5 of the Greatest Missions in Space Exploration History

When it comes to the exploration of the final frontier, many people think of the moon landing as by far the greatest achievement ever made, but there have been many truly incredible feats of engineering in space exploration history, including those that have taken us to the furthest reaches of the solar system and beyond. Unfortunately, they have all failed to garner the same level of cultural impact on the general public as the moon landings. Nonetheless, when you consider just what has been achieved by the following missions, you can start to grasp the far greater extent of what we know about space than what we did just a few decades ago.

Pioneer Space Probes, 1972

NASA

An artist’s impression of Pioneer 10 approaching Jupiter in November, 1973. It would still be another 30 years until NASA finally received the last signal from the probe.

Pioneer 10 and 11 were part of the long and highly successful Pioneer program, which lasted from 1958 to 1978. They were the first ever space exploration missions to the outer solar system. Pioneer 10 was launched in March, 1972 and its near-identical sister space probe, Pioneer 11 was launched in April, 1973.

Little was known about the outer planets until Pioneer 10 and 11 took the first ever close-up images of Jupiter and, in the case of Pioneer 11, Saturn as well. These two probes ended up having some of the longest missions ever by the time NASA finally lost contact with them in January, 2003 and September, 1995 respectively.

The Pioneer probes leave behind an impressive legacy, having kick-started the exploration of the outer planets. Pioneer 10 reached Jupiter after a year and a half of traveling, taking the first ever close-up photos of the planet. It also took photos of Jupiter’s four Galilean moons Io, Europa, Ganymede and Callisto. Pioneer 11 enjoyed an even greater degree of success, taking detailed images of some of Jupiter’s most significant features, such as the 200-year old Great Red Spot cyclone. Using a gravity assist from Jupiter to boost its speed, Pioneer 11 ventured onward to Saturn, taking the first ever photos of the ringed planet in 1979. Today, the two probes now continue towards interstellar space at tens of thousands of miles per hour.

Voyager Space Probes, 1977

NASA

This crescent view of Jupiter was taken by NASA’s Voyager 1 on Mar. 24, 1979.

The Voyager space probes are the longest-running space exploration missions so far. Voyager 1 was launched in September, 1977 and its sister spacecraft, Voyager 2, was launched a month earlier. The Voyager program was one of the most successful ever and continues to this day to send data over the countless millions of miles back to Earth.

The Voyager probes were launched to take advantage of what at the time was a favourable alignment between the planets, greatly decreasing the length of the journey. They were sent to learn more about the outer planets, including Neptune and Uranus, which had remained largely shrouded in mystery up until then.

Voyager 1 arrived at Jupiter in 1979, taking detailed photos of the planet and the four Galilean moons before heading to Saturn with the help of a gravity assist from the gas giant. It arrived at Saturn a year later, taking photos of the planet and the first ever photos of many of its larger moons including Mimas, Tethys and Titan. It was Voyager 1 that finally confirmed the uniqueness of Titan – the only moon in the solar system with anything more than a trace atmosphere.

Voyager 2 also explored Jupiter and Saturn before becoming the first and, so far, the only space probe to explore Uranus and Neptune up close. It took close-up photos of both planets and many of their moons, some of which were discovered for the first time by the probe.

Both Voyager 1 and 2 are still operating and broadcasting signals back to Earth. Today, Voyager 1 is the most distant man-made object from Earth and the first ever to reach interstellar space. Voyager 2 is also heading towards the heliopause (the edge of the Solar System). Both probes continue to head out into the lonely depths of space at around 38,000 and 35,000 mph (61,150 and 56,330 kph) respectively. They will continue for millions of years and will likely exist, floating through the void between stars, long after life on Earth has ceased to exist.

Hubble Space Telescope, 1990

NASA

Although representing only a tiny region of the observable universe, the famous Hubble Ultra-Deep Field photo composite contains around 10,000 galaxies, some of which are as old as 13-billion years.

Much closer to home is the Hubble Space Telescope in low Earth orbit. Without light pollution and atmospheric interference, Hubble looks into the most distant depths of the observable universe and tells us about the history of everything that ever existed. It explores galaxies so far away that light from them has taken billions of years to reach us, effectively allowing us to look back in time to when the universe was young.

Hubble was taken by space shuttle into orbit in April, 1990 and remains in service. Hubble is unique in that it is serviceable by astronauts, allowing it to be upgraded and repaired with relative ease. It is due to remain in orbit for up to another eight years. The last servicing mission took place in 2009 when Hubble received some powerful new upgrades including a new wide field camera and spectrograph.

