SCOTTSBORO HIGH SCHOOL. Putting the Competition on Ice. I.C.E.M.A.N. Payload Status Document

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1 P.E.R.M.A.F.R.O.S.T. SCOTTSBORO HIGH SCHOOL Putting the Competition on Ice I.C.E.M.A.N. Payload Status Document

2 Payload Status Document 1.0 Introduction One of the many celestial bodies currently orbiting Saturn is Enceladus, an icy, geologically active, volcanic moon found in Saturn s outer E-Ring that is highly interesting to the space community. NASA s Science Definition Team wrote on Enceladus: a mission to Enceladus would produce compelling science that is highly relevant to NASA goals. For this reason, the University of Alabama Huntsville (UAH) based InSPIRESS outreach program has challenged high school students across Alabama to design a hypothetical payload to explore Enceladus. To meet this challenge, team PERMAFROST (Performing Enceludian Research while Making Academic Furtherances Regarding Our Scottsboro Engineering Team) has developed the orbital probe ICEMAN (Investigator of Cryogenic Enceludian Materials Around Saturn s Neighboring Space) for the purpose of confirming if Saturn s E- Ring is supplied by volcanic material emanating from Enceladus. PERMAFROST will accomplish this mission through comparative spectrometry of Saturn s E-Ring and of material orbiting Enceladus. 2.0 Science Objective The main science objective of Team PERMAFROST is to determine the relation of Saturn s E- ring to Enceladus, a moon of Saturn. The E-ring is believed to have been formed by ejections from cryogenic volcanoes located around deep crevices of Enceladus southern pole known as the Tiger Stripes. While Cassini, the NASA probe which first discovered Enceladus cryogenic ejections, performed supporting research for this theory, it was not Cassini s mission to determine the origins of the E-ring. Thus, Team PERMAFROST seeks to improve upon and confirm Cassini s research with more advanced instrumentation. In order to achieve this objective, Team PERMAFROST will collect material from Saturn s E- ring to compare its composition to material from Enceludian volcano ejections orbiting Enceladus. PERMAFROST s payload, ICEMAN, will eject spherical probes at Saturn s E-Ring and around Enceladus to passively collect dust samples there. If the composition of the E-ring material is comparable to the composition of Enceludian material, Team PERMAFROST can confirm the theory that the E-ring is formed by ejections from cryogenic volcanoes of Enceladus surface. Team PERMAFROST s second science objective is to discover whether or not Enceladus harbors life. Water is believed to lie at or near the surface of Enceladus, making it one of the best candidates for sustaining extraterrestrial life. If ICEMAN s laser spectrometry discovers either frozen water or carbon compounds in orbiting Enceludian material, these could be strong indicators of life on Enceladus. ICEMAN will also launch a probe at Rhea to determine the presence of rings around the moon, another controversy that PERMAFROST seeks to put to rest using laser spectrometry. Finally, ICEMAN will launch a probe at the F-ring for a comparative study between the F-ring and the E-ring. If this comparative study shows that the composition of the E-Ring and F-Ring are the same, it could be inferred that Enceladus supplies other rings of Saturn as well. 3.0 Instrumentation Table 1. Science Traceability Matrix Science Objective Measurement Objective Measurement Requirement Instrument Selected Determine if Enceladus supplies Saturn s E-ring by comparing Enceludian material to Saturn s E-ring Material. Determine whether or not Rhea has rings. Determine if Enceladus can harbor life. Composition of E-ring and Enceludian cryogenic ejections present in Enceladus orbit. Determine the presence of material orbiting in a ring around Rhea. Determine the presence of carbon compounds or frozen water in Enceludian material. Need to be able to analyze the compositions of collected materials. Need to be able to analyze the compositions of collected materials. Need to be able to detect carbon structures and frozen water in collected materials. Page - 2

