Revision C June 5, Author: Ryan Connolly

Transcription

1 The P-POD Payload Planner s Guide Revision C June 5, 2000 Author: Ryan Connolly

2 P-POD Payload Planner s Guide: Revision B 5/15/00 2 of INTRODUCTION The Space Development, Manufacturing & Integration (SDMI) Team is positioning Cal Poly, San Luis Obispo to be at the center of small satellite development. Working with Stanford s Space Systems Development Laboratory (SSDL), the goal is to produce a standardized platform for small orbital experiments. Known as CubeSats, these tiny space vehicles are classified as PicoSatellites, meaning that the entire satellite weighs less then one kilogram. The 10-centimeter cubes are designed to house small experiments that otherwise would be cost-prohibitive to flight validate. Universities, alongside industrial and governmental interests, will be able to place their own CubeSats into orbit using our standardized deployment system. Cal Poly s own satellite, PolySat, will be one of the first of these new CubeSats. The SDMI is leading the way in the development of this deployment system known as the P-POD (Poly Picosatellite Orbital Deployer). The two versions of the deployer will mount to various launch vehicles, including the Delta II and the Minotaur. The maiden voyage for P-POD1 and P-POD2, along with PolySat is tentatively scheduled for Late Summer The total number of CubeSats launched is yet unknown, but the manifest could reach upwards of fifteen CubeSats on the maiden voyage. Cal Poly will oversee CubeSat development worldwide, and shall orchestrate all launching services with the launch providers. The integration design team is responsible for overseeing all incoming CubeSats, and verifying that they meet the design requirements set forth in the P-POD Payload Planner s Guide, which will be available to all interested parties. This ambitious interdisciplinary project, with students from all engineering majors and even several non-engineering majors, embodies the Cal Poly Learn by Doing credo in every respect. The purpose of the Payload Planner s Guide is to define clearly and carefully all CubeSat design requirements and all requirements for their interface with the deployer. This document is divided into the following sections: 1. Introduction 2. CubeSat Deployer Description 3. CubeSat Physical and Electrical Requirements 4. CubeSat Operational Requirements 5. Delivery Deadlines and Pricing Please refer to the SDMI website for more information regarding the project:

3 P-POD Payload Planner s Guide: Revision B 5/15/00 3 of PICOSATELLITE DEPLOYER DESCRIPTION This section of the document shall provide an overview of the CubeSat environment while onboard the deployer. The CubeSat provider shall be briefed on the following criteria required for integration into the deployer: 2.1 Deployer System Overview 2.2 CubeSat Containment and Deployer Interface 2.3 CubeSat Launch Environment 2.4 P-POD Orbital Environment Please refer to Section 3 for explicit CubeSat requirements. 2.1 Deployer System Overview The P-POD System has two distinct release platforms, each with a unique deployer that has different requirements on the CubeSats themselves Platform #1: P-POD1 With this configuration, the deployment system requires less design refinement for the CubeSats. The published specification tolerances for the CubeSat, as well as the outer mounting surface area provide for easier manufacturing of the CubeSats. The ultimate aim of this system is to provide deployment services to clients with limited manufacturing capabilities, such as universities and high schools, since the P-POD1 can accept a wider variation in CubeSat design. The mounting configuration for P-POD1 has three CubeSats per POD, with each CubeSat located by their corners via a series of mounting blocks. The three CubeSats sit next to one another on a base that slides vertically on roller slides, and two doors, which remain closed and locked until deployment, confine the entire base. Two Compression Springs provide the launching force, and the doors are opened via a cam system that ensures that the doors are fully opened when the base reaches its maximum height. Figure 2.1. P-POD1 Concept Model. (Left: Doors Open Right: Doors Closed) Note: As of the publishing date of this document, the P-POD1 is still under design review. Anticipated release of all design documentation is Winter No further mention of the P-POD1 design shall take place in this edition of the Payload Planner s Guide.

