History of UAS: Exploration of Mars

            Since the inception of space exploration, the United States and other countries have sent space probes and rovers to Mars. There have been forty-three explorations to Mars since 1960.  The first by the USSR, and the most recent by India (Historical log, n.d.).  This study will look at two programs from the United States, Mariner and Mars Science Laboratory. The first commenced pre-1970 and the second is ongoing. The initial Mars exploration probes from the Mariner program were simple robotic systems with a few sensors.  The current Mars Science Laboratory (MSL) is a very robust program, which includes the rover, Curiosity and the Mars Reconnaissance Orbiter. There are similarities, as well as, significant differences between these programs.

            This study will provide a brief introduction of the Mariner and MSL.  It will include a comparison between the unmanned vehicle used in these programs, highlight the differences, and provide rational of the design changes that occurred in both programs.  A discussion on new technology that may influence future evolution of the design and capability will be provided.

Mariner

            The Mariner program was designed to investigate Mars, Venus and Mercury.  The program commenced in 1962 with the launch of Mariner 1 and 2.  The first vehicle failed at launch and the second was sent to Venus, where NASA tested communications systems for future programs and provided radiometric temperature measurements.  In all, NASA had ten Mariner probes. With the exception of the first two, Mariner 5 (Venus), and Mariner 10 (Venus and Mercury), the focus of the missions was the exploration of Mars.  The program terminated in 1973 after seven successful missions (Historical log, n.d.; Mariner to Mercury, 1996). 

            The Mariner probes that went to Mars initially flew by the planet taking pictures and taking samples and measurements.  The sensors were able to measure cosmic dust, solar plasma, radiation, and magnetic fields.  The probes communicated directly back to earth using low rate transmission systems, requiring the use of data error correction codes.  By the ninth mission, the probe was designed to orbit Mars for almost a year, mapping and taking measurements (Mariner to Mercury, 1996). 

            During this period in history, USSR was also launching multiple probes to Mars.  In total, they launched six systems, two were successful.  Their Mars 3 and 6 programs included a rover that landed on Mars, but failed to produce useful data (Historical log, n.d).

Mars Science Laboratory

            The Mars Science Laboratory (MSL) mission is part of NASA’s Mars Exploration Program, a long-term robotic exploration of the planet to determine a landing site for future habitability. The program also includes the study of water, climate and geology of Mars. This program is highlighted by the most advance robotic system in space, the Curiosity rover.  Curiosity is the largest most advanced robotic operated vehicle with multiple sensors, supported by a robust communications architecture. 

Curiosity

            Curiosity weighs over 2,000 pounds, moves up to 295 feet per hour, and can roll over large obstacles. It is powered by a radioisotope power system that will provide it a full Martian year (687 Earth days) or more.  This provides greater operational flexibility and ability to travel greater ranges than past rovers. The sensor array is quite remarkable. It has thirteen main sensor systems that samples and analyzes the environment.  Curiosity has seventeen cameras, numerous probes and samplers, and two computer systems, which support the collection, storing and transmitting the data to earth (Mars Science Laboratory, n.d.).

            The rover is supported by two satellites revolving around the planet, the Mars Reconnaissance Orbiter and the 2001 Mars Odyssey Orbiter. The later initially supported previous Mars exploration programs.  The rover can rely data to the orbiters, which then transmit at higher data rates to NASA’s Deep Space Network satellites orbiting Earth.  Additionally, these communications paths allow for data to be transmitted when the rover is not in direct sight to earth.  The rover is capable of receiving and transmitting data directly to Earth at low data rates via the X Band Small Deep Space Transponder (Mars Science Laboratory, n.d.).

Mars Reconnaissance Orbiter

            The Mars Reconnaissance Orbiter that supports Curiosity also serves a probe.  It has an experimental camera that has increased the amount of imagery obtain from the planet tenfold. The information obtained from camera system will allow NASA to pick future landing sites.  The camera system has taken imagery that is used to analysis the surface of Mars for the presence of water (Mars Reconnaissance Orbiter, n.d.)

Comparison

            While technology advances have allowed for more complex space exploration programs, the basic program elements are similar.  From the initial design, launch, and operations, programs prior to 1970 are similar to those being launched today. The design challenges posed by the extreme radiation exposure problems are the same, as is the physical challenges to get the unmanned systems in space.  The electronic components need to be designed to meet the physical extremes of the actual launch to the operation in deep space. 

