I recently saw a popular meme that got me thinking; Mars is populated by robots. It sounds like something out of a sci-fi flick, but it’s actually reality. Over 50 years ago, the rest of the solar system was populated by nothing as far as we know. Now, in the name of science and exploration, probes, rovers and landers populate the deepest depths of the solar system. Some of these interplanetary robots have made their homes on various moons, asteroids, and planets. I will highlight some of the most interesting solar system spacecrafts this week.
More rovers have been sent to Mars than any other planet. It’s likely a combination of the planet’s interesting geology, proximity to Earth, and relative ease of successful landing that makes Mars an ideal candidate for space exploration. Scientists also argue that space exploration inspires new technologies in the same way that navigational technology and timekeeping was improved so European explorers could reach Africa, Asia, and the Americas. The incentive of discovery and technological advancement has motivated exploration of Mars since 1960, when the Soviets launched the very first Mars mission.
The Soviet Mars program consisted of multiple attempts to orbit and/or land on the distant red planet with success first coming in 1971, 11 years after the program’s start. After many unsuccessful attempts, underscored by multiple failures to leave Earth, the Mars 2 lander ungracefully became the first manmade object to touch Mars’ surface. It entered the Martian atmosphere incorrectly, causing it to crash and lose contact with Earth. Mars 3 was an identical craft launched 9 days after Mars 2 and made the first soft-landing on Mars. It maintained contact for just 15 seconds before ceasing transmission for unknown reasons. The Soviet’s Mars program ceased after several more unsuccessful attempts.
Viking 1 and 2
NASA fared better in its original exploration of Mars. Inspired by the success of the Mariner program, NASA sent the Viking 1 and 2 landers to Mars in 1975. Both landers reached soil successfully in 1976 and carried out scientific investigations for many years. The Viking 2 lander operated for over 3.5 years before shutting down due to battery failure. The Viking 1 lander, which ran for over 6 years, had its fate sealed by human error; the antenna retracted during a software update and ceased all communication.
NASA’s First Rovers
The US has also famously sent multiple rovers to Mars. Sojourner was the first successful Mars rover, named (like most NASA rovers) through an essay contest won by a 12-year-old from Connecticut. Sojourner means traveler and also alludes to women’s rights activist and abolitionist Sojourner Truth. In 2004, NASA landed Spirit, which converted from a rover to a stationary science laboratory when it became permanently stuck in soft soil. Still, it traveled over 10 times further than anticipated and analyzed Martian geology for 6 years.
The identical rover Opportunity joined Spirit on Mars in 2004 and has been roaming Mars for over 10 years. Its planned activity was 90 Martian days, which means that it will have exceeded its mission time by 10 years at the end of this week (on 04/27/14). As of March 2014, Opportunity has traveled over 38 km, surpassing USSR’s off-Earth driving record once held by the moon rover Lunokhod 2. To give a perspective of Opportunity’s achievement, the surface area of Mars is 144.8 million km2. If Opportunity traveled in 1 km2 areas, it would have to zigzag across mars for nearly 76 million years to cover the entire surface area. (Of course, this is not the purpose of Opportunity, which has been visiting various geological features and collecting scientific data.)
Arguably the most relevant rover, Curiosity landed on Mars in August 2012 and has been characterizing Mars’ climate and geology, investigating evidence of previous life on Mars, and preparing for future human exploration. Nearly a thousand people in Times Square watched Curiosity’s landing and thousands more watched live on NASA’s website. Curiosity engaged auto-pilot for 25 days during a solar conjunction, which is when the Earth and another solar system object are on direct opposite sides of the sun. The solar conjunction greatly hinders radio transmission and, thus, communication with Curiosity was limited.
Over 1.2 million people around the globe sent their names to Mars by having them etched onto a silicon microchip, now installed in Curiosity. It celebrated perhaps the loneliest birthday ever when it played the first song on a foreign planet, Happy Birthday to You, one year after its Martian landing. Curiosity also has its own Twitter feed, where it updates with amazing pictures and new findings in as much detail as 140 characters permits. The rover has nearly completed its 23-month mission and will continue exploring and collecting data after that time period.
Other Space Explorers
Other nations have sent robotic surveyors of their own, including China’s recent landing of Yutu on the moon. Other celestial bodies have been explored, too. The USSR attempted multiple landings on Venus and even placed observation balloons in Venus’ atmosphere. The Cassini mission included the Huygens probe that landed on one of Saturn’s moons, Titan. It was built to last only a couple of minutes but landed softly and collected data for a couple of hours. Rosetta was sent by the European Space Agency to explore comets and will hopefully be the first to land on a comet.
With the success of each mission, space agencies around the world set goals for other objects. The Chandrayaan 2, an India and Russia lunar orbiter and lunar lander, is set to launch in 2015. The design was chosen in a contest where 150 select students submitted design plans. The European Space Agency will send a rover to Mars in 2018. Curiosity is exploring Mars to help plan another Mars mission, possibly as early as 2020. Whatever is in store for the future of space exploration, it remains true that we should continue challenging our technological boundaries and engage in this noble pursuit. After all, it could be someday possible that Mars isn’t just populated by robots.