Probes That Landed Successfully On Mars
Mars is the most explored planet in our Solar System for obvious reasons. First, Mars is the closest of all the planets in our neighborhood when its closest distance ever recorded was a mere 54 million kilometers (36 million miles) apart in 2003. Second, it is the only planet which show signs of being habitable millions of years of ago with evidence that water once flowed freely there. Because of its proximity to us Mars has been visited by many space probes in the last five decades with the vast majority of them ending in disaster. It is no easy matter to get something from here to there where only seven of the more than 30 probes sent there; flybys, orbiters and landers, landed successfully on the surface. Many of them failed in transit, other failed while in orbit and some simply crashed during landing. The space probes we will discuss here are the ones sent to Mars that landed successfully and went on to complete their mission sending back critical data to help scientist plan for possible future manned space flights to Mars.
A Little History About Mars Space Probes
The early space probes sent by the Soviet Union, now Russia, through the Mars and Zond Programs in 1960s to the late 1970s and by the United States in mid1970s were generally camera equipped only. They were sent just to take pictures of the Martian surface as flybys. In other words, these probes were send to Mars to take a few photos as they flew by Mars and kept going further into the Solar System until somewhere along the way they met their demise. Their mission were to photograph potential landing sites for future landers.
By 1969 the design of the space probes sent to Mars by the Mars Program became a little more sophisticated with the addition of maneuvering thrusters to park them into orbit around Mars to take considerably more pictures of the surface. They also were basically two parts spacecrafts, one part served as an orbiter and the other part as a lander. By this time photos of the two moons of Mars, Phobos and Deimos, were also captured with the newly designed spacecrafts. The controversial “Last Photo” was taken in the late 1980s with the Phobos 2 orbiter before its failed in the final stage of its mission. There were speculations that a large UFO about 25 kilometers in size caused the failure but was later dropped.
The addition of the thrusters on the spacecraft gave scientists the flexibility of placing these probes at various latitudes, specifically over the polar and equatorial region of the planet. Furthermore, the lander made it possible to place a probe on the surface but unfortunately many of the initial attempts ended in failure. It will be a while before Russia finally land one on the surface to become the first to accomplish this feat in 1971.
The Mars Program launched 12 probes to Mars in the 60s and 70s with six of those attempts made in 1964 with all of them ending in failure. However, the Soviets managed to get one to Mars in 1963 and landed another one on the surface of Mars in 1974, but they both eventually failed thus ending the Mars Program in 1979. They sent two more probes to Mars under the Zond and Phobos programs which also ended in failures due to communication problems. Russia made one final attempt in 1996 under the Russian Space Forces to launch a spacecraft to Mars, but the spacecraft ended up in an Earth orbit. In the end Russia launched a total of 16 probes over the years that in ended in failures. As a result, Russia did not launched another spacecraft, the "Phobos-Grunt", to Mars until November 2011 and ironically it too ended in a disastrous Earth orbit.
NASA on the other hand, did not start sending probes to Mars until 1976 and continued to send them until 2003. Mariner 4 was the first spacecraft sent by the United States to reach Mars in 1964 and the U.S. did not put a probe on Mars' surface until the Vikings probes landed successfully in 1976. In the end NASA would launched a total of 14 probes to Mars with a few failures along the way but they ended up being more successful than Russia in sending them there. Currently, there is spacecraft named "Curiosity" which recently landed on Mars. It became the largest robotic rover ever placed on the Mars surface after an eight month flight to get there.
Mars Up Close: Inside Curiosity Mission
The Marvelous Eight
Despite the large number of probes sent to Mars by the Soviet Union and the United States only seven of them landed successfully on the Martian surface. Soviet Union managed to claim the honor of being the first to land a probe on Mars in 1971 and it would be another 5 years before the United States finally land one on Mars. Here is the list of the eight Mars space probes that landed successfully on the surface by both countries between 1971 through 2012. They are Mars 3, Viking 1 and Viking 2, Sojourner, Spirit, Opportunity, Phoenix and Curiosity.
The Mars 3 probe was the only one successfully landed by the Soviet Union as mentioned earlier while the remaining seven were from the United States despite the fact that the Soviet had a head start in the race to sent a probe to Mars. Furthermore, the United States landed its first probe successfully on the Martian surface on their very first attempt of sending one there.
The Mars 3 probe was one of the earliest two-component spacecraft and the first to land on Mars in December 1971. It had a component called the "orbiter" which remained in orbit after the separation of the second component called the "lander" which eventually descent to the surface. The orbiter served two purposes. First it took photos of the surface and secondly, it functioned as communication relay for the lander on the surface. The orbiter also measured atmosphere temperature and geophysical properties of the planet such as temperature, solar radiation, magnetic field, etc. The lander at the time only took photos at the surface, but unfortunately after touchdown in the tropical region of Mars the lander only functioned for a brief 20 seconds sending back only one very grainy photo of the surface. It was believed a dust storm knocked it out of service.
However, the orbiter continued to function until August 1972 sending back 60 images of Mars but at a poor resolution due to transmission and resolution problems. It was designed to send back 480 images.
