Chapter Number and Title

1.1 Rover

1.1.1 Mission Design - Masaaki Atsuta The requirement of our mission is to collect at least 10 kg of samples such as rocks and soils from the surface on Mars. After touchdown, the stowed Rover deploys the antennas, raises the mast and releases the arms. Then, the astronauts on the spaceship communicate with the Rover and perform a health check. After the health check, the Rover ventures out from the Lander and begins a one (Earth) year journey on the Martian surface. When the astronauts find a candidate for the samples, they command the Rover to approach the target and to analyze it by using its science instruments. Once they find samples interesting enough to return to Earth, the Rover picks it up and delivers it to a Radiation Detector. Only when the Radiation Detector determines that the sample is not harmful to people, the Rover puts it into the Sample Container. Once the Rover houses the sample in the Sample Container, it starts on its way home. When the Rover gets to the Sample Return Vehicle, it rolls up the ramp and puts the container inside the vehicle. After the Rover takes a shower to sterilize itself and replaces a new Sample Container, it rolls down the ramp and leaves for the next adventure. During 365 Earth days, our Rover plans to take about 100 round trips within the radius of 1 km from the Lander and must document and collect a set of samples consisting different types of rocks and soils and ensure at least 10 kg of sample mass.

1.1.2 Design Specifics

1.1.2.1 Structure - Masaaki Atsuta As we can see in Figure 1, our Rover is almost identical to its predecessor, a Mars Exploration Rover (MER). The size of the Rover is also similar to that of the MER, about 150 kg in mass, 1.2 m long, 1.0 m wide, and 0.7 m tall with its mast deployed. Like the MER, the Rover has six wheels and two pairs of cameras perched on the end of the long neck. r e v o R

AAE 450 Senior Spacecraft Design Spring 2004 . 1 1 e r u g i F Chapter Number and Title

AAE 450 Senior Spacecraft Design Spring 2004 2 Chapter Number and Title

Despite the appearance, our Rover is more powerful and sophisticated than the MER. The Rover uses a Radioisotope Power System so that it can handle its 365 Earth-day mission on the Marian surface, showing a dramatic increase over the 90 Martian-day (92 Earth-days) life of the solar-powered MER. The Rover’s body covers electronic components with a Warm Electronics Box (WEB) insulted with a high-tech material aerogel. The Rover has two identical robotic arms. The right arm is for Science Interments: a Raman Spectrometer, Alpha Proton X-ray Spectrometer (APXS), and Microscopic Imager. The left arm is for Sample Collection Tools: a Parallel Gripper and Scoop.

1.1.2.2 Rover Design - Masaaki Atsuta The Rover for our mission must meet the following requirements: 1) The Rover must collect Martian samples of at least 10 kg and put them to the Sample Return Vehicle (SRV). 2) The development cost must be as low as possible. 3) The Rover must run for 365 Earth days. To meet the first requirement, our Rover needs an arm to precisely place its robotic hand to grasp samples. At the same time, the Rover needs an arm to bring heavy Science Instruments close to or on the samples to analyze them. So, our Rover has two arms: the left arm for Sample Collection Tools and the right arm for Science Instruments. The left arm can smoothly move a light-weight Sample Collection Tool such as a Parallel Gripper and Scoop to a target, while the right arm can carry a heavy but sophisticated Science Instrument. The arms themselves are identical and have three joints, a Shoulder Joint, Elbow Joint and Wrist Joint. We design the wrist joint at the end of each arm to be especially flexible. The handy joint can grasp Sample Collection Tools or Science Instruments and twist them vertically and horizontally to position them precisely to a target. Also, to make sure that samples that the Rover brings back to the SRV don’t cause any biohazards, we equip our Rover with a Radiation Detector and a Sample Container. The Radiation Detector measures the dose of radioactivity in samples and forces the Rover to deposit any samples beyond the limit indicating that they “may be dangerous to people” onto the surface.

