**1. Introduction**

The study of ancient Mars, as well as its evolution to the planet we can observe today, has become one of the major scientific and technical challenges in the field of planetary exploration. Knowing that Mars was once covered with liquid water, that it had quite an intense geological and volcanic activity, together with the presence of a much denser and rich atmosphere suggest the existence of conditions compatible with the appearance of life, also quite similar to primitive Earth. Considering the vast knowledge we already have about Mars (though probably still a tiny fraction of what is there to learn!), and its accessibility and proximity as our neighbor in the solar system, the study of the red planet is still today the best candidate to look for existing or extant life, or at least to find traces that life might have emerged or existed in those long gone ancient favorable conditions.

It is true that recent studies and discoveries related to the icy moons of the gas giants of the Solar System might present most favorable conditions for past, but also present, existence of life. The evidence of the presence of water liquid oceans below

the icy crust of Europa, or the powerful magnetic field that protects the surface of Ganymede, or Io's intense volcanic activity encourages the idea of considering these Jovian moons as potential life reservoirs. This is also true for the moons of Saturn Titan, with a dense methane atmosphere and a great deal of complex organic molecules; and Enceladus, whose surface is also covered by a thick ice layer. Nevertheless, the technical complexities to reach these planetary bodies, together with very long mission duration make these objectives unreachable today. We will have to wait for the technology and political will to evolve during the following years to ensure the viability of *in situ* missions to these moons in the decades to come.

With these considerations, it is quite clear how the exploration of the Martian surface and shallow subsurface has emerged as the best chance at answering some of the most fundamental questions of humankind: Are we an exceptional fortuity in the Universe, in the galaxy, in the Solar System? Does the appearance of life in our planet answers to a natural process in the evolution of the Universe? In this case, if life or traces of life were to be found in Mars, where there were no plate tectonics and which we know had similar characteristics to primitive Earth, we would be able to study the primal forms of life, forever lost in the ever-recycling Earth mantle.

In this context, this chapter will guide the reader through the evolution of the different payloads used for the exploration of Mars since the kickoff of the space career in the 1960s, providing insights to the technological advances and scientific discoveries achieved, bringing the reader into a time travel into the future of the *in situ* exploration of Mars.

### **2. The pioneering missions**

The timeline of the missions to Mars reflects the evolution of the technical capabilities throughout the history of planetary exploration. This technical evolution, together with the understanding of the planet by previous missions, has helped shaping the increasing complexity of the scientific questions investigated: observation from Earth, fly-bys, orbiters, landers, rovers, etc., which will be followed by helicopters (Mars 2020) and subsurface exploration (ExoMars 2022), missions aimed for the return of Martian samples and finally human exploration and, who knows? maybe the establishment of permanent bases on Mars. Every reached milestone, as will happen with those still to come, allowed to contrast and validate scientific hypothesis formulated about Mars formation and evolution; and also open the door to those questions to be answered by missions to come, especially concerning current habitability hazards.

The pioneering missions acquired great momentum with the Moon space race of the 1960s between the US and the USSR, becoming a renewed Mars competition. As a result, every launch window to reach the red planet became exploited as an attempt to flyby first and then to reach its orbit. Every piece of information or picture about its surface or atmosphere and ambient conditions was considered fundamental for planting the flag first. The race between the Mariner and Mapc projects had started.

#### **2.1 First contact with Mars: Mariner 4 to 7**

Though the USSR launched Mapc 1 in 1963, the first probe ever sent to flyby another planet, it lost the communication when it was at more than 100 million kilometers away from the Earth. This failure cleared the path for the first ever mission ever to fly above Mars to photograph it, the Mariner 4 (1965). This probe,

**91**

mission.

*Evolution of the Scientific Instrumentation for* In Situ *Mars Exploration*

exposed to the solar radiation without any protection.

craters, evidencing water activity on the planet.

equipped with a TV camera threw down all the theories regarding the presence of liquid water on the Martian surface (the astronomers' observations of canals on the late nineteenth and early twentieth centuries were still quite present in the collective memory), confirming the terrestrial observations: a desertic and rocky surface with craters, no oceans, and a very thin atmosphere [1, 2]. However, the images also showed more geologically interesting features than expected. Also surprisingly, the magnetometer onboard the ship did not detect any magnetic field [3]. This, together with the lack of a radiation belt around Mars as confirmed by the trapped radiation detector (TRP) instrument [4], showed that the Marian surface was

These results were surprising at the time, and were of course relevant from an astrobiological perspective, as the preservation of organics and/or life tracers on the Martian surface is surely impaired by the intense and unfiltered radiation. These data were complemented by Mariner 6 and 7, identical probes launched during the 1969 launch window. The aim of these ships was the study of the Martian surface and atmosphere (without any measurements during the cruise phase). To fulfill these objectives, a new instrumentation package was developed, also paving the way for future missions. The Mariner 6 and 7 payloads were included in addition to the

