The twin Spirit and Opportunity rovers enjoyed long and successful missions since 2004 on opposite sides of our neighbor planet, Mars. While Spirit got stuck in soft sand in 2009 and stopped communicating about a year later, Opportunity continues to operate, well exceeding its planned 90 Martian day mission by (to date) over ten years.
Mars. See the related link for more information.
Mars.
Opportunity was designed to explore Mars. Launched in 2003, it was part of NASA's Mars Exploration Rover Mission and aimed to study the planet's geology and search for signs of past water. The rover operated for nearly 15 years, far exceeding its initial 90-day mission, and provided valuable data about the Martian surface and environment.
You can go places and explore.
john William has explored the planet mercury... but no one has been sent out to this planet
It explored Mars.
He Explored Jupiter and its moons
New horizans
As there are no planets (new or old) close enough for astronauts to explore, this cannot be answered.
Spirit and Opportunity rovers explored the planet Mars. They were part of NASA's Mars Exploration Rover mission, landing on Mars in 2004 with the goal of studying the planet's geology and searching for evidence of past water activity.
space station
The planet closest to Earth is Venus. We can explore Venus, and we have sent multiple spacecraft to study its atmosphere and surface. However, its extreme temperatures, atmospheric pressure, and acidic environment make it challenging for human exploration.