August 20, EPICS Design 1 Teams Design EPICS Program Colorado School of Mines th Street Golden, CO Dear EPICS 1 Teams,

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1 Joel G. Duncan, Ph.D. Teaching Professor Design EPICS Program GOLDEN, CO USA August 20, 2013 EPICS Design 1 Teams Design EPICS Program Colorado School of Mines th Street Golden, CO Dear EPICS 1 Teams, The purpose of this letter is to invite you to participate in a program funded by NASA as part of its National Space Grant program. This invitation focuses on a specific design challenge the Colorado Space Grant Consortium offers through its DEMOSAT balloon flight program, which gives students at institutions around the state an opportunity to design, fabricate, launch, recover, and analyze data from payloads ranging from atmospheric characterization to bacteria experiments and technology demonstrations. The DEMOSAT design project I am requesting of you contributes to NASA s efforts to identify and track Near Earth Objects (NEOs), which are asteroids or dead comets that cross the Earth s orbit and have the potential to cause serious damage to civilization if they collide with Earth. Once NEOs are discovered, collection of accurate orbital data can allow scientists to determine whether impact will or will not occur and to formulate and implement mitigation plans as necessary. NEO orbital data obtained through currently used Earth-based optical methods is not accurate enough to predict whether the object poses a real impact threat to Earth. One way to obtain more precise orbital data is to launch an NEO Transponder Probe (NTP) to deploy one or more Deep Space Network transponders/beacons, with appropriate instrumentation, to the surface of the NEO to provide long-term, accurate tracking of the NEO s location relative to Earth. The DEMOSAT balloon flight program offers a platform to simulate deployment and landing of an NTP and test the overall robustness of the NTP design. To meet this design challenge, I request that you design and build a working prototype of the housing that will protect the instrumentation during a free-fall landing, with a landing gear that will right the NTP to vertical upon landing, readying it for proper positioning of antennas for operation. The winning design will be awarded CSM s spot on the balloon flight later this year. DEMOSAT Demonstration Parameters The NTP housing and landing gear design must function within the constraints of the DEMOSAT balloon flight configuration, which consists of seven satellites (including the winning design submitted by CSM) tethered to a balloon. The balloon and satellites are launched from a site east of Denver. The balloon ascends to approximately 100,000 feet where it

2 bursts. The tethered satellites then descend on a parachute and impact the ground at approximately 35 mph. Housing and Landing Gear Design Considerations For purposes of the demonstration, the landing gear must be able to bring the satellite to rest topside up independent of its orientation upon landing, where top is a previously determined plane of the housing. Please give special consideration to the balloon tether in the landing gear design and operation. Design Guidelines and Criteria Maximum weight of the satellite/ntp must not exceed 1.5 kg, including the weight of the housing, the landing gear, and a dummy transponder. Preferably, the design will allow for the tether to pass through the center of the satellite. Assume zero-g conditions on the surface of the NEO in your design solution. Tests must be conducted to demonstrate the satellite s survivability of an impact velocity of 35 mph upon landing. Cost of the working prototype is not to exceed $100. For specific requirements of the DEMOSAT program, please see the DEMOSAT User s Guide at: An attachment to this letter provides more in-depth technical background information on the nature and tracking of NEOs. I look forward to your contributions to solving this important technical challenge. Please feel free to contact me with any further questions you may have regarding this request. Sincerely, Joel G. Duncan, Ph.D. CSM Affiliate Director, Colorado Space Grant Consortium Attachment: Background Technical Information

3 Background Technical Information for the Near Earth Object Transponder Design Project What are Near Earth Objects? Thousands of asteroids and dead comets ranging in size from a few meters to several kilometers in diameter have orbits that cross that of the Earth. Collisions of these space rocks, or Near Earth Objects (NEOs) as they are known, with the Earth are inevitable and can pose a serious threat to humanity at municipal to global catastrophic scales. NEOs have collided with Earth many times throughout its 4.5 billion year history, releasing tremendous energy and creating scars in the Earth s surface that are preserved in the form of impact craters. Attesting to past Earth-NEO collisions, some 175 impact craters ranging in diameter from a kilometer or so to greater than 300 km, have been discovered on Earth. Hazards Associated with NEO/Earth Collisions Sixty-six million years ago the Earth collided with a 10 km diameter asteroid. The impact excavated the 180 km diameter Chicxulub Crater in the ocean floor just north of what is today the Yucatan Peninsula of Mexico. The tremendous energy released by this impact devastated the Earth s global ecosystem and modified the climate. Most scientists believe that this impact caused a mass extinction of 75 percent of life on Earth, including the dinosaurs. Even the impacts of relatively small asteroids only 30 m to 40 m in diameter have the potential to inflict substantial damage if they strike a metropolitan area. Fifty thousand years ago a 30 m diameter iron asteroid blasted into then forested landscape of central Arizona that was teaming with mammoths, bison, and camels. The impact released the energy equivalent to a small nuclear explosion, carving out a crater 190 m deep and 1.4 km across, which we know today as Barringer or Meteor Crater. The blast accelerated branches, rocks, and other debris, causing shrapnel-type wounds in animal life as far away as 10 km to 13 km from ground zero, as shown in Figure 1. A fireball generated by the impact exposed vegetation and animals to tremendous heat, causing burn damage out to a range of approximately 10 km. The impact likely killed animals within 3 km to 4 km of the impact site, and maimed those as far away as 16 km to 24 km. Scientists predict that impacts the magnitude of Meteor Crater will occur every 6000 years and are thus relatively frequent events over the scale of geologic time.

4 Figure 1: Damage zones associated with the Meteor Crater Impact A similar impact today could destroy a city and kill many people. Greater, more widespread damage would result from an impact in the ocean, where resulting tsunami waves could devastate coastal cities over large areas of the Earth. Because oceans cover roughly 70 percent of the Earth s surface, impacts are more likely in oceans than on land. Tracking Hazardous NEOs To reduce the threat and potential destructiveness of Earth-NEO collisions, NASA and space agencies around the world have implemented programs to identify and track NEOs. Once an NEO is discovered, these programs use optical and radar methods to determine its orbit and predict if it poses an impact threat. These methods may be sufficient for predicting the threat posed by larger NEOs, but for those with diameters less one km orbits calculated using these methods have limited accuracy and may suggest that hazard to Earth exists, whereas more accurate data may indicate otherwise. More precise orbital determinations for these smaller NEOs helps focus impact mitigation planning only on the hazardous NEOs.

5 Using NEO Transponder Probes (NTPs) for More Accurate Tracking One method for obtaining accurate orbital data is to launch an NEO Transponder Probe carrier spacecraft that would deploy one or more Deep-Space Network transponders/beacons (NTPs), each containing a radioisotope power supply and equipped with appropriate antennas, to the surface of the NEO. Presence of these NTPs would allow long term, accurate tracking of the NEO s location relative to Earth. After rendezvous with the target NEO, the NTP carrier spacecraft orbits the NEO for about 3 months, using remote sensing to select the optimum NTP placement site location. After site selection, the spacecraft s orbit altitude decreases to anywhere from 100 m to 1 km while maintaining the placement site in the NEO orbit plane. As the spacecraft approaches a point directly above the placement site, it fires thrusters to kill its orbit velocity and begin a free-fall to the NEO surface. At that point, the NTP separates from the spacecraft and descends in an uncontrolled free-fall to the NEO surface as the carrier craft returns to orbit. Because the descent is uncontrolled, a special landing gear system is deployed to right the NTP to vertical so antennas can be deployed properly for operation..