Hubble is famous for the numerous stunning photos it has taken of deep space. In fact, many of the most famous astronomy photos ever taken come from Hubble, such as the Hubble Extreme Deep Field photo showing a colourful montage of distant galaxies millions of light-years from Earth and the beautiful photo of the Eagle Nebula, dubbed the Pillars of Creation. One of NASA’s greatest achievements to date, the Hubble Space Telescope continues, with its upgraded hardware, to probe the most distant edges of the universe to learn more about the theory of everything.

Cassini-Huygens Space Probe, 1997

NASA

A view of Titan taken by the Cassini-Huygens probe when it arrived in the Saturnian system in 2004. In the foreground, are Saturn’s rings and Epimetheus, one of its inner moons.

Since the confirmed discovery of Titan’s unique status as the only moon with an atmosphere by Voyager 1 in 1980, astronomers have been profoundly excited to learn more about this alien world. Cassini-Huygens was launched in 1997 and inserted into Saturn’s orbit in 2004. It was also the only space probe to launch a landing module onto the surface of one of the outer astronomical bodies.

Cassini-Huygens passed by Jupiter in December, 2000, taking many photos and scientific readings before heading on to its ultimate destination, Saturn. The probe discovered a number of new minor moons orbiting the planet. The main purpose of the mission was to learn more about the atmosphere and surface features of Titan, one of the largest moons in the solar system and some fifty percent wider than our own moon.

What really made Cassini-Huygens special was the Huygens landing module, provided by the European Space Agency. Using atmospheric breaking, the Huygens probe made a successful and gentle touchdown on the freezing surface of Titan, taking the first ever surface photos of an astronomical body beyond Mars. It continued to send back scientific data and photos for some ninety minutes, using its mother-ship to relay data to Earth.

The lander discovered much about the mysterious world of Titan, and Cassini-Huygens continues to do so with many more flybys of the moon planned. Thanks to this mission, we now know that Titan is the only other world in the solar system confirmed to have stable bodies of liquid on the surface, albeit in the form of liquid methane and ethane rather than water. In December, 2012, the probe even discovered a Nile-like river flowing with liquid ethane on the surface. Cassini-Huygens is set to continue its mission until 2017.

Mars Science Laboratory, 2011

NASA

The surface of Mars, taken in 2013 by the Curiosity Rover. This region was chosen as the rover’s first drilling site.

One of NASA’s greatest achievements to date is undoubtedly that of the Mars Science Laboratory, most famous for its Mars rover, Curiosity. It is thanks to remotely controlled rovers such as this that we now know more about the surface of Mars than the bottom of the Earth’s oceans. We have photos of Mars that look as though some was walking there in person taking pictures with a high-definition camera.

The Mars Science Laboratory is to investigate Mars in search for the building blocks of life and learn more about its geology and geochemistry. The car-sized Curiosity rover landed on the barren Martian surface on August 6, 2012. The landing was a moment of unspeakable tension in the NASA control centre back on Earth. After a journey of 350 million miles, Curiosity was released by the Mars Science Laboratory and entered the Martian atmosphere at 12,400 miles per hour. The rover had seven minutes to decelerate and touch down gently on the Martian surface. NASA control then had to wait for another thirteen minutes for the first signals to cross the millions of miles back to Earth. And those first signals showed that Curiosity, after its truly epic journey, had reached its destination safely.

The Curiosity rover, powered by a nuclear battery, will continue to explore the surface of Mars, using its extensive array of cutting-edge technologies, for several years. It has taken the most stunning panoramic photos of the red planet that we’ve ever seen. Back on Earth, scientists send it commands, telling it where to go and what to do with its instruments. The long delay make it impossible to control the rover in real-time, so Curiosity also needs to use its own on-board computers to navigate carefully. Hazard avoidance cameras help to ensure that it does not go near any potentially harmful objects as it moves extremely slowly and carefully across the Martian terrain. The rover is also equipped with hardware used to cut into rocks and analyse them using its on-board laboratory.

Glenelg Crater is the rover’s ultimate destination, where it will learn more about Mars’s geological history and the compounds that make up its surface. If life has ever existed on Mars or even still exists in some basic form today, then there’s a good chance that Curiosity and upcoming missions will discover it.