The Sample Container covers a sample with a Biobarrier made by Tyvek ® (a fiber sheet to protect against bacteria and viruses) and Planova ® (a virus removal filter).1, 2, 3, 4 To keep costs down, we can use as many elements as past successful missions as possible. Also, the use of proven hardware increases the reliability of a Rover. In fact, NASA plans to use a Mars Exploration Rover 2003 class rover with the capability to collect rocks for their first Mars Sample Return Rover Mission.5 So, we borrow many components from the MER. To keep a Rover alive for a year on Mars, our Rover uses a Radioisotope Power System (Supply) as its main power source. A Solar Power System, a traditional rover power source, is not enough for our mission because dust accumulation on the solar panels limits, for example, the life of the MER to about 90 days. But, a Radioisotope Power System may survive more than 10 years. The Viking Landers 1 and 2 used this power system and they had functioned for six years until the last lander was shut down. (We expect that it can last for 14 years). Besides, the power production is independent of the day / night cycle and the distance from the Sun.6 NASA has also considered Radioisotope Power Supplies as a power system option for their 2009 Mars Science Laboratory Mission, which plans to operate a full Martian year (687 Earth days).7, 8

1.1.2.3 Components - Masaaki Atsuta Our Rover uses 44 brushless EC motors. These long service life motors can function in Mars’ low-temperature, low-pressure, carbon-dioxide rich environment at temperatures between -120 C and + 45 C and can survive between -120 C and + 110 C. 9,10 The Rover’s suspension for wheels uses a rocker-bogie mobility system. This system doesn’t use springs. But, it rotates the joints to rock the Rover’s body up and down depending on the positions of the wheels to keep the Rover balanced on a rough surface.11 The wheel diameter is 0.25 m and the ground clearance is 0.30 m so that it can easily overcome rocks taller than its wheel diameter. Also, for the mobility system to live longer, we reduce the total mass of the wheels and differentials.12 Our electronic components must survive at night temperatures on Mars, which can drop to -96 C. Also, these electronic components must operate in the hazardous environment by cosmic radiation and electromagnetic emissions. So, we use only electronic components radiation-hardened and protected against cosmic radiation by placing them inside Rover’s core

AAE 450 Senior Spacecraft Design Spring 2004 4 Chapter Number and Title body, the Warm Electronics Box (WEB). The WEB mainly consists of a 5056 Aluminum honeycomb composite but also contains Silica Aerogel, lowest density material of any known solid nicknamed “Blue Smoke”. Aerogel provides the inside of the WEB with thermal isolation 39 times more insulating than the best fiberglass insulation. The gold coating inside and nickel coating outside the WEB give additional thermal isolation to the Rover’s body. The nickel coating also acts as EMI shielding to protect the interior electronic components against electromagnetic wave emissions. In addition, Thermostats and Heat Switches controls the Radioisotope Power System to keep the inside temperature of the WEB between -40C and +40C. This thermal control system uses the heat, whish is supposed to convert to electrical power to heat up the inside of WEB, while it uses the waste heat by the power conversion to cool it down. 11, 13, 14, 15, 16

Figure 2. Radioisotope Thermoelectric Generation 15

Our Rover has its brain inside not the head but the body. The computer in the Rover runs with a 64-bit RAD750, radiation-hardened version of the PowerPCTM750.17 It also runs the VxWorks. The Operating System, also running on the MER, has an excellent track record of reliability on the previous space missions. It also allows the astronauts to add a software patch without interrupting the mission. So, whenever the astronauts find a problem with the Rover’s software, they can fix it uploading a new code while keeping the rover operating. 18 The Rover has another important device in the WEB, an Inertial Measurement Unit (IMU). The IMU provides tri-axial information on its position, allowing the Rover to make precise vertical, horizontal and rotating movements. This Rover uses the same IMU to tell an F- 16 pilot which way is up and down to just drive on the ground, because it is quite a challenging to keep a good idea of its position and which way it is heading on the rough Martian Surface. 19 The rover carries two types of Science Instruments on its neck and three at the end of its left arm.

The instruments on the neck help the astronauts to select, from a distance, which rocks and soil to investigate in detail. A pair of high-resolution stereoscopic color visible to near-infrared Panorama Cameras (Pancams) image rocks and soils. A thermal infrared Mini-Thermal Emission Spectrometer (Mini-TES) catches a signal from the suite of minerals from far away. The instruments at the end of the right arm conducts close up studies of the targeting rocks and soils. A Microscopic Imager (MI) generates extreme close-up images of rocks and soils. Along with other instruments, the MI provides their mineral and element compositions. An Alpha-Particle X-ray Spectrometer (APXS) studies the alpha particles and X-rays emitted from rocks and soils to determine their elemental chemistry. A Ramon Spectrometer provides close-up "finger-print" analysis of rocks and soils to characterize their minerals and determine the chemical features. It doesn’t require any sample preparation, and also can detect organics like a bone.

