Curiosity is an innate urge in human nature. When explorers discovered the new world, thousands flocked to explore it out of curiosity. We are on the cusp of great exploration, the planets in our solar system have started to be explored, starting with Mars. Mars has captured the attention of astronomers for centuries. In ancient times, the Greeks thought of Mars as the god of war due to its red tint. Mars had been thrust into the spotlight once again and is seen as the next step for space exploration. As such, numerous space agencies have done missions to Mars over the years and the colonization of Mars is predicted to occur in the near future. The development of these space probes has changed greatly over the years starting with the first space probes sent to Mars.
The Soviet Union launched the 1M No. 1, 1M No.2, 2MV-4 No.1, and Mars 1 space probes from 1960-1962, which all ended in failure. All of these probes used a Molniya L1-4M rocket which was derived from the R-7 series of rockets and was originally used to make Intercontinental Ballistic Missiles. These rockets have enough thrust to clear Earth’s orbit and have been modified to serve as carrier rockets for most Soviet space probes launched in the 20th century. The early versions of space probes were powered by 42 ampere-hour cadmium-nickel batteries and two solar panel wings. These solar panels varied in size but were usually 28 sq ft. This provided enough power for the probe to communicate and store a bit of excess for when the need arises. For communication, a 1.7 m (5.6 ft) parabolic high gain antenna was used, as well as an omnidirectional antenna and a semi-directional antenna. These antennas were the only thing that made communication with the probe possible. These spacecraft carried various scientific instruments with them to study the composition of Mars’ atmosphere, radiation levels, and a plethora of other things when they got to their destination. The Mars 1M No. 1 carried a radiation detector, cosmic-ray telescope, Television imaging system, and a spectral reflectometer. Cosmic ray telescopes measure the energy and direction of protons and alpha particles. The television imaging system allowed the probe to take and send pictures of Mars back to Earth.
NASA launched a few of its own missions later on in the decade which included a majority of the 10-mission Mariner program. These probes had the goal of reaching Mars and exploring its different features. This was done in a series of flybys and one successful orbit done by the Mariner probes. These probes set the groundwork for later missions ran by NASA.
The Mariner 4 completed the first successful flyby of Mars in 1964. The Mariner series of probes were launched on Atlas rockets, which are American expendable missiles. The first few of probes were powered by 28, 224 solar cells contained in four 176 x 90 cm solar panels. These solar panels can provide 310 watts of power near Mars and the excess is put into a rechargeable 1200 W-h silver-zinc battery. The solar panels were improved in the later versions, such as the Mariner 7, to provide 449 watts when near Mars and 800 watts on Earth. The difference in power generation comes from decreased sunlight due to the increased distance from the sun. The farther you are from the sun, the less concentrated the sun light becomes. The Mariner 4 was a pioneer in using a star as a navigational object instead of the Earth. The probe used the star Cannopus as a navigational reference point on its flyby of Mars. This allowed the probe to travel on course without being in view of Earth, which meant that longer voyages would be made possible by this technology.
The Mariner 9 was the first spacecraft to orbit another planet. This feat was accomplished in 1971 and narrowly beat the Soviets by weeks with their launch of Mars 2 and 3. The Mariner orbiter took thousands of photos of Mars’ surface and revealed many of Mars geological features such as its huge volcanoes, winding canyons, and sporadic craters. The Mariner 9 used an Atlas Centaur-D rocket because it was significantly heavier than its Mariner counterparts. It weighed 997.7 kg on launch which was more than double than what the 411 kg Mariner 7 weighed. The Mariner 9 used a vastly improved imaging system when compared to its predecessors. The Mariner 9 was able to record a resolution of 320 feet per pixel, which is leagues ahead of the 2,600 feet per pixel of the past. This jump in resolution greatly improved the image quality captured by the orbiter and helped in identifying key structures from the Mars landscape. Some of these structures include the Olympus Mons, the Valles Marineris, and various other geological qualities.
The Soviet Union also sent a few space probes of their own during the early 70s, such as the Mars programs which consisted of 8 missions with the sole goal of exploring Mars. Out of these 8 missions, only 2 were successful,the Mars 2 and 3 orbiters. The Mars 2 probe was made up of an orbiter and a lander which weighed tons more than their American equivalents. The combined weight of both the lander and orbiter was 4,650 kg at launch compared to the 997 kg from the Mariner 9. The lander failed to safely land on Mars but the orbiter managed to successfully orbit Mars and study the planet within its orbit. The orbiter had been outfitted with various scientific instruments, the newest one of which was the ultraviolet spectrometer. This allowed the probe to measure the electromagnetic radiation that was present on Mars. The orbiter also found that surface temperatures on Mars range from -110 ℃ to 13 ℃, the surface pressure of Mars, and its water vapor content.