3 Comparative study of the F-ring to E-ring. Composition of E-ring and F-ring material. Need to be able to analyze the compositions of collected materials. Payload Status Document Table 2. Instrument Requirements Instrument Mass (kg) Power (W) Volume (cm 3 ) Instruments Data Rate (bps) Accelerometer.0015 kg W cm 3 10mV/g 100Hz kg 0.15 W cm ms per spectrum Transmitter Micro Processor Data Volume (kbits) TBD Mounting/Structure Thermal Dimensions Stainless Steel flat surface TBD USB k to k 258k to 333k Support Equipment kg W cm bps TBD TBD TBD kg 1 W cm x 10 8 bps 2,228,072 kb Circuit Board 233K to 358K 7.11 H x 6.35 mm hex base (0.28 x 0.25" mm 32 x 12 x 3.8 mm 78 mm x 38 mm x 19 mm 4.0 Payload Design Requirements The Payload Design Requirements as outlined by InSPIRESS are as follows: First, the payload is required to leave the spaceship for data collection. Secondly, the payload needs to withstand the harsh environment of space while maintaining its ability to collect samples. Thirdly, the payload must not exceed a mass allowance of 5kg and its volume must not exceed 44x24x28 cm^3 (approximately the size of a paper box). Finally, the payload must not damage the UAH spacecraft upon launching. The table below illustrates how ICEMAN meets the Payload Design Requirements. Requirement Payload Design No more than 5 kg of mass Payload Mass: 4.98 Fit within 44 cm x 24 cm x 28 cm when stowed ICEMAN Volume: 20.8 cm x 20.8 x cm 20.3 cm Survive environment Aluminum Lithium shell to protect from particle impacts and erosion. Aero-gel insulation to survive freezing temperatures. No harm to the spacecraft Probes launched away from spacecraft. Minimalized muzzle pressure upon launching. Table 3. Payload Design Compliance 5.0 Alternative Concepts PERMAFROST considered two other concepts along with its final concept, ICEMAN. PERMAFROST s initial payload concept (Concept 1) collected material through retractable aerogel nets. Spectrophotometers with the output end on one side of the aero gel collector and the input end on the adjacent side would measure the composition of caught materials. This particular probe concept is similar to the NASA mission STARDUST, which used aero-gel nets to capture whole, unharmed samples of comet dust. Aero-gel was also favored by team PERMAFROST for its light weight and insulating abilities. After further review however, PERMAFROST decided that aero-gel nets, designed to capture whole samples to be returned to Earth, were unnecessary considering that the spacecraft will not be returning to Earth. Page - 3

4 A trashcan-shaped impacter (Concept 2) was also proposed; the impacter would be weighted at one end so that it would kick up dust off the surface of Enceladus. The falling debris would then be measured by spectrometers located at the bottom of the impacter. However, the trashcan impacter, considering the mass limit, could not be designed robust enough to survive impact. ICEMAN, a multiple spherical probes concept, was the third (Concept 3) and Final concept, and it is elaborated on in Section 7.0 Final Design ICEMAN. Payload Status Document 6.0 Decision Analysis Team PERMAFROST utilized a Payload Decision Analysis table to determine the integrity of each payload concept. Each concept was judged on a series of factors weighted by importance. The higher a concept scored the better it positively fulfilled a factor's definition. The payload concept with the highest overall score was considered the most viable option. Mass is defined as a concept's ease in meeting the mass requirements. Useful Mass is the amount of the mass allowance used by science-collecting instruments versus the amount of the mass allowance used by structural materials. Battery Requirement is an indicator of how much power a concept needs. Environment Dependent Survivability is defined as the harshness of the environment a payload concept is planned to perform its mission in; the higher the score, the lower the harshness of the environment. Deployment is the ease of successfully deploying a payload concept away from the UAH spacecraft. Targeting Requirements is defined by the chances of a payload concept, after being deployed, reaching its intended destination successfully. PERMAFROST made inferences based on a payload's design. Accuracy of Measurements indicates the payload concept's ability to accurately measure the material is collects. Science Achieved is the amount of side science each concept would achieve. Critical Measurement Probability is defined as the ability for a payload concept to achieve at least some amount of science should something go amiss. As evidenced by the table, Concept 3 is the most viable concept. Table 4. Payload Decision Analysis Figure of Merit Weight Factor Concept 1 Concept 2 Concept 3 Mass Useful Mass Battery Requirement Environment Dependent Survivability Deployment Targeting Requirements Accuracy of Measurements Science Achieved Critical Measurement Probability Total Final Design - ICEMAN The final design, formerly known as Concept 3 and now known as ICEMAN, is an array of spherical probes launched at predetermined locations. The design starts with a launching subsystem, which consists of four barrels. Within each barrel is a probe slightly larger than a softball. As the UAH spacecraft approaches designated launch locations, the individual probes will be shot out with a small amount of pressurized helium. Along each probe s surface are four cone shaped viewports with a thin aero gel cap and a cylindrical window of transparent aluminum oxide at the bottom. As a probe tumbles through space, dust and ice particles will penetrate the aero gel caps and become trapped within the cones. From there, the four laser spectrometers within the probe will determine the compositions of the dust and ice particles by measuring the emission spectra of elements of the particles. The position of each probe will be determined by the onboard accelerometer. The data collected by the laser spectrometers and Page - 4