4 P-POD Payload Planner s Guide: Revision B 5/15/00 4 of Platform #2: P-POD2 This configuration of the deployment system, which is in the final design phase, represents the method of deployment for all customers. CubeSats aimed for deployment in P-POD2 must meet tighter tolerances and stricter design requirements, therefore limiting clients to those with highly accurate manufacturing capabilities. The deployment device consists of a series of machined aluminum tubes, with each tube composing one unit, or pod. Each pod is modular and can be assembled in a variety of configurations with other pods to accommodate many launch vehicle requirements. A single spring handles the deployment force, and a hinged spring-loaded door at one end of the tube restrains the CubeSats. A non-explosive actuator releases the door. Three CubeSats shall be positioned in each P-POD2 unit, with a 6.5 mm clearance distance from all six sides of the CubeSats. This clearance distance allows for mounting of any external features (solar panels, antennas, etc.) that extend above the CubeSat surface. Four 7mm standoffs shall be included (on two opposing sides) in the structure of each CubeSat in order to achieve proper spacing between each satellite within the launch tube. Detailed drawings of the deployer and CubeSat form factors can be found in Appendix A. Figure 2.2. Artist s conception of P-POD2 Deployment Device

5 P-POD Payload Planner s Guide: Revision B 5/15/00 5 of CubeSat Containment and Deployer Interface The CubeSats, when loading within the deployer, shall be constrained by the rail system of the tube, as well as secondary loading washers pressing them against the secured door. The rail design prevents jamming of the CubeSats during deployment, but requires tight tolerances on the outside dimensions of the CubeSats. The designated rail contact surfaces on each CubeSat must have a smooth surface finish, as detailed in the CubeSat requirements drawings in Appendix A. When loaded into the deployer, all CubeSat power must be completely off, and the CubeSats may only be powered on once clear of the tube. To accomplish this, killswitches (microswitches) must be mounted to the exterior of each CubeSat (in designated areas stipulated on the requirements drawings) to turn off all power when compressed. Also, the microswitches must be flush with the CubeSat surface when compressed. In addition to the kill-switches, a remove before flight pin must be furnished in the location stipulated on the CubeSat requirements drawings. This provides a universal method to ensure all CubeSats remain dormant during loading into the deployer. Additionally, an optional USB data port may be provided on the CubeSats in the location shown on the specification drawings. Access to the port will be provided on the deployer tube, such that final access to the CubeSat is available after integration to the deployer CubeSat Launch Environment The CubeSats shall be launched with an exit velocity between 0.5 and 1 foot per second. The CubeSats shall have a small relative velocity and will remain close to one another for a relatively long time. No intentional spin is imparted to the CubeSat during launch P-POD Orbital Environment The P-POD2 system may be launched aboard the OSP Space Launch Vehicle, and hardmounted to the JAWSAT satellite as its primary payload. The details of the orbit and launch altitude are not yet known. Additional launch possibilities may arise, and any changes shall be published immediately. The launch vector of the CubeSats with respect to Earth and launch vehicle will be unknown at the time of deployment, and all clients must accept this factor at time of CubeSat installation into the Deployer. P-POD2 shall experience the space vacuum and radiation dosage of a typical low-earth orbit environment. Predicted temperatures range from -40 C to 80 C, and large temperature fluctuations are possible. There will be no thermal control within P-POD2, so all CubeSats must be able to withstand these environmental fluctuations.

6 P-POD Payload Planner s Guide: Revision B 5/15/00 6 of CUBESAT PHYSICAL AND ELECTRICAL REQUIREMENTS This section of the document shall provide the physical (overall shape, size, weight) and electrical requirements for the CubeSats traveling aboard the P-POD2 system. The supplier testing criteria for the CubeSats is also outlined in this section, and should be used by CubeSat designers to design, construct, and test the satellites before delivery to Cal Poly. Any CubeSat that meets all of the requirements and passes all of the required tests shall be considered flight worthy by the P-POD team. Note: Once the design of P-POD1 is complete, requirements shall also be set forth for flight aboard that system as well Dimensions The CubeSat shall conform to the shape and size specified in the CubeSat specification drawings in Appendix A Mass Properties The CubeSat shall have a maximum mass of one kilogram. A requirement for the location of the center of mass for each CubeSat has not been established, but design teams should consult with Cal Poly before finalizing any design Materials All CubeSats must be constructed of, and contain, only NASA space qualified materials. Please refer to the Cal Poly Integration Team for questions concerning materials. No explosive devices or materials shall be used unless explicitly approved by the P-POD team. All surfaces that are designated on the CubeSat requirements specifications as rail interfacing shall be constructed to minimize friction at the rail/cubesat interface. All CubeSat shells shall be constructed of 7075 Aluminum to avoid any thermal mismatch between the deployer and CubeSat Electrical Requirements The CubeSats shall have no external electrical wire connections to the P-POD system Testing Requirements A modified, single CubeSat version of the deployer will be provided to each CubeSat design team to allow full environmental testing of the CubeSats. This Test-Tube will have mounting brackets for a 3-axis shake table test, and also will serve as the shipping container for the CubeSat.

