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Table of Contents
Abstract .................................................................................................................................................. 2 I. Introduction ......................................................................................................................................... 3 II. Mars Odyssey Overview and Missions ................................................................................................. 3 III. Launch Vehicles .................................................................................................................................. 4 IV. Aerobraking........................................................................................................................................ 5 V. Instruments ......................................................................................................................................... 6 1. Thermal Emission Imaging System (THEMIS) ................................................................................ 6 2. Gamma Ray Spectrometer (GRS) .................................................................................................. 7 3. The Mars Radiation Environment Experiment (MARIE) ................................................................. 7 VI. Results ............................................................................................................................................... 8 VII. Legacy ............................................................................................................................................... 8 VII. Reference Page ............................................................................................................................... 10

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Abstract
With all the suspects and preliminary evidences that show life existence on Mars, NASA’s Mars Exploration Program has revealed numerous pieces of vital information with one of its mission, Mars Odyssey. This research paper will provide a thorough information of the early stage development of the mission, preparation for launching the spacecraft, technologies used to achieve the goals, and the results of the mission. The information in this research paper is mainly obtained from various online resources. With all the information provided, one may have more understanding about the process of exploring Mars as well as the result that scientists have collected from the Mars Odyssey exploration program.

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I. Introduction
Humanity’s creativity is endless. We are always driven to push the boundaries of technology’s limits. It is amazing how far we have come when we look back at the evolution of the human race. With the technology, we always have a desire to explore every unknown matters such as exploring life in the deep ocean, or finding a way to cure cancer, etc. There is one biggest mysterious matter in the universe that we are eager to discover: the Universe. Life in outer space has been a controversial topic for decades. Given how vast, or even indefinite, the universe is, there must be somewhere out there that contains life’s conditions like Earth, and all of the greatest scientists are trying to explore a planet right in our solar system that seems to have evidence of life existence, Mars. This paper will fully cover all the essential information about one of many missions in the NASA’s Mars Exploration Program, Mars Odyssey. The information will include the early stage development of the mission, spacecraft, devices, as well as all the technologies used in the Mars Odyssey.

II. Mars Odyssey Overview and Missions
A lot of scientific missions have shown that Mars has a similar in characteristic and development history compared to Earth. Mars exploration started in the beginning of late 20th century when The Union of Soviet Socialist Republics (USSR) launched the Mars probe Marsnik 1; but it failed to reach Earth orbit. Over the time, with the development of more advanced technology, human race are getting closer to finding the evidences that will confirm the existence of water and other elements that support life on the surface of Mars. One of the biggest project that serve the purpose of Mars exploration was Mars Odyssey, which was started in 2001. Mars Odyssey was a costly project developed by National Aeronautics and Space Administration (NASA) with an expected cost of US$297 million. “2001” Mars Odyssey” was used for the project as a tribute to the science fiction author Arthur C. Clarke. In the project, a spacecraft was developed and sent to Mars orbit carrying special devices, which will me mentioned in detail later in this research paper, to achieve three main goals. According to “Mars Odyssey: Mission” by NASA, the first goal is to determine if life ever arose on Mars. According to scientists, all life on Earth require water to survive and evolve. There has been evidence that water exists on the surface of Mars so it is likely that there has been life on Mars. Odyssey will be searching for evidence of liquid water on and below the Martian surface at a global scale so scientists can further studies about the