            Equally difficult is the communications challenges posed by the great distances.  It takes approximately 14 minutes to transmit a signal to Mars, and another 14 minutes to receive a reply (Time delay, 2012).  Even though the bandwidth is significantly more with modern communications architecture that leverages satellites as relays, these delays pose the same challenges today as they did in the pre-1970 programs.   

            Mariner was the first Mars exploration program developed by the United States.  To mitigate risk, it consistent of small probes, each capable of taking measurements that advanced their knowledge for the subsequent mission.  The success of this space exploration program lead to the Mars Science Laboratory that is exploring Mars today.

            In comparison to current space exploration systems, the initial Mariner probes were very small. Their missions were designed for short duration of a few months to a year or two.  A few of the probes lasted beyond their design life, and transmitted useful information back to earth for three years (Mariner, 1996).  Their sensor arrays were mostly limited to remote sensing.  Due to the limited computer capabilities and bandwidth of the communication systems, the sampling and measurements were fairly basic compared to those of the MSL.

            The MSL program is a complex, robust, and evolving program.  As the name implies, it is a science laboratory, which comprises of both the orbiter and rover.  The combined solution allows for both remote sensing as the orbiter goes around the planet, as well as specific sampling of the landing site.  Multiple experiments occur every day and changes to the experiments can occur within days.  This is in contrast where the Mariner probes were programed well before launch and minimal changes occurred throughout the missions.  Mariner 4 took a total of 21 images, Mariner 7 took 126 images, and Mariner 9 took 7329 images. On the other hand, sensor technology and communication systems now allow for hundreds of images and sensor information to be transmitted daily.

Future Design and Capabilities

            The Mars Science Laboratory utilizes twelve cameras and artificial intelligence for navigation. However, Curiosity only moves on average 30 meters a day. Each movement is analyzed by engineers and scientist at the Jet Propulsion Laboratory in Pasadena and other facilities around the world.  It is an arduous process to ensure the safe navigation of the rover (Mars Science Laboratory, n.d.).

            Significant technological advancements in the past few years seen in autonomous vehicles have application for the space rovers.  The combination of artificial intelligence, neural network and behavioral analysis with computer vision has allowed for autonomous or assisted driving.  These improvements will not only be applied to future space programs, but also for the current Mars program.  Although, Curiosity does not have a LiDAR like most autonomous vehicles of today, the use of computer vision with the twelve cameras could allow for advancing the use of autonomous technologies in the current system.  The addition of LiDAR type sensors to future rovers, will allow for a more robust navigational system that will allow for more autonomous operation of these systems.

            While NASA put a lot risk in the deployment of Curiosity as a one rover program, going back to using multiple vehicles, like the ten Mariner probes may be a better option in the future.  With the developments in nano technologies, advanced computers, and algorithms, future programs could deploy multiple rovers at the same time, being able to cover much more areas.  Some of the rover could be designed with aerial capabilities with a balloon, multi-rotor or fixed wing systems.  They would be able to access areas that ground vehicle can’t do.  Some of these unmanned systems could be long-term vehicles such as Curiosity, while other be dispensable low cost sensor packages. In essence, it is a combination of the Mariner probes with the advancement made in the Mars Science Laboratory program.

References

Historical Log. (n.d.). Retrieved August 14, 2016, from http://mars.nasa.gov/programmissions/missions/log/

Howell, E. (2016, May 13). Mars Curiosity: Facts and Information. Retrieved August 14, 2016, from http://www.space.com/17963-mars-curiosity.html

Mariner to Mercury, Venus and Mars [PDF]. (1996, May). Pasadena, CA: California Institute of Technology.

Mars Reconnaissance Orbiter-Overview. (n.d.). Retrieved August 14, 2016, from http://mars.nasa.gov/mro/mission/overview/

Mars Science Laboratory - Overview. (n.d.). Retrieved August 14, 2016, from http://mars.jpl.nasa.gov/msl/mission/overview/

Time delay between Mars and Earth. (2012, May 05). Retrieved August 14, 2016, from http://blogs.esa.int/mex/2012/08/05/time-delay-between-mars-and-earth/