7 P-POD Payload Planner s Guide: Revision B 5/15/00 7 of Vibration Tests The CubeSats shall successfully complete an independent vibration test simulating the expected launch load conditions Thermal Vacuum Tests The CubeSats shall successfully complete an independent thermal vacuum test simulating in-orbit conditions Electromagnetic Interference Testing The CubeSats shall successfully complete an independent electromagnetic interference test Integration Tests The CubeSats shall successfully complete a vibration test after integration with the P- POD2 system. The CubeSats shall successfully complete a thermal vacuum test after integration with the P-POD2 system. The CubeSats shall successfully complete a electromagnetic interference test after integration with the P-POD2 system. NOTE: The P-POD team must approve all independent testing and proof of results must be provided at time of delivery Adverse Affects of P-POD Thermal Affects The CubeSat operations shall not thermally affect P-POD2 in any adverse manner Electrical Affects The CubeSat operations shall not interfere with operations of the P-POD2 electrical system in any way Radio Frequency (RF) Effects The CubeSat operations may not interfere with the P-POD2 communication system in any way.

8 P-POD Payload Planner s Guide: Revision B 5/15/00 8 of Physical Effects The CubeSat operations cannot interfere with the normal operations of the P-POD2 structure or components. 4. CUBESAT OPERATIONAL REQUIREMENTS This section of the document outlines the operational requirements for each CubeSat. These requirements are necessary in order to ensure that no one CubeSat is a threat to any other within the same launch tube, or a threat to the mission as a whole. Because CubeSat deployment is the sole mission of P-POD, the highest level of importance is given to the CubeSat missions themselves. In this section, operational requirements are divided into three areas: 4.1. Pre-deployment operations: This sections covers preflight planning and testing to ensure that all CubeSats are flight-worthy and ready for integration into the deployer Deployment operations: The focus in this section is on the state in which the CubeSats must operate when contained within the deployer, and the methods allowed to activate the CubeSats upon deployment from P-POD Post-deployment operations: this section covers methods of communication between the CubeSat and ground station Pre-Deployment Requirements Testing Plans Each CubeSat design team must submit a plan and detailed procedure for the following validation tests: Vibration, Thermal-Vacuum, Electromagnetic Interference, and Integration. All test plans must be in accordance with the requirements set forth in Section 3 of this document. All results must be submitted to the P-POD team for review, and should be contained in a formal report. The CubeSat design teams shall perform all tests independently, and a member of the P- POD team will be available to aid of consult during each procedure. For the integration test, a joint team shall ensure proper interface between CubeSat and the deployer. In addition to pre-flight testing, each CubeSat team must provide a detailed list for preand post-launch checkout. This plan must indicate that the CubeSat is ready for the mission, and all internal systems are operating nominally. Once the CubeSat is deployed, the post-launch procedures shall be carried out to confirm that the CubeSat is able to begin its mission.

9 P-POD Payload Planner s Guide: Revision B 5/15/00 9 of Operations Guide The CubeSat design team must submit a formal operations guide to the P-POD team in order to outline the primary mission and identify the functions of the CubeSat s payload. This guide should also document the CubeSat s compliance with all of the requirements set forth in this document. Expected behavior of the CubeSat during the entire mission (Pre-deployment, deployment, post-deployment) shall also be documented within this guide. Uplink and downlink frequencies shall also be clearly documented to avoid communications error with the other CubeSats on the mission. All communications with the CubeSats are left to the CubeSat design teams. P-POD shall not provide any communication with any of the CubeSats prior, during, or after they are deployed. However, the deployer will relay launch information back to the ground station, which will verify if the CubeSats were properly deployed from the system Physical Constraints This section of the document outlines the method in which all CubeSats are loaded into the deployer to achieve proper dormancy in each satellite. A detailed procedure must be submitted to the P-POD design team, prior to launch, that will explain the proper loading procedure for each CubeSat in order to ensure that all power is turned off when loaded into the deployer. As stated in Section 3, all CubeSat operations (electromagnetic, electrical, etc.) must be suspended until the CubeSat is clear of the launch tube during deployment Deployment Requirements Because no single CubeSat s mission is seen as more important than any other during the mission, no CubeSat design team shall be given the choice of deployment times or vectors. All CubeSat design teams must agree that their mission may begin at any time, and should be ready to begin their mission within the defined launch window. Because each P-POD tube will contain up to three CubeSats, the CubeSat design teams must coordinate with one another concerning which tubes they will mount into. The P-POD design team will assign tubes and have the ultimate decision if any conflicts arise. CubeSats may only begin their missions upon exiting the deployment tube. No CubeSat may self-actuate until clear of the deployer. Also, no exterior components of the CubeSats, such as antennas or other devices, are allowed to contact the deployment tube. See CubeSat Specifications, Appendix A for details Post Deployment Requirements Once free of the deployer, the CubeSat should activate and begin communication with its ground station. At this time no ground station has been established for CubeSat communication, and we will supply all interested parties this information as soon as it becomes available.