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theory of life existence on Mars. Other than water, scientists also look for energy sources on Mars other than sunlight. The reason is because there are life exists on Earth at places that does not have sunlight like under the ocean, caves, underground so there might be something similar on Mars. All signs of biosignatures of current and past life will also be looked for. Scientists understand that life form outside Earth can be totally different so the main challenge is to differentiate between life and nonlife matter on Mars. The second goal that NASA want to achieve is to characterize the climate of Mars. It is extremely crucial to extend our knowledge about Mars’ climate characteristics in the past and its changes over time. The reason is because once scientists fully understand the Martian climate, they can maps how Mars behaves during each particular period in a year and questions about Martian planet changes over years can be answered. Based on current studies, Martian weather is known with a lot of large scale dust storms occur in the southern spring and summer. In times the storm can grow to surround the whole Martian planet. The third and final goal is to characterize the geology of Mars. Having information about the age of rocks and deposits on Martian surface allows geologists to understand more about landform events of Mars. More importantly, some minerals are formed in the presence water only, which lead to evidence of life on Mars. The Mars Odyssey also serves as a relay communication for future Mars exploration program. 2001 Mars Odyssey launched on April 07, 2001. After 200 days of interplanetary cruise, it enters Martian orbit on October 24, 2001.

III. Launch Vehicles
Odyssey was launched at 11:02 a.m. on April 7, 2001 on Delta II 7925, a part of the Delta rocket line which is developed by Boeing. Delta II uses nine strap-on solid rocket motors; and the measurement of each motors is 1 meter in diameter and 13 meters long. The launch vehicle is divided into three main stages. The first stage of the vehicle is where the Rock LR101-NA-11 vernier engines is placed. Along with the engines that control roll and altitude, the first stage also carries almost a hundred thousand kilograms of RP-1 propellant, which is a more refined form of kerosene, with oxygen acts as an oxidizer. “Delta Overview” by Boeing provides all the procedures need to be taken after launching the vehicle. After the first stage is separated, the vehicle will be powered by a AJ10-118K engine mounted in the second stage with 24 meters in diameter and 6 meters long with 6000 kilograms of Aerozine 50 fuel. Aerozine 50 fuel is the mixture of half hydrazine and dimethyl hydrazine.

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The third and the last stage is called PAM-D, where the Mars Odyssey is placed, will send the spacecraft to Mars orbit. There is a spin table to stabilize the spacecraft during the separation process from the second stage. During the ascent of Delta II through Earth’s atmosphere, air friction may damage the PAM-D so there is a 2.9 meter diameter payload fairing to protect the PAM-D.

IV. Aerobraking
Aerobraking is a spaceflight maneuver technique that allows the spacecraft to enter and lower its orbital altitude. Aerobraking works by having the spacecraft to brush against the top of the planet’s atmosphere. The solar panels are used to increase the maximum drag to slow down the spacecraft; it also provides control when the spacecraft is entering the atmosphere. Aerobraking is extremely difficult to execute because it requires precise navigation, a good understanding of the planetary atmosphere and how will the force impact the spacecraft. “The successful completion of the aerobraking phase is a major milestone for the project. Aerobraking is the most complex phase of the entire mission and the team came through it without a hitch,” said David A. Spencer, Odyssey’s mission manager at Jet Propulsion Laboratory (JPL). The reason why aerobraking was employs for the mission was because using this technique could save cost. Odyssey used the upper atmosphere of Mars to slowdown rather than using its thrusters, hence resulting in a saving of more than 200 kilograms of propellant. By reducing the mass of the load, NASA was able to fit the spacecraft into a smaller launch vehicle, the Delta II 7925, instead of using a larger and more expensive launch vehicle. There are three main phases during the aerobraking process: walk-in, the main phase, and walk-out. The walk-in phase is during the first hour to eight when the spacecraft arrives Mars orbit. Engineers on Earth uses the behaviors of Odyssey in and out of aerobraking to calibrate. Basically the walk-in phase is used to test if the studies and assumption of scientists about Martian atmosphere is accurate. There are a lot of vigorous activities happen on Mars such as dust storm; and it seriously posts a thread for the aerobraking process because the storms would affect the height and density of the atmosphere. This is when the THEMIS comes in to detect any dust storm activity as well as to monitor the atmosphere on Mars prior to the aerobraking process. Once Odyssey’s distance to Mars has been lowered to about 100 kilometers, the main aerobraking phase begins. During this phase, Odyssey skimmed through (specific term is ‘drag passes’) the upper layer atmosphere of Mars for more than 300 times in 78 days. The spacecraft’s altitude is reduce for every passes make by Odyssey. Any necessary

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adjustments are made if Odyssey is flying either too low or too high. Radio transmitter is also turned off to conserve energy during the pass. And the solar panels on Odyssey are securely used to brush the Martian atmosphere, hence resulting in increase the maximum drag. Before doing that, Odyssey has already oriented itself to point the solar panels downward. The walk-out phase happens during the few final days of the aerobraking process. Onboard thrusters will be activated to achieve the final 400 kilometers circular science orbit.

