Credit: NASA – Van Allen Probe

Some space probes make a fly by, getting near a space object. Others are called orbiters, that go into orbit around a space object such as a planet or moon. Landers make a touchdown on the surface of a space object and rovers are designed to move on the surface.

Many successful flyby’s took place to space objects such as Venus, Mercury, Jupiter, Saturn, Uranus and Neptune. Several orbiters visited Venus and Mars, landers have reached the moon, Venus, Mars, Saturn’s moon – Titan, asteroids Eros and Itokawa and comer Churyumov – Gerasimenko. Rovers have explored the surface of the Moon and Mars.

• In 1962, Mariner 2 was the first successful planetary probe and flew past Venus.
• In 1965, Mariner 4 got the first close-up images of Mars .
• In 1972, Pioneer 10 flew past Jupiter, studied its radiation and magnetic field and discovered its liquid interior before heading out of the solar system.
• In 1973, Pioneer 10 flew past Jupiter and Saturn.
• In 1974, Mariner 10 flew by Mercury and Venus. It was also the first spacecraft to use the gravitational pull of one planet (Venus) to reach another (Mercury), and the first spacecraft mission to visit two planets.
• In 1976, USA’s Viking 1 and 2 landed on Mars and returned images of the surface.
• In 1979, Pioneer 11 was the first to visit Saturn.
• Voyager 1 and 2 were sent to study the outer Solar System. Voyager 1 made the historic entry into interstellar space, the region between stars, filled with material ejected by the death of nearby stars millions of years ago. Voyager 2 passed by Jupiter in 1979, Saturn in 1981, Uranus in 1986, Neptune in 1989 and entered interstellar space in 2018. Both voyagers used the “slingshot” effect to hurl them over from Jupiter’s gravity towards Saturn.
• In 1985, the International Cometary Explorer (ICE) made the first flyby of a comet, and passed by Giacobini–Zinner.
• In 1991,  the Galileo space probe made the first flyby of asteroids, which imaged both 951 Gaspra (in 1991) and 243 Ida (in 1993) on its way to Jupiter.
• In 1997, US Sojourner was the first Mars Rover.
• In 2015, the New Horizon Probe flew by Pluto.

Probes with missions to explore distant space objects save fuel using the “slingshot” theory. Probes may use a nearby planet gravity to catapult them on their way, such as the Mariner 10.

Most space probes are not designed to return to Earth. Some probes are still in space sending data to mankind. For example current active missions incude:

• Voyager 1 and 2 launched in 1977 are in interstellar space and expected to beam back data past 2020 as they travel out of the solar system.
• The Pioneers 10 and 11 are now at the edge of the Solar system and may reach the vicinity of the Star Aldebran in about 2 million years.

Probes continue in space unless they collide with a piece of space object.

Article adapted from Encyclopedia of Space, by Miles Kelly