Which Planets Have We Visited Or Explored?

Have you ever wondered what it would be like to live on another planet? Whether you’d live on Mercury or Mars this article is for you! We’ve covered the most important planets in our solar system from Mars to Neptune. But which other planets have we visited or explored? Here are a few of them. And don’t forget to add your own favorite. There are still many planets to discover.


While many people dream of visiting the red planet the fact remains that humans have never been there. Since its discovery in 1961 nine spacecraft have been sent to Mars but none has been successful. Several of these missions have failed either at launch or while burning in interplanetary orbit. The United States Russian Federation and Indian Space Research Organization are the only countries that have sent spacecraft to the red planet.

Scientists hope to learn more about the origin of life on Mars. NASA missions have sought to collect information about the composition of different objects in the solar system. They have studied the composition of surface materials and the atmosphere of the planet. The rover will look for biosignatures such as mineral structures associated with living organisms and organic molecules modified by biological processes. Mars may have even harbored extraterrestrial life.

The United States will send its fifth rover to Mars the most advanced probe ever sent by NASA. The mission will carry an infrared spectrometer and a visible-light camera. These instruments will help scientists better understand Mars’ atmosphere and other features such as its climate and oceans. In addition to the Mars 2020 rover China will also send a robotic emissary to Mars in 2025.

India launches its first Mars mission the MAVEN craft on its second attempt. The mission will land on Mars on 18 February 2021. The Chinese launch their own Mars mission Tianwen-1 a deep-space probe named after the quest for heavenly truth. Tianwen-1 aims to examine the atmosphere of Mars and detect evidence of life. The mission is still a ways off but it’s a significant first step.

The human exploration of Mars is a long-term goal with manned missions to the red planet taking anywhere from 10 to 30 years. Humans can get to the Moon in about a week but they need about eight months to travel to Mars. Meanwhile the International Space Station has been busy studying space adaptation which will help us survive on Mars once we arrive there. However there is no timetable for humans to visit Mars and the first manned missions may not be completed until the 2030s.


Throughout the last century many spacecraft have been launched to explore Venus. Nasa’s Pioneer Venus mission and the Soviet Union’s Venera missions have each carried instruments to explore the planet. The Pioneer Venus orbiter carried a radar altimeter that produced medium-resolution radar images of Venus’ equatorial region. The Pioneer-Venus bus carried four scientific instruments that measured the atmosphere surface temperatures and pressure.

Early radar observations of Venus’ surface stimulated interest in its geology. These images showed that Venus had a more compact surface than the Moon but showed bright highlands called tesserae (equivalent to continents on Earth). The Soviets’ subsequent Venera 8 mission landed on the planet on July 22 1972 and also relayed data from the surface to Earth. Their observations of Venus’ atmosphere and weather caused scientists to refine their models of the planet’s geology.

NASA’s DAVINCI mission is set to launch in the late 2020s and will carry a probe to the planet’s surface. During its hour-long descent the probe will collect thousands of measurements and up-close images of its surface. While it may not survive its landing will provide bonus science. ESA’s EnVision mission is another detailed mission to Venus. The European Space Agency (ESA) is a partner and has already sent a lander to the planet but NASA is providing its own high-resolution radar for the mission.

Another mission planned for Venus is called VERITAS. It will carry a state-of-the-art radar system that will create a high-resolution map of the planet’s surface. It will also produce 3-D topographic charts showing individual volcanoes and fault systems. The map will be updated continuously allowing scientists to explore the planet’s interior. If this mission is successful it will allow humans to make use of its new technologies.

A proposal by the European Space Agency and NASA for a Venus Flagship mission to the planet has been approved. The two missions are considered the first major missions to Venus since the 1990s. Only one probe is currently orbiting Venus – Japan’s Akatsuki spacecraft. It is studying the planet’s atmosphere and surface and ESA’s Hakan Svedhem a former project scientist of Venus Express helped prepare the proposal for approval.


As a distant icy dwarf planet Neptune is not an easy target for human exploration. Its orbit around the sun is far from Earth and its gravitational pull keeps it from being an attractive target for humans. Nevertheless scientists continue to push for human exploration of Neptune which is 29 AU from Earth. The orbital distance of the dwarf planet is roughly 30 times that of the Sun. The orbital distance of Neptune limits robotic exploration to this icy world.

Among the most interesting things about Neptune is its moon Triton. The seventh-largest moon in the solar system Triton is unlike any other body in the solar system. Scientists suspect that the moon formed in the Kuiper Belt a vast field of icy objects from the early solar system. Triton has an unusual orbit which means it is offset from Neptune’s equator by 23 degrees.

Voyager 2 flew past Neptune in 1989 and it observed the planet’s atmosphere continuously from June to October of that year. The Voyager 2 discovered six new moons and a large storm which confirmed that Neptune does indeed have rings. Other details of Neptune’s atmosphere were uncovered through the use of dedicated missions. These missions will further explore Neptune’s atmosphere and ejected particles from the planet.

If you’re interested in learning more about Neptune you can check out some of the many articles and news releases published by NASA. And if you’re feeling a little overwhelmed by all the information out there you can also check out the Solar System Exploration Guide to Neptune. And if you want to learn more about Neptune visit Astronomy Today NASA’s Hubblesite and the Hubble Space Telescope.

As mentioned Voyager 2 flew past Neptune during its Grand Tour of the Solar System. It passed within 3000 km of its north pole. This made it the closest object to Earth since its launch. If you’re wondering if Neptune has been explored by astronauts or visited here are some interesting facts about the planet and its moons. Consider taking a trip there!


Mercury has not yet been explored by astronauts. However there were flybys of Mercury made by Mariner 10 in 1973 and 1974. Mercury is closest to Earth than Jupiter Saturn or Pluto making it difficult to study from Earth. The proximity also made the astronomical body extremely hot presenting challenges to engineers and scientists and further delaying the mission. Even if it could be studied from Earth Mercury’s proximity to the Sun and low magnetic field made it difficult to study the planet.

A spacecraft called BepiColombo is currently preparing for a flyby of Mercury. The European Space Agency launched it in 2018 and the spacecraft won’t slow down for orbital insertion until December 2025. The mission is scheduled to begin its primary science mission on Mercury in early 2026. During the early days of space exploration Mercury received comparatively little attention. In the early 19th century the newly invented telescopes of Galileo and Thomas Harriott allowed scientists to observe Mercury by crossing the face of the Sun. However astronomers thought Mercury always faced the Sun so they incorrectly assumed that it was always facing the Sun. Nevertheless radar discovered that Mercury rotated three times in two orbits. In the same year the Mariner 10 spacecraft took pictures of Mercury’s surface during its three flybys.

The MESSENGER spacecraft was the first spacecraft to orbit Mercury in 2006. The mission’s purpose was to study the metallic core of the planet. The orbit of Mercury is unstable because of its proximity to the Sun. Consequently the spacecraft will have to travel at a high speed to reach the icy planet. But the BepiColombo mission is a crucial step in the exploration of Mercury.

Although Mercury is the smallest planet in our solar system the planet has been visited by astronauts twice. In 2004 the Mariner 10 and Messenger space probes were launched. They will eventually orbit Mercury in 2011. The Messenger probe’s picture of Mercury was sent back to earth in 2008 demonstrating that it is an amazing place to explore. A closer approach to Mercury is difficult and astronauts would have to wear spacesuits to stay warm.