V. Instruments
In order to achieve the goal of the mission, Odyssey carries three instruments to the Mar’s orbit. They are Thermal Emission Imaging System (THEMIS), Gamma Ray Spectrometer (GRS), and Mars Radiation Environment Experiment (MARIE). All of the three innovative technologies use spectrometers to collect data. Reference 2 states that spectrometers are used to detect all the information of the electromagnetic spectrum that is invisible to human’s eye. Electromagnetic spectrum is the range of all electromagnetic radiation with different wavelength frequencies. Visible lights that we see every day is only one of the seven different frequencies of the electromagnetic spectrum. The other six are radio wave, microwave, infrared, ultraviolet, x-ray, and gamma ray. All of those require the aid of machine in order for us to view it. Spectrometers device will map all the light with different wavelengths into a spectra, which is a rainbow-like bars, and scientists can use the emission and absorption lines to detect and exist atoms.

1. Thermal Emission Imaging System (THEMIS) As aforementioned, all three instruments involve in the use of spectrometers. The Thermal Emission Imaging System (THEMIS), which weights 11.2 kilograms with dimension of 54.5 centimeters by 37 centimeters by 28.6 centimeters, uses infrared to map the distribution of minerals on Mars surface. The way the THEMIS works is it maps all the reflected heat from minerals on Mars surface during the day. Each minerals’ heat reflection has its own characteristic so that THEMIS can identify the minerals base on the heat reflection. The reason THEMIS is able to detect different materials based on the heat emission is because each geological materials has different colors on the infrared spectrum. By finding the specific material’s presence on Mars, researchers can confirm if water has ever exist on Mars surface. Additionally, THEMIS usage of multi-spectral also provides information of hydrothermal and subsurface water deposits for further research. Since THEMIS device maps heat, it is able to detect all the heat source on Mars surface at night on

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Mars so scientists can research about activities that happen on the surface. Other than using infrared, this instrument is also capable of mapping image using visible light with resolution of 18 meter for geology studies. The THEMIS instrument is also used to select an ideal landing site for the Mars Science Laboratory (MSL) project, which successfully landed Mars rover Curiosity on November, 2011.

2. Gamma Ray Spectrometer (GRS) The second instrument that Odyssey carries is Gamma Ray Spectrometer (GRS). It weighs 30.5 kilograms with the dimensions of 46.8 centimeters by 53.4 centimeters by 60.4 centimeters. As the name suggests, GRS uses gamma ray and two neutron detectors to map the distribution of all the elements that make up the Martian surface. According to NASA, the devices has four main components and they are the gamma sensor head, the neutron spectrometer, the high energy neutron detector, and the central electronics assemble. The reason why GRS is used for this purpose is because it is capable of detecting elements of the periodic table like hydrogen, chlorine, iron, etc.

The way GRS works is that it detects all the unique signature energy emits by different elements when they are exposed to cosmic ray from other stars, particularly the sun. GRS device allows scientists to know how elements are distributed, and how abundant they are on Mars; thus lead to further understanding of the origin and the development of its geology. The GRS also serves an important role of detecting hydrogen on Mars, which indicates water presence, by measuring neutrons.