5 Payload Status Document accelerometers will then be transmitted to the UAH spacecraft. Each probe has been designed with various materials to improve its chance of survival in Saturn s particulate rings, the harshness of open space, and against cryogenic volcano ejections. The physical design begins with a 0.635cm thick shell of aluminum lithium, a metal that was chosen for its impressive durability and low weight. This shell will protect the probes from bullet speed dust particles and the cryoprojections of Enceladus. Under that is a 1cm thick layer of cryogel, chosen for its high insulative properties. After the cryogel layer is the inner most part of the probe, lined by a cm thick casing of carbon fiber for structure, which houses the four laser spectrometers, the computer, and all other crucial electronics. 8.0 Design Analysis The primary value PERMAFROST had to find regarding the probe was its mass, which was determined by finding the sum of the masses of each individual layer, all recording instruments, specified battery masses, and the masses of Aluminum Oxide viewing ports and aero gel catchers. To determine the masses of each individual layer, PERMAFROST used the difference in the volume of two spheres: [ ] [ ( ) ] PERMAFROST then used the integral calculus method of volume by disks to determine how much volume to remove from each layer dependent on the volume of the viewing ports. Since the viewing ports are conical, these values changed based on which portion of the viewing port the layer crossed. This same method was also used to determine the volumes of aero gel and Aluminum Oxide viewing ports. Thus, PERMAFROST used the following equation: a = distance in cm from the center of the probe to the bottom of the layer b = distance in cm from the center of the probe to the top of the layer R is determined by the equation of the connecting line from the inner sphere to the outer shell expressed in terms of x Once Volumes were found for each material in the probe, PERMAFROST found their individual massed by multiplying their volumes by their densities, based on the equation below: Instrumentation masses were found online, and battery masses were calculated by first determining how much power each instrument would draw in watts, then determining how long these instruments needed to run in order to achieve their designated science objective. Finally, understanding that standardized space batteries run at 400, PERMAFROST divided their Watt Hours value to obtain the battery mass required to run a particular instrument for its designated period of time. The required battery masses of each instrument were then summed to determine the total battery requirement for each specific probe (since some probes, I.E. the E-Ring and F-Ring probes, did not need to survive as long as the Enceladus and Rhea Probes). Once PERMAFROST discovered a total mass, the probe was continually re-engineered the thicknesses of each layer until the mass requirements of the probe were fully met. Next, to determine each probe s required muzzle pressure upon ejection, team PERMAFROST utilized the technique of back-calculating from the desired altitude of orbit to the required muzzle pressure. This required that the team first find the orbits above both Enceladus and Rhea which would achieve the most accurate measurements by researching altitudes which Cassini measured from. Since the altitude of the orbit of a body is directly proportional to its velocity, the team could then back Page - 5

6 Payload Status Document calculate the probe s required velocity and thus the required muzzle pressure to achieve said velocity using the orbital velocity equation: V = G=universal gravitational constant M=mass of planet r=orbital radius Firstly, after researching that Cassini measured Enceladus from an altitude of 50 km, PERMAFROST concluded that an orbit of 50 km above Enceladus would achieve the most accurate measurements. Back calculating the required velocity by using the orbital velocity equation, PERMAFROST concluded a velocity of approximately 162 m/sec is required to obtain the altitude of 50 km, and that the required muzzle pressure for Enceladus to achieve the required velocity is psi. Unfortunately, PERMAFROST could not use the same method used to calculate the required muzzle pressure for Enceladus for Rhea. Utilizing the same formulas and back calculating method used for Enceladus, PERMAFROST found that to reach a velocity of m/sec at an altitude of km above Rhea, the required muzzle pressure would be psi. This muzzle pressure would exert a force of 8000 G on the probe, triggering a critical failure. PERMAFROST concluded that the next best alternative would be to bisect Rhea s inferred rings twice; though the bisecting method provides the probe less time around Rhea, it still provides the probe enough opportunity to confirm the presence of Rhea s inferred rings. When the UAH spacecraft is at an orbital radius of 1615 km, ICEMAN will launch a probe forward at a velocity 5% faster than the velocity of the spacecraft. Thus, PERMAFROST concluded the probe must achieve a velocity of m/sec and a muzzle pressure of psi to achieve that velocity. Finally, as the UAH spacecraft will be traveling between the E-ring and the F-ring, ICEMAN will simply launch probes perpendicular to the UAH spacecraft in order reach the E-ring and the F-ring. Table 5. Final Design Mass Table Function Deploy 1.22 Measure 0.41 Collect Data 0.08 Provide Power 0.65 Send Data 0.01 House/Contain Payload 2.54 Total Payload Mass 4.98 Mass (kg) Figure 3. Payload Final Design cm Al 2O 3 Viewing Port Page - 6