Viking 1 & Viking 2
The Viking probes were the first spacecrafts consisting of an orbiter and lander sent to Mars by the United States. Viking 1 and Viking 2 landed in the tropical region of Mars on July 1976 and September 1976, respectively. Incredibly both landers landed successfully on the martian surface in the first attempt of sending a probe to Mars by the United States. The probes were very successful in completing their respective missions. They would send back some of the best photos of the Mars' surface and images from it orbiters while revolving around the planet. Some of these photos contained images of geological features such as volcanoes, canyons, lava plains, and craters taken on the surface. NASA would officially end the communication to the two probes in November 1982 and April 1980 for Viking 1 and Viking 2, respectively since they had essentially completed their mission objectives.
Sojourner was part of the Mars Pathfinder spacecraft sent to Mars on December 1996 about 20 years after the last successful landing of a spacecraft on Mars with the Viking spacecrafts. The spacecraft consisted of two parts a lander and a small rover carried on board. No orbiter were involved in this mission due to improvements in communication technology since the last lander was placed on Mars.
The spacecraft landed on the surface of Mars on July 4, 1997, completely enclosed in inflated airbags to cushion the impact by bouncing around until it came to a complete stop and the airbags deflated immediately after stopping. The rover was deployed a day later from the Pathfinder lander to begin its series of experiments on the soil. On that day Sojourner became the first machine to move from one location to another on Mars and the second one on another planet or moon. Russia successfully landed the first rover on the Moon back in the 1970s.
The rover was a six-wheeled machine weighing just 25 pounds named after the black Civil War abolitionist Sojourner Truth. During it three month mission the lander sent back 16,500 photo and made 8.5 million measurements on the characteristics of the martian atmosphere, namely atmospheric pressure, temperature and wind speed while the rover during that same time period sent back 550 photos with chemical analysis data gathered from 16 different locations. Communication to the rover ended on September 1997, two month beyond it intended duration.
Spirit & Opportunity
Spirit and Opportunity were twin rovers sent to Mars in 2004 and landed on the surface the same way Sojourner landed with inflated airbags seven years earlier. Their 90 day mission was to search for and analysis clues on the surface of Mars for past water activities such as formation of certain salt deposits and mineral deposits left behind after water evaporation, frozen water beneath the soil, signs of erosion, etc.
The rovers were essentially the same design as Sojourner with six wheels but it had a more developed 3-D viewing camera, more sophisticated set of analytical equipments and an included drilling mechanism for drilling into rocks to gather sample from the interior of the rocks. With all the instruments on board these rovers each weighed 400 pounds and were capable of traveling 300 feet per day with the electrical power generated and stored from their large solar panels.
After 90 days, the rovers continued to function for about 5 years and 7 years for Spirit and Opportunity, respectively. Opportunity is still functioning as of this writing. Spirit stopped communicating on March 22, 2010, but scientists still have hope that it will re-awake at some point in the future.
Despite a few minor setbacks during their highly successful mission, Spirit and Opportunity have sent back a combined total of 260,000 images and a galore of scientific information from Mars while traveling 5 miles and 20 miles over the surface, respectively. All this information will keep scientists busy for many years to come. Recently, the rovers were awarded the "Popular Mechanics Lifetime Achievement Award" for their extraordinary achievement on their mission.
Phoenix was the last of the spacecrafts to land on Mars successfully using twelve thrusters to slow its descent to the Martian surface. It became the first probe to land near the polar region, basically at the edge of it in June 2008. All the previous probes had landed in the tropics of Mars. The main objective of the mission was to study the soil chemistry for evidence of water, nutrients and energy sources for organisms.
The probe has found two very important chemical components in the soil: calcium carbonate and perchlorate. Calcium carbonate forms when atmospheric carbon dioxide dissolves in water vapors in the air and rain forming carbonic acid. When the rain reaches the soil, the acid dissolve the calcium found in the soil to form calcium carbonate which is the chemical name for the common substance on Earth called limestone or chalk. This chemical is a strong indication that Mars may at one time had a thicker atmosphere to produce the rain to create all the signs of erosions and river flows along with the ancient lake beds observed on the planet.
Perchlorate is a chemical found in the very arid regions on Earth and it has been observed to be a nutrient for desert bacteria. Phoenix has found perchlorate in the soil on Mars and scientists are speculating that there may be microbes in the soil similar to those on Earth that consume perchlorate as nutrients. So there appear to be a possibility that there might be microbial life on Mars.
The Phoenix mission lasted five months and ended in November of 2008 before the winter season settled in bringing frigid weather and darkness to the polar region. The last image taken by the orbiter the following spring showed the lander on its side with a broken solar panel.
Curiosity recently became the latest spacecraft to successfully land on Mars on August 6, 2012, (early morning, eastern daylight saving time in eastern United States) in a crater called "Gale Crater". Scientists believe a lake may have once been there. This rover is the largest ever to land successfully on Mars after surviving a nail-biting descent the NASA team dubbed "Seven Minutes of Terror". It mission is to determine if Mars was once a habitable planet by looking for evidence of specific organic molecules indicative of previous life if it was once there. This mission is planned to last for the next two years.
Curiosity's Mission on Mars
© 2011 Melvin Porter
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