Spacecraft are vehicles capable of traversing space to other planets or satellites, as well as for other uses, such as communications.
NASA’s Perseverance lander will attempt a landing at Elysium Planitia on Mars’ most challenging region: Elysium Planitia features sand dunes, steep cliffs and boulders – an intimidating destination.
1. Viking 1
NASA scientists in the late 1970s had very limited knowledge about Mars, making it challenging to design spacecraft capable of landing there and accomplishing their missions.
Viking 1 was part of a pair of orbiters and landers launched by a Titan/Centaur rocket on August 20, 1975. The orbiters transported the landers to Mars while also performing reconnaissance to identify potential landing sites as well as serving as communications relays for them.
The Viking Lander was equipped with biological experiments designed to search for signs of life on Mars. These included the pyrolytic release experiment, labeled release experiment and gas exchange experiment. In addition, it carried a gas chromatograph mass spectrometer.
2. Viking 2
Viking 2 launched just three weeks after Viking 1, the second in NASA’s Viking program of orbiters and landers, increasing our knowledge of Mars with high-resolution pictures and performing ambitious chemical experiments to search for life, but unfortunately were unsuccessful in their endeavors.
The two cameras and other instruments on board the lander focused on measuring physical properties of soil and atmosphere such as gas chromatography/mass spectrometry/meteorology/seismology/radiology science as well as studying geology, biology, magnetic properties of the planet itself. Scientists studied all these topics as part of their investigation.
Researchers now suspect that one of the key experiments of the Mars lander’s most important experiment may have been compromised by perchlorate, a chlorine compound present on Mars, as this chemical breaks down to form chloromethane and dichloromethane – chemicals similar to organics that could have had an impact on results of experiment.
3. Spirit
Spirit was part of NASA’s $800 million Mars Exploration Rovers mission and was designed to investigate whether life could have existed on Mars as well as learn about its current and past climate, geology and characterize its geological features.
Golf cart-sized rover Opportunity provided evidence that early Mars was warm and wet – key evidence in the search for life beyond Earth. Unfortunately, however, in 2010 it got stuck in a sand trap and stopped responding to commands sent from JPL.
However, this robot managed to operate for six years, two months and 19 days – more than 25 times longer than originally anticipated. It covered an estimated distance of 4.8 miles while transmitting 128,000 images; scientists believe its longevity may have been increased due to unanticipated events, including wind clearing off dust from its solar panels and prolonging its existence.
4. Opportunity
Spirit and Opportunity were designed for 90-day missions; however, they far surpassed these expectations and set distance records during their travels on Mars. Utilizing cameras, spectrometers, rock-abrasion tools to directly sample its surface, the solar-powered twin robots unearthed clues about past environmental conditions on the Red Planet including signs of water.
The two rovers were sent to Meridiani Planum, where Mars Global Surveyor had noted exposures of the mineral hematite — often formed when exposed to water — through exposures on Mars Global Surveyor’s orbiting camera. There they observed various geologic layers in the region and Opportunity even discovered perchlorate crystals which can reduce freezing point temperature to as little as minus 160 degrees Celsius.
Opportunity made its next stop at Endeavour Crater, exploring rocks indicating water sources for over a year before finally disappearing during a massive global dust storm in June 2018 that blocked sunlight and drastically decreased power levels on Opportunity.
5. Curiosity
Curiosity was the inaugural rover to explore whether Mars ever provided conditions suitable for life to exist on its surface, specifically Gale Crater and its surroundings. This mission is still ongoing.
Landing was an impressive accomplishment, with scientists experiencing an exhilarating seven minutes as the planet’s thin atmosphere started to slow the craft’s forward progress and an aircraft-style sky crane slowly deployed its 1-ton robot onto the surface of Mars.
After its successful campaign in Yellowknife Bay, Curiosity is currently exploring the lower slopes of Mount Sharp (Aeolis Mons). This geological mountain contains layers that help scientists understand how climate has evolved from wetter past periods to today’s dry ones. Furthermore, Curiosity will search for signs of life; should she discover any they could provide proof of ancient life on Mars.