NASA launched the Viking program which was made up of the Viking 1 and 2 missions in 1975. The main goal of this program was to search for life on Mars and explore more of Mars using landers and orbiters. The twin orbiters were equipped with VIS cameras, thermal sensors, and MAWD sensors used to map water vapor. The landers used pressure, temperature, and density sensors on landing. The Viking lander used honeycomb aluminum shock absorbers to absorb the landing, which were much lighter and stronger than their iron predecessors. An 18-nozzle design was used with the landing rockets so the surrounding environment remained undisturbed, which would be needed for the experiments run by the Viking lander. The lander was able to take panoramic pictures of Mars and set up a relay link with the orbiter to send data over 10 times faster than a direct link. The landers had a few positive results in the experiments but nothing concrete was found about the existence of life on Mars.
After nearly 2 decades without any new spacecraft, NASA launched the Mars Global Surveyor in 1996. The goal of the Mars Global surveyor was to globally map the entire planet of Mars. The surveyor also helped rovers find new sites to explore later on in its life. The Global Surveyor was outfitted with a Mars Orbiter Camera(MOC). The MOC was composed of 3 instruments: A narrow high resolution camera(1.5 to 12 m per pixel), a colored wide angle camera(230 m per pixel), and a daily global imager(3.1 to 7.5 km per pixel). Delta II rockets were used to launch the 1,000 kg Mars Global Surveyor into space. The Delta II rockets differ from Atlas rockets in that the Delta can handle a heavier payload without straining under the load. The Mars Global Surveyor had an alternative way to generate power. Solar panels need a direct line of sight to the sun to produce electricity, so if the spacecraft is behind a planet or in deep space, the spacecraft would be powerless. Another option for power generation takes advantage of the heat generated by radioactive decay and can provide power for years while taking up very little space. They employ radioactive materials such as Plutonium and Uranium to produce heat and convert this heat into energy. This is known as radioisotope power systems(RTG) and has been used in a variety of NASA missions for the last 5 decades, such as Apollo 11, Curiosity Mars rover, and the Cassini probe.
In pursuit of clarification surrounding the existence of water/ice on Mars, NASA launches the 2001 Mars Odyssey. Delta II rockets were used to launch the 758 kg orbiter into space. The three primary instruments used by the Odyssey were: Thermal Emission Imaging System(THEMIS), the Gamma Ray Spectrometer(GRS), and the Mars Radiation Environment Experiment(MARIE). THEMIS is a camera that images Mars in infrared and determines what the ground is made of by the frequency of the feedback.. This can be used to determine whether there is ice beneath the ground and what the polar regions are composed of. GRS returns information about Mars topography, which is especially useful for rovers so they know where they are going. MARIE measures the radiation in the environment and determines whether it would be safe for a human.
After the turn of the millenia, ESA started to send out missions of its own to Mars. The first of which was the Mars Express. The orbiter had an aluminum honeycomb pattern for its body and two 20 m long dipole antennas. The spacecraft was powered by 11.42 square meters of solar panels made from silicon cells, which produce 660 W. Power is stored in three lithium-ion batteries with the capacity to store 64.8 Ah, which is used during solar eclipses. Telecommunications for this orbiter is composed of 3 antennas, a parabolic high gain antenna and 2 omnidirectional antennas. The antennas open channels to the Earth control center and sends data through them as well. ESA was just getting started in its space program, so great things are to be expected.
NASA let a public university, the University of Arizona, lead the Phoenix Mission in 2008. The Phoenix had two main missions; to study the history of water on Mars and to evaluate the potential for life to be present in the ice-soil. Power would have to be generated from two gallium arsenide solar panels(75 sq. ft) and the Nickel-Hydrogen battery would have enough storage for 16 Ah. A RAD6000 based computer system would be installed on the lander for easier computations. The 350 kg lander was one of the last spacecraft to launch on a Delta II rocket. University of Arizona installed improved versions of the Mars Polar Lander Camera on the Phoenix. In addition, experiments that had previously been canceled were loaded onto the Phoenix such as wet chemistry experiments and a robotic arm that took samples of soil. These experiments would give us new insight on the inner workings of Mars.
In 2014, India surprised the world by launching the Mars Orbiter. While the orbiter was mainly a means to display new technology, but its other main objective was to study the effects of solar wind and radiation to Mars upper atmosphere. The 1,137 kg orbiter used a MAR31750 processor in its maneuvering system along with two star sensors and four reaction wheels. The spacecraft was powered by 3 solar panel arrays(81.4 sq. ft) which produced a maximum of 840 watts of power. The excess was stored in a 36 Ah Lithium-Ion battery, where it was used incase of a solar eclipse. In communication, the Mars Orbiter used a high, medium, and low gain antenna. This allowed for three separate channels for data exchange to occur and data transfer between mission control and the orbiter was smoother than a 2 channel connection.
In recent years, more countries have started to send space probes to Mars and explore its surrounding moons. Some examples of these nations are Japan, India, and China. More people are looking at space as the final frontier and want to be at the forefront of this modern movement. Space probes have developed from rudimentary rockets to amazing feats of human engineering. This change happened over time and nobody could have foreseen what has been accomplished with these probes. The entirety of the surface of Mars has been mapped out and its many secrets have been uncovered. Mars is currently in the spotlight of space exploration, but other planets can also rise to the prominence of Mars in due time.