3. The Mars Radiation Environment Experiment (MARIE) The Mars Radiation Environment Experiment weighs 3.3 kilogram with dimensions of 29.4 centimeters by 23.2 centimeters by 10.8 centimeters. MARIE starts collecting data right when it leaves Earth, and continues to do so on its journey to Mars. A spectrometers inside MARIE measures all the energy from many radiation sources such as the sun, stars within and outside of our solar system. It is crucial to gather radiation data because radiation is extremely hazardous to our human bodies. Long exposure of radiation can cause cancer and damage central nerves system. Scientists need all of these data to prepare to minimize the risk of radiation exposure for astronauts in future space exploration programs.

There was a problem with MARIE on October 28, 2003 when there was a large solar event impacted the Odyssey spacecraft. Engineers believe that the computer chip was damaged during the event and MARIE has failed to gather more information since then. At

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the end of 2005, engineers attempted to reactivate MARIE again after enough time of recovery.

VI. Results
After its arrival, Odyssey’s first result is in shortly and it shows that there is a lot of ice concentration on Mars. The GRS instrument detects a large amount of ice within one meter of the surface around the south pole of the red planet. The GRS actually does not detect water, but it detects the existence of hydrogen within the first layer of the surface. This evidence strengthens the beliefs that water has been existed on the Martian surface. "The preliminary assessment of the gamma-ray spectrometer data indicates the likely presence of hydrogen in the upper few feet of the Martian surface, as sampled at spatial scales approximately 400 miles across," said Jim Garvin, lead scientist of NASA's Mars exploration program, in a statement. Scientists also receive good news from the THEMIS device with a lot of crisp and clear images of the Martian surface. “The diversity we see here is really striking,” Philip Christensen, the principal investigator of THEMIS, said. “This will truly allow us to peer into the dark recesses of Mars.” With THEMIS, scientists have been able to map the distribution of olivine-rich materials on Mars. Olivine is a common green volcanic mineral that breaks down rapidly in contact with water. THEMIS images provide geologic context for these materials, first identified by Mars Global Surveyor's Thermal Emission Spectrometer (TES) instrument (according to “Discoveries” by Mars Odyssey THEMIS website). From that result, scientists believe that Mars has complex volcanic processes. All of these information is extremely crucial for us to know more about the planet that is most likely to have life existence. As mentioned earlier, the MARIE device suffered a damage from a solar event and engineers have not been able to make it run again. However, MARIE is actually able to send back the data about radiation exposure on the journey to Mars. It shows that the radiation astronauts would receive while going to Mars is twice as the amount they would receive while working on the International Space Station (ISS).

VII. Legacy
“Mars Odyssey: Record-Breaking Mission to Mars”, by Elizabeth Howell, reports that Mars Odyssey broke the record in 2010 for being the longest-serving machine at Mars for more than a decade. Odyssey spacecraft plays an important role as a relay communication

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for Martian rovers including Spirit (2003), Opportunity (2003), and Curiosity (2011). Until now, Odyssey still continues to send valuable images as well as information from other working Martian rovers.

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VII. Reference Page
Reference 1. “Delta Overview” Boeing. Internet. Retrieved on March 3, 2014. Available: http://www.boeing.com/boeing/defense-space/space/delta/delta2/delta2.page

Reference 2. “Mars Odyssey: Mission” NASA. Internet. Retrieved on March 2, 2014. Available: http://mars.jpl.nasa.gov/odyssey/mission/overview/

Reference 3. “Mars Odyssey: Record-Breaking Mission to Mars” by Elizabeth Howell. October 29, 2012. Available: http://www.space.com/18270-mars-odyssey.html

Reference 4. “Mars Odyssey Arrives” by J. Kelly Beatty. June 25, 2004. Available: http://www.skyandtelescope.com/news/3304426.html

Reference 5. “NASA Mars Orbiters See Clues to Possible Water Flows” NASA. Internet. Retrieved on March 5, 2014. Available: http://mars.jpl.nasa.gov/odyssey/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1599.

Reference 6. “Discoveries” Mars Odyssey THEMIS. Internet. Retrieved on May 7, 2014. Available: http://themis.asu.edu/discoveries