Here are 10 successful missions by NASA that have made significant contributions to space exploration and science:
1. Pioneer
Launched in 1972 and 1973, respectively, Pioneer 10 and Pioneer 11 were the first spacecraft to visit Jupiter and Saturn, the solar system's most spectacular gas giants. Pioneer 10 was the first spacecraft to pass through the belt of asteroids that surrounds Mars and Jupiter in the solar system.
Around nine months after launch, the spacecraft conducted its first flyby of Jupiter. It captured breathtaking close-ups of the planet's crimson regions and the Great Crimson Spot.
After passing Jupiter almost a year later, Pioneer 11 proceeded to Saturn, where it found two small moons orbiting the planet that had not been previously identified, in addition to a new ring. Both probes have ceased data transmission and continue their one-way trips outside the solar system.
2. Voyager
The Voyager 1 and 2 probes soon followed the Pioneers' flybys. They discovered rings around Jupiter and the existence of volcanism on Jupiter's moon, among other significant findings regarding Saturn and Jupiter. Later, Voyager conducted the first flybys of Neptune, discovering that it weighs less than previously believed, and Uranus, where it detected ten new moons.
The two Voyager spacecraft are investigating the solar system's farthest region and the start of interstellar space. They have sufficient power to continue sending radio signals until at least 2025. At more than 100 times the distance from Earth to the sun and more than twice the distance from Pluto, Voyager 2 is now the furthest man-made object from Earth.
3. WMAP
Though it may not be as well-known, the Wilkinson Microwave Anisotropy Probe (WMAP), launched in 2001, analyses the temperature of the radiation left over from the Big Bang with extraordinary accuracy. By charting variations in the cosmic microwave background radiation, the spacecraft has signalled a breakthrough in our understanding of the structure and age of the universe.
The WMAP measurements proved, among other things, that around 95% of the universe is made up of poorly understood substances known as dark matter and dark energy. They also provided a significantly more accurate estimate of the universe's age—13.7 billion years.
4. Spitzer
The Spitzer Space Telescope is another spacecraft that has significantly impacted cosmology and astrophysics. It used infrared light to survey the skies. The Earth's atmosphere blocks most of this light, which has a longer wavelength than visible light. Besides capturing stunning images of stars, galaxies, and nebulae, the telescope has yielded some significant scientific findings.
Spitzer was the first telescope to detect light from an extrasolar planet in 2005; most of these far-off worlds are only discovered through secondary gravitational impacts on their stars. In a separate finding, scientists speculate that the telescope may have even caught light from some of the universe's earliest stars.
5. Spirit & Opportunity
These workhorse Mars rovers were only supposed to last 90 days, but they have exceeded expectations, Spirit ended its mission in 2011, and Opportunity ended its mission in 2019. The twin Mars Exploration Rovers, Spirit and Opportunity, touched down in January 2004 on different sides of the earth. Ever since, they have traversed the whole surface, peering into craters and meandering across uncharted terrain.
Evidence that liquid water once existed on Mars's surface is one of their most important discoveries. (A nod to Sojourner Rover, which introduced colour close-ups of Mars in 1997, coinciding with the launch of the Internet was growing enormously popular and, as a result, gaining a unique place in the hearts of millions of people who had never before had access to NASA mission images.
6. Cassini-Huygens
Launched in 1997, this joint NASA/ESA spacecraft arrived at Saturn in 2004. Ever since, the spacecraft has been circling the ringed planet, capturing breathtaking images of its rings, moons, and climate.
In 2005, the Huygens probe broke away from Cassini and travelled to Titan, the moon, where it plummeted through the atmosphere and touched down on solid ground. Saturn has been visited by earlier spacecraft, but Cassini is the first to orbit the planet and thoroughly study the system.
7. Chandra
Using X-ray photons, the Chandra X-ray Observatory has been observing some of the most unusual and far-off celestial occurrences since 1999. Astronomers could not observe the universe in this high-energy, short-wavelength light until they launched Chandra into space because Earth's bothersome atmosphere cuts out the majority of X-rays.
Because of its extremely high-resolution mirrors, the observatory can view X-ray sources that are 100 times fainter than any other X-ray telescope. Among other firsts, when Chandra spotted the remnant Cassiopeia A, it gave scientists the first look at the smashed star that remains after a supernova.
8. Viking
The first instance of a man-made item soft landing on Mars occurred in 1976 during the Viking 1 probe's landing by NASA. The Soviet Mars 2 and 3 probes touched the surface, but they malfunctioned immediately.
At six years and 116 days, the Viking 1 lander is also the record holder for the longest-running Mars surface mission. Additionally, the spacecraft sent the first colour images from the Martian surface, giving us our first glimpse of that enigmatic red dot from above.
9. Hubble
The Hubble Space Telescope is the most beloved of all NASA spacecraft, and it has a global reputation. The way regular people perceive themselves in the universe has altered due to its images. Additionally, the observatory has fundamentally altered science by producing too many scientific advances on astronomical problems to count.
NASA created a technology that might ultimately show stars, planets, nebulae, and galaxies in their fully detailed grandeur by launching an optical telescope to look up at the sky beyond Earth's tumultuous atmosphere.
10. Apollo
In addition to being a landmark moment in human history, the Apollo missions were the first to return celestial objects to Earth. They significantly improved our understanding of the moon from a scientific standpoint. Many people (non-scientists, at least) weren't even convinced before Apollo that the moon wasn't made of cheese.
Through in-depth observations of the moon and the subsequent transportation of numerous moon rocks back to Earth, the Apollo astronauts collected data that allowed us to determine the moon's age, composition, and possible formation date.