The results of these missions showed a topographically complex surface, where not only the craters reported by Mariner 4 were present but also distinctive topographic forms were observed: chaotic and featureless terrains [5]. These kinds of structures need active modification processes to occur, contrary to a Moon-like crater-only landscape which would imply inactivity since the very old ages. In addition, it was observed how in extreme latitudes ice layers formed in the rim of

With Mariner, infrared spectroscopy showed powerful capabilities as it was used to analyze a wide range of parameters on Mars: polar caps, surface and atmospheric composition, or surface temperature and topography. The results showed that the Martian atmosphere was composed by CO2 with traces of water vapor [6]. On the surface, IR spectrometry detected goethite, an oxidized chemical compound associated with weathering processes in the presence of water. This confirmed for the first time the possibility of a wet ancient Mars. Also, the surface temperature was

Traveling a stable orbit around Mars was a milestone reached virtually at the same time by Mapc 2 and 3, and Mariner 9, all of them launched in 1971. Even if Mapc 2 and 3 departed some days before Mariner 9, a faster cruise phase of the latter allowed it to be the first space probe to orbit another planet by a margin of two weeks. However, the main scientific objectives of Mariner 9 were to continue with the studies of the Martian atmosphere started by Mariner 6 and 7, while mapping the Martian surface. Profiting from the relatively low distance orbit (1600 km, the closest at the time), together with a Visual Imaging System consisting of up to nine cameras with notably better resolution than previous missions (98 vs. 790 m per pixel), Mariner 9 was intended to map 70% of the Martian surface during its

At their arrival to Mars, the probes were greeted by a great sandstorm which lasted for several months. This was of course unforeseeable and had a severe impact in the missions. The soviet orbiters were the most affected, as they were mostly able to photograph the sand clouds above the surface, but the worse was still to come since these missions also included two landers that were liberated for landing as

TV camera, spectrometers in the IR and UV ranges, and an IR radiometer.

measured by the IR radiometer, showing values around 140 K [7].

**2.2 Visiting the planet: first orbits and soft landing**

*DOI: http://dx.doi.org/10.5772/intechopen.93377*

#### *Evolution of the Scientific Instrumentation for* In Situ *Mars Exploration DOI: http://dx.doi.org/10.5772/intechopen.93377*

*Mars Exploration - A Step Forward*

to come.

*situ* exploration of Mars.

**2. The pioneering missions**

ing current habitability hazards.

**2.1 First contact with Mars: Mariner 4 to 7**

projects had started.

the icy crust of Europa, or the powerful magnetic field that protects the surface of Ganymede, or Io's intense volcanic activity encourages the idea of considering these Jovian moons as potential life reservoirs. This is also true for the moons of Saturn Titan, with a dense methane atmosphere and a great deal of complex organic molecules; and Enceladus, whose surface is also covered by a thick ice layer. Nevertheless, the technical complexities to reach these planetary bodies, together with very long mission duration make these objectives unreachable today. We will have to wait for the technology and political will to evolve during the following years to ensure the viability of *in situ* missions to these moons in the decades

With these considerations, it is quite clear how the exploration of the Martian surface and shallow subsurface has emerged as the best chance at answering some of the most fundamental questions of humankind: Are we an exceptional fortuity in the Universe, in the galaxy, in the Solar System? Does the appearance of life in our planet answers to a natural process in the evolution of the Universe? In this case, if life or traces of life were to be found in Mars, where there were no plate tectonics and which we know had similar characteristics to primitive Earth, we would be able to study the primal forms of life, forever lost in the ever-recycling Earth mantle. In this context, this chapter will guide the reader through the evolution of the different payloads used for the exploration of Mars since the kickoff of the space career in the 1960s, providing insights to the technological advances and scientific discoveries achieved, bringing the reader into a time travel into the future of the *in* 

The timeline of the missions to Mars reflects the evolution of the technical capabilities throughout the history of planetary exploration. This technical evolution, together with the understanding of the planet by previous missions, has helped shaping the increasing complexity of the scientific questions investigated: observation from Earth, fly-bys, orbiters, landers, rovers, etc., which will be followed by helicopters (Mars 2020) and subsurface exploration (ExoMars 2022), missions aimed for the return of Martian samples and finally human exploration and, who knows? maybe the establishment of permanent bases on Mars. Every reached milestone, as will happen with those still to come, allowed to contrast and validate scientific hypothesis formulated about Mars formation and evolution; and also open the door to those questions to be answered by missions to come, especially concern-

The pioneering missions acquired great momentum with the Moon space race of the 1960s between the US and the USSR, becoming a renewed Mars competition. As a result, every launch window to reach the red planet became exploited as an attempt to flyby first and then to reach its orbit. Every piece of information or picture about its surface or atmosphere and ambient conditions was considered fundamental for planting the flag first. The race between the Mariner and Mapc