1.2 Rover Capabilities - Masaaki Atsuta Rover Our Rover has a maximum speed of 5 cm/sec on a hard flat surface. Assuming it travels up a constant slope of 10º , which is a high estimate but doesn ’ t significantly affect results, we estimate that our R over can traverse Mars at an average speed of 3 cm/sec . The Radioisotope Power System produces 4800 watt-hours of energy per Martian day. This energy is about five times more than the energy that the Solar Power System of the Mars Exploration Rover can produce (900 watt-hours per Martian day). 8,9 The power production of the radioisotope power is independent of not only the accumulation of dust, but also the day/night cycle and the distance from the Sun. 7 Our Rover also has an ultimate hazard avoidance system, the astronauts on the spaceship flying around Mars. Since they can control the Rover, their closeness makes hazard avoidance almost instant. Moreover, our Rover uses the brushless EC motors as its wheel actuators. Unlike the brushed DC motors, which the MER uses and which average service life lasts roughly between 1000 hours and 3000 hours, the brushless EC motors have almost everlasting life, only limited by bearing. Our Rover uses ball bearings to cause them less damage to the motors and so the mobility system should never break down. With these power, hazard avoidance system and wheel actuators, our Rover will be easily able to travel at close to the top speed and for more than1000 hours, even under unfavorable

AAE 450 Senior Spacecraft Design Spring 2004 6 Chapter Number and Title environment condition on Mars. So, We suggest that the Rover travel for a maximum 2.5 hours/day and the Rover can reach a total distance about 180 km. 12 This figure of the total roving range might sound far beyond reality. For instance, the goal for the 92-day MER Mission is only 1 km and even the goal for the 687-day is 6 km to 9 km (initially 30 km). But, in light of our rover’s unparalleled capabilities, the number is feasible enough. Thus, our Rover can aggressively explore Mars and collect interesting samples for return to Earth. APPENDIX A - GENERAL BASELINE ROVER SPECIFICATIONS Mass: approximately 155 kg

Wheelbase (front to rear): 1.2 m Wheel Size: ~ 0.25 m diameter, 0.15 m width Track Width: 1.1 m (outside of wheel to outside of wheel) Maximum Obstacle Height: 0.30 m rock Top Deck Height: approx 0.6 m above ground Rover Body Dimensions: approximately 0.6 x 1.0 x 0.3 m Mast Instrument Platform Height: 1.0 m above ground Arms : 6 degree of freedom (DOF) One Sol Range: Terrain dependent (50 m Nominal) Guidance, Navigation & Control Sensors: Cameras, LN-200 Effective Stereo Range (Navcams) ~50 m RPS Power: 200 W continuous (2 RPSs) Thermal Control: Heat from RPS: Cool from waste from RPS Landed Operational Lifetime: 365 Earth Days

10-a Reid, Lisa K, Braun, and David F., Noon, “Robotic Arm and Rover Actuator Systems for Mars Exploration”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 1999 10-b The Mars Technology Program (MTP), “Mars Technology Program”

12 Krishnan, Satish, and Voorhees, “The Use of Harmonic Drives on NASA’s Mars Exploration Rover”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, Drive International Symposium 2001 , November 19-21, 2001 13 “Mars Exploration Rover Mission”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA http://www. marsrovers.jpl.nasa.gov/home/index.html 14 Savage, Donald, Webster, Guy and Brand, David “Mars Exploration Rover Landings Press Kit January 2004” NASA, Hanover, MD, Kit January 2004

S. W. Squyres et al, “The Athena Mars Rover Science Payload,” 29th Lunar and Planetary Science Conference, Abstract #1101, Lunar and Planetary Institute, Houston, 1998

Wang A., Haskin L. A., Lane, A. L., Wdowiak, T. J., Squyres S. W., Robert, J. Wilson, Larry E. Hovland, Ken S. Manatt, Nasrat Raouf, and Christopher D. Smith “Development of the Mars Microbeam Raman Spectrometer (MMRS)”, Journal of geophysical research. Res. 108, NO. E1, 5005,doi:10.1029/2002JE001902, 2003.

