Safely landing robotic explorers on Mars is not easy. The wreckage of crashed U.S., Russian, British, and European Space Agency (ESA) probes litter the Martian landscape. The entry of these unmanned spacecraft into the Martian atmosphere has been aptly called ‘the seven minutes of terror’.
Heat shields, parachutes and retro-rockets must work perfectly starting at about 80 miles altitude to slow down the spacecraft from 12,500 miles per hour to five miles per hour in order to softly touch down.
The InSight Landing
NASA’s InSight lander did precisely that on 26 November on the Martian Surface. The spacecraft will spend at least the next two years studying the geology of the ‘Red Planet’. InSight will be the first robot explorer to study the deep interior of Mars, including its core, crust and mantle.
InSight was launched May 5 by an Atlas V rocket as part of an $850 million NASA mission. It is the latest of a series of Mars landers, rovers, and orbiters that hark back to 1965 as Mariner 4 flew by the planet.
A Brief History of Exploring Mars
But interest in Mars goes back to the dawn of humanity. The ancient stargazers noticed that certain ‘stars’ were not fixed in the sky but moved in specific patterns. We know now that these ‘wanderers,’ or planets, were Mercury, Venus, Mars, Jupiter and Saturn. Later Uranus and Neptune wereadded to this list.
Mars, especially when closer to the Earth, has a definite red hue, which the ancients associated with blood. Thus, the Romans named the planet Mars, after the Roman god of war. The Greeks called the planet Ares, the Greek god of war. The ancient Hebrew word for Mars was Ma’adim or ‘one who blushes (red)’.
The development of powerful telescopes gave astronomers the ability to see Mars as more than just a bright reddish dot. In 1877 Mars was close to Earth and the Italian astronomer Schiaparelli made a series of observations about surface markings, including linear features he described as channels. However, the English translation of ‘canali’ was incorrectly rendered as canals. Thus, the idea of man-made canals was born and given impetus by the writings of American astronomer Percival Lowell, who was convinced there was intelligent life on Mars. This notion became a staple of science fiction.
The first fly-by of Mars in July 1965, by the Mariner 4 spacecraft, put a damper on speculation about dying civilizations or even any life on Mars at all. The spacecraft sent back 22 pictures showing a cratered, almost Moon-like surface, as well as data showing a very thin atmosphere (less than 7 millibars) and very cold ambient temperatures (minus 100 degrees Celsius during the day). These were not very habitable conditions, to say the least… at least not for life as we know it.
As the US space program matured, there was interest in the scientific communityto look more closely for signs of life on Mars. This would require a lander that would safely touch down on the Martian surface with the ability to do biochemical investigations of the surface material.
Project Viking was a program to look for evidence of life on Mars with twin robotic explorers. Viking 1 was launched on 20 August 1975 aboard a powerful Titan III-Centaur rocket. The lander made the first soft touchdown on Mars on 20 July 1976.
Its twin spacecraft, Viking 2, was launched on 9 September 1975.
The orbiters took pictures and measurements while the landers used a mini-chemistry lab to look for signs of life. Viking found evidence of a period in Martian history where there was flowing water and even floods, quite differentthan the bone-dry Mars of today.
The results of the biology experiments were at first thought to be negative for any signs of life. However, later interpretations of the results were more ambiguous due to the discovery in the Martian soil of oxidizing agents such as perchlorates that could have confounded the results. The question of any biological activity on Mars remains an open one over 40 years later.
It would be 20 years until the US again attempted to place a lander on the Martian surface, this time with a small 23-pound rover named Sojourner. The Pathfinder mission was designed to be relatively low-cost. The spacecraft was launched by a Delta II rocket on 4 December 1996, and landed on Mars on 4 July 1997 using a system of parachutes, solid rockets and big airbags.
Sojourner successfully rolled off the main spacecraft, named the Carl Sagan Memorial Station – after the popular astronomer, cosmologist and writer, who had just died – and performed experiments for over 2 1⁄2 months. Extensive data from both the lander and rover were consistent with the theory that water was once abundant on Mars.
Further Journeys to the Red Planet
Later, two rovers were launched to Mars in 2003 as part of the more sophisticated Mars Exploration Rover (MER) program. The first one, named Spirit (MER-A), was launched by a Delta 2 rocket on 10 June 2003. The rover landed on Mars on 4 January 2004 and operated far beyond its design specifications until it got stuck in Martian soil in May 2009. Communications were lost with Spirit in March 2010.
Its twin rover, called Opportunity (MER-B), lifted off on 7 July 2003 and landed on a very flat plain on Mars named Meridiani Planum, on 25 January 2004. The rover had a goal of operating for 90 days but the remarkable vehicle was still active an astounding 14 years later, in 2018, before losing radio contact.
Scientific payloads aboard each rover included four cameras, three spectrometers to measure chemical composition of rocks and soil, a microscopic imager and a rock abrasion tool to allow access to the interior of rocks.
Curiosity, the most recent rover, was sent to Mars on an Atlas V rocket launched on 26 November 2011; it landed on Mars 6 August 2012 in Gale Crater. It was dispatched there as part of the Mars Science Laboratory mission to investigate the climate, radiation environment, geology and presence of water on Mars. Curiosity continues to explore as of 2018, sending back daily photos, climate and atmospheric data, and the results of chemical analyses of rocks and soil.
As InSight studies the interior of Mars, two new rovers will be sent to the ‘Red Planet’ in 2020 by NASA and ESA.
About the Author:
As a 19-year-old college journalist, author David Chudwin covered the launch from Florida in July 1969. Chudwin was the only journalist with official NASA press credentials representing the college press and had extraordinary access to the astronauts, rocket scientists, launch pads, rockets, and control centers.
David Chudwin MD decided to go into medicine instead of journalism, but his Apollo 11 experiences led to a lifelong interest in space exploration. Chudwin has written about Apollo 11 in a variety of media outlets and has spoken about Apollo 11 at schools and at space meetings, including Spacefest. Chudwin is well-known in the space community, and his upcoming book, I Was a Teenage Space Reporter: From Apollo 11 to Our Future in Space, will be published by LID in Spring 2019.