10 P-POD Payload Planner s Guide: Revision B 5/15/00 10 of 19 Once the CubeSat s mission ends, it must not pose a threat to any other orbiting spacecraft. There must be proof that the CubeSat will de-orbit within a reasonable span of time after completing its mission. This proof should be given and documented in the CubeSat operations guide. 5. DELIVERY DEADLINES AND PRICING The current anticipated launch date for the P-POD2 maiden mission is Late Summer 2001, with a delivery date in Late Spring This requires constant and committed communication between the P-POD team and all CubeSat design teams. This final section of the document details the business-related aspects of the deployment system. Issues related to the following topics shall be covered: 5.1 P-POD Design Schedule 5.2 Design Reviews 5.3 Payload Planner s Guide Negotiations 5.4 Pricing 5.5 Contact Information 5.1. P-POD Design Schedule As stated above, the anticipated launch for P-POD and the CubeSats is August This launch opportunity is in the process of acquisition aboard the JAWSAT deployment vehicle on board the OSP Space Launch Vehicle. Table 5.1 outlines the major milestones and completion dates for the P-POD system. Milestone Completion Date Engineering Model Fabrication March 20, 2000 Flight Model Fabrication July 21, 2000 Environmental Testing of Flight Spacecraft September 1, 2000 Deployer Operational Verification October 1, 2000 Deployer Design Completion (Ready for Flight) December 1, 2000 Table 5.1. P-POD Completion Timeline

11 P-POD Payload Planner s Guide: Revision B 5/15/00 11 of 19 All CubeSats should follow the Timeline in Table 5.2: Milestone Completion Date Engineering Model Fabrication Summer, 2000 Flight Model Fabrication Mid-Fall, 2000 Environmental Testing of Flight Spacecraft Winter, 2001 Spacecraft Operational Verification Spring, 2001 CubeSat Delivery to Cal Poly Late Spring/Early Summer, 2001 Table 5.2. CubeSat Completion Timeline 5.2. Design Reviews The P-POD design team is currently scheduling weekly design reviews between the P- POD team and all CubeSat design teams. Once the CubeSat teams are identified, the P- POD team shall finalize the times for these reviews Payload Planner s Guide Negotiations The Payload Planner s Guide is a living document, and changes shall be made to this document as the P-POD design team sees fit. All CubeSat teams shall be given notice of the updates, and copies of the updated Guide provided immediately. If any CubeSat team feels that changes are required to this document, the P-POD design team shall put forth the highest degree of effort to see that those changes are made in a timely manner. If any problems should arise between the P-POD team and the CubeSat teams, Prof. Jordi Puig- Suari shall serve an arbitrator Pricing The P-POD Design team is providing launching and deployment services to all CubeSat teams. The price per CubeSat aboard the P-Pod system has not been determined. Please refer to the contact information at the end of this section for further details Contact Information The SDMI Student Project Leader is: Jeremy Schoos Voice: (805) jschoos@calpoly.edu

12 P-POD Payload Planner s Guide: Revision B 5/15/00 12 of 19 The Academic Advisor to the SDMI team is: Professor Jordi Puig-Suari Voice: (805) Fax: (805) jpuigsua@calpoly.edu Any questions related to this document or any other CubeSat questions should be directed towards the student project leader and carbon copied to Prof. Jordi Puig-Suari. Additional information concerning the P-POD system can be found at the following website:

13 P-POD Payload Planner s Guide: Revision B 5/15/00 13 of 19 Appendix A: CubeSat Design Requirements

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15 P-POD Payload Planner s Guide: Revision B 5/15/00 15 of 19 Appendix B: Deployer Overview