Wang, Alian; Haskin, Larry A.; Lane, Arthur L.; Wdowiak, Thomas J.; Squyres, Steven W.; Wilson, Robert J.; Hovland, Larry E.; Manatt, Ken S.; Raouf, Nasrat; Smith, Christopher D. Development of the Mars Microbeam Raman Spectrometer (MMRS). Journal of Geophysical Research, [Planets] (2003), 108(E1), 5/1-5/18. CODEN: JGPLEH ISSN:0148-0227. CAN 139:75764 AN 2003:313472 http://merpip.jpl.nasa.gov/MER-PIP.pdf

AAE 450 Senior Spacecraft Design Spring 2004 8 1 Rummel , John D., Race, Margaret S. DeVincenzi, Donald L., Schad, P. Jackson., Stabekis, Pericles D., Viso, Michel., and Acevedo, Sara E., “A Draft Test Protocol For Detecting Possible Biohazards in Martian Samples Retuned to Earth”, NASA, Hanover, MD, October 2002, NASA/CP-2002-211842 2 Mahaffy, Paul R. and 15 co-authors (2003), The Organic Contamination Science Steering Group, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 12/02/03 3 Tyvek®”, DuPont, Wilmington, DE, http://www.tyvec.com 4 “Planova ® filters are designed for virus removal”, Asahi Kasei America Planova Division, Buffalo Grove, IL, http://www.asahi-kasei.co.jp/planova/en/product/filters.html 5 “Preliminary Report: A Study of Options For Future Exploration of Mars”, Mars Science Program Synthesis Group, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 04/18/03 6 Cataldo, Robert L. “Power System Evolution: Mars Robotic Outposts to Human Exploration”, Power System, NASA Glenn Research Center, Cleveland, OH, AIAA Paper 2001-4592 7 Arvidson, Raymond “NASA Mars Exploration Program: Mars 2007 Smart Lander Mission”, Science Definition Team, NASA, Hanover, MD, 10/11/01 8 Heninger, R., Sandler, M., Simmons, j. , Muirhead, B., Palluconi, F., and Whetsel, C., “Mars Program: Mars Science Laboratory Mission 2009, Landed Science Payload DRAFT Proposal Information Package”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 11/21/03, D-27202 9 Maxon Precision Mortor“Maxon EC Motor”, Burlingame, CA http://www.maxonmotorusa.com/ 10 Scott, Dr. Stanley, Director, Advanced Programs, Alliance Spacesystem Inc, Pasadena, CA, “Email to the author”, 02/12/04 11Viotti, Michelle, “Mars Exploration Rover Mission”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA http://www. marsrovers.jpl.nasa.gov 12 Mars Technology Program, “Mars Technology Program”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 13 Lee, Darlene S., “Design and Verification of the MER Primary Payload Mars Exploration Rover Primary Payload Design and Verification”, Spacecraft & Launch Vehicle Dynamics Environment Workshop Program, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 06/17/03 http:// www.aero.org/conferences/sc-lv/pdfs/lee_mer_03.pdf 14 “Aerogel” , NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, http://stardust.jpl.nasa.gov 15 Schmidt , George, Wiley, Robert, and Furlong, Richard, “Radioisotope Power Systems (RPS) for New Frontiers Applications”, New Frontiers Program Pre-proposal Conference, Washington, DC, 11/13/03

16 Hickcy, Gregory S., Sword, Lee and Schcnker, Paul “Structural Design Challenges for Mars Rovers”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 1997 17 “RED750TM”, BAE SYSTEMS, Filton, United Kingdom, http://www.red750.com 18 “VxWorks® 6.0”, Wind River, Alameda, CA, http://www.windriver.com 19 Neil ,Dan, “Kicking the Tires on Mars: An auto reviewer finds rover Spirit a bit pricey -- $410 million, with destination and delivery charges -- but enthuses it really shines off-road”, the Los Angeles Times, Los Angles, CA, 01/19/04 Mars Exploration Rover Mission Participating Scientist Program, “NASA Announcement of Opportunity Proposal Information Package”, NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA

Squyres, S., etl, “Mission to Mars”, Cornell University, Itaca, NY, 2001 Haskin, Larry, Wang, Alan, Jolliff, Bradley, and Kuebler, Karla, “Why send the Athena Ramon spectrometer to Mars?”, Department of Earth and Planetary Science and McDonnel Center for the Space Science, Washington University, St. Louis

Kuebler, Ms. Karla, “Email to the author”, 02/12/04