mars.