16 P-POD Payload Planner s Guide: Revision B 5/15/00 16 of 19 The Poly Picosatellite Orbital Deployer has been designed to provide a reliable and inexpensive solution to picosatellite deployment in space. It is the intent that universities and industry will be able to use the PPOD as a means of deploying standardized multifunctional satellites in space. The Cal Poly WESTEC team has developed picosatellite specifications for universities and industry wishing to use the PPOD to deploy space bound experiments. These specifications can been seen in DWG in Appendix B. An exploded view of the PPOD mechanical assembly is shown in DWG It uses a pin-puller actuator to release the spring-loaded door. A compression spring provides the initial force to deploy three CubeSats loaded in the PPOD. The picosatellites will be loaded into the device using the configuration shown in DWG Design Criteria The following criteria was used in the development of the PPOD: Temperature Extremes: -40 C to 65 C Maximum Force during Launch: 15g s Mass of the deployer must be equal to or less than 1.50 kg [3.3 lb] The satellites will weigh no more than 1kg The satellites will be 10cm X 10cm X 10cm Must ensure that the picosatellites will not tumble upon launch Must deploy the satellites at an exit velocity of no greater than 0.3 m/s [1 ft/s] (the slower the better but they must get out) Must provide a faraday cage to shield against any premature transmission from the picosatellites Must not be a threat to any other mission aboard the rocket Must be able to accommodate satellites with solar panels mounted on the external walls PPOD Design Results Material: 7075-T7351 AL Mass (empty): 1.67kg [3.7 lb] Fasteners: 6-32 machine screws and lock washers Spring Specs: Constant =.85 lb/in Free Length = 15 in. Solid Ht. = 1.5in

17 P-POD Payload Planner s Guide: Revision B 5/15/00 17 of 19 Part-by-Part Notes DOOR: DWG The door of the PPOD was designed to be as light as possible without sacrificing strength. The thickness of the door is in with portions trussed out to for weight reduction purposes. The pin-puller locates its pin through a 0.081in hole in one of the two flanges on the bottom of the door. When the pin on the actuator is triggered, the door will open as a result of the force applied by the torsion spring. It is intended that the force opening the door of the deployer will be strong enough to accelerate the door such that there will be no contact with the top picosatellite as it accelerates out of the deployer. This would prevent the satellite from tumbling upon deployment. The torsion spring and compression spring may need to be adjusted if future testing proves them ineffective in this respect. HINGE ROD: DWG The hinge rod is a 0.25in diameter steel rod. The door pivots about this rod. SIDE A: DWG There are two Side A parts to each PPOD deployer. The function of the Side A part is to act as a structural member of the assembly as well as a faraday cage. Side A has three in thick bars across the bottom, middle, and top of the part. These bars will eventually serve as mounting surfaces when the attachment configuration has been determined. The thicker material is needed in order to use countersunk fasteners for the final mounting configuration. The remaining material is in with portions trussed out to.030 in for weight reduction purposes. The rails are to provide a sliding surface for the picosatellites as they are being deployed. The rails will be treated with a Dicronite coating to reduce the coefficient of friction and to serve as a protective coating. By doing thermal expansion calculations for the given geometries, it was determined a in spacing could be left between the picosatellite side and each rail (see calculations in Appendix B). This would ensure that any expansion would not wedge the satellite inside the deployer. A +/-.005 in tolerance is also required for each picosatellite deployed using the PPOD. There are 12 holes in Side A for the 6-32 machine screws to pass through. These holes are not tapped. SIDE B: DWG There are 2 Side B parts to each PPOD deployer. The Side B parts are identical to the Side A parts except for their width and the location of the holes. The holes in Side B are drilled and tapped blind holes for the 6-32 machine screws. SLIDE: DWG

18 P-POD Payload Planner s Guide: Revision B 5/15/00 18 of 19 The slide is mounted on the compression spring and moves up and down throughout the assembly. The long legs serve to prevent any jamming against the rails within the launch tube. SPRING: DWG The spring has a free length of 15in and a solid height of 1.5in with a constant of 0.85 lb/in. It was designed based on providing a 3 kg mass an exit velocity of 1ft/s BASE: DWG The base is 0.25 inches thick and completes the enclosure of the PPOD. It has a circular pocket to locate the spring and to serve as weight reduction. The spring is attached to the base using a flat sheet metal part and small machine screws. There are four drilled and tapped blind holes that are used to fasten sides to the base. HINGE A & B: DWG & DWG The hinges A & B are mirror images of one another. They are used to locate the 0.25in rod, torsion spring, and the door to Side B.

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