Though the USSR launched Mapc 1 in 1963, the first probe ever sent to flyby another planet, it lost the communication when it was at more than 100 million kilometers away from the Earth. This failure cleared the path for the first ever mission ever to fly above Mars to photograph it, the Mariner 4 (1965). This probe,

**90**

equipped with a TV camera threw down all the theories regarding the presence of liquid water on the Martian surface (the astronomers' observations of canals on the late nineteenth and early twentieth centuries were still quite present in the collective memory), confirming the terrestrial observations: a desertic and rocky surface with craters, no oceans, and a very thin atmosphere [1, 2]. However, the images also showed more geologically interesting features than expected. Also surprisingly, the magnetometer onboard the ship did not detect any magnetic field [3]. This, together with the lack of a radiation belt around Mars as confirmed by the trapped radiation detector (TRP) instrument [4], showed that the Marian surface was exposed to the solar radiation without any protection.

These results were surprising at the time, and were of course relevant from an astrobiological perspective, as the preservation of organics and/or life tracers on the Martian surface is surely impaired by the intense and unfiltered radiation. These data were complemented by Mariner 6 and 7, identical probes launched during the 1969 launch window. The aim of these ships was the study of the Martian surface and atmosphere (without any measurements during the cruise phase). To fulfill these objectives, a new instrumentation package was developed, also paving the way for future missions. The Mariner 6 and 7 payloads were included in addition to the TV camera, spectrometers in the IR and UV ranges, and an IR radiometer.

The results of these missions showed a topographically complex surface, where not only the craters reported by Mariner 4 were present but also distinctive topographic forms were observed: chaotic and featureless terrains [5]. These kinds of structures need active modification processes to occur, contrary to a Moon-like crater-only landscape which would imply inactivity since the very old ages. In addition, it was observed how in extreme latitudes ice layers formed in the rim of craters, evidencing water activity on the planet.

With Mariner, infrared spectroscopy showed powerful capabilities as it was used to analyze a wide range of parameters on Mars: polar caps, surface and atmospheric composition, or surface temperature and topography. The results showed that the Martian atmosphere was composed by CO2 with traces of water vapor [6]. On the surface, IR spectrometry detected goethite, an oxidized chemical compound associated with weathering processes in the presence of water. This confirmed for the first time the possibility of a wet ancient Mars. Also, the surface temperature was measured by the IR radiometer, showing values around 140 K [7].

## **2.2 Visiting the planet: first orbits and soft landing**

Traveling a stable orbit around Mars was a milestone reached virtually at the same time by Mapc 2 and 3, and Mariner 9, all of them launched in 1971. Even if Mapc 2 and 3 departed some days before Mariner 9, a faster cruise phase of the latter allowed it to be the first space probe to orbit another planet by a margin of two weeks. However, the main scientific objectives of Mariner 9 were to continue with the studies of the Martian atmosphere started by Mariner 6 and 7, while mapping the Martian surface. Profiting from the relatively low distance orbit (1600 km, the closest at the time), together with a Visual Imaging System consisting of up to nine cameras with notably better resolution than previous missions (98 vs. 790 m per pixel), Mariner 9 was intended to map 70% of the Martian surface during its mission.

At their arrival to Mars, the probes were greeted by a great sandstorm which lasted for several months. This was of course unforeseeable and had a severe impact in the missions. The soviet orbiters were the most affected, as they were mostly able to photograph the sand clouds above the surface, but the worse was still to come since these missions also included two landers that were liberated for landing as

programmed, suffering the consequences of the storm: Mapc 2 crushed against the Martian surface, while Mapc 3 could certify the first soft landing on the surface of Mars. However, this was a bitter success, as it could only operate during 20 s before (probably) the storm made it lose communications. Mapc 3 was an extremely ambitious mission (probably too much at the time), as it included a small rover, Prop-M, connected with an umbilical cord to the lander platform. The early failure of the mission made impossible to know if the Passability Estimating Vehicle for Mars was successfully deployed on Mars. It took 25 years for a rover to be successfully deployed on the Martian surface.

Instead of that, the US Mariner 9 mission was just an orbiter, but had however one critical advantage compared to their competitors: an onboard patchable software during the mission. This became a mission-saver for Mariner 9, and a space-race win for the US, as the mission ground control modified the plan to save resources during the storm duration and observe the Martian moons in the meanwhile. Once it settled down, Mariner 9 started mapping the Martian surface, sending back to Earth more than 7000 images covering practically 100% of the planet surface. These images showed river basins, huge ancient volcanos, very long canyons, etc., together with evidences of erosion phenomena caused by water and wind [8]. This mapping, together with the confirmation and more precise study of the Martian atmosphere density and pressure, or the surface temperatures with the infrared radiometer (IRR) instrument, allowed the compilation of all the necessary information to prepare, with the maximum possible confidence, the future landing of the Viking missions.
