CubeSat Deorbit Devices
Midterm Report
Old Dominion University
Project Design & Management II
March 15, 2011
Dr. Robert Ash
Lindsey Andrews
Jake Tynis
Joshua Laub
Abstract:
The integration of electronic devices and subsystems within a satellite bus is not a trivial issue in the design of a spacecraft. The benefit of this research is immediately apparent, expanding experiment opportunities using low-cost access to space utilizing the CubeSat platform. However, once orbit has been achieved, a CubeSat's lifetime is finite and can be on the order of decades. This research has shown that an effective deorbit device can be deployed to shorten the lifetime of a CubeSat. This technology is becoming more valuable as the total number of CubeSats in orbit increases. The future safety of the earth orbit environment with regards to orbital debris depends on the ability to safely deorbit nanosatellites.
Table of Contents
Introduction 5
I. Literature Review 5
II. Rationale 7
III. Project Objective 8
IV. Benefits 9
Proposed Approach 9
Finalized Approach 11
I.Materials 11
Organization 20
Cost Consideration 21
Summary 23
Appendix 24
I. Works Cited 24
II. Secondary Material 25
List of Figures
Introduction I. Literature Review
Low cost access to space has been an area of concern since the early days of spaceflight. Over the decades, advances in technology have allowed space structures and avionics to decrease in size. The CubeSat architecture takes advantage of both of these advances.
The CubeSat design standard is a collaborative project between California Polytechnic and State University and Stanford University. A standard CubeSat is a 10 centimeter cube with a total mass of less than 1 kilogram. The premise behind CubeSat is to be a secondary payload to a host launch system. In other words, if there is an extra mass allotment on a launch, CubeSats have the opportunity to be deployed. CubeSats are deployed using the Poly-Picosatellite Orbital Deployer, P-POD, as seen in (California Polytechnic)Figure : Six CubeSats and their respective P-POD launcher (California Polytechnic), also developed by California Polytechnic and State University (California Polytechnic).
Figure : Six CubeSats and their respective P-POD launcher (California Polytechnic)
As stated previously, the standard size for a CubeSat is a 10 cm cube (referred to as 1U). This can actually be increased to a maximum size of 10 cm by 10 cm by 30 cm and 3 kilograms (3U). Obviously this is a larger, more expensive endeavor than a standard 1U CubeSat; however it is a possibility.
The design challenges of CubeSats are very apparent: small size. The small size and mass requirements seriously constrict the payload. The only volume and mass remaining for the experiment is after essential systems have been integrated in the bus. There must be an electrical power system, telemetry, data handling, thermal control, and various other systems that must be incorporated prior to the experiment.
There are certain companies who specialize in commercial off the shelf (COTS) CubeSat subassemblies, as seen in (Pumpkin, Inc.)Figure : COTS CubeSat Structure (Pumpkin, Inc.). These kits greatly aide in the development time and budgeting of a spacecraft. The main idea behind CubeSats is to keep cost and development time to a minimum.
Figure : COTS CubeSat Structure (Pumpkin, Inc.)
The launching of artificial satellites into earth orbit has produced some unintended side effects. Every satellite which is put into orbit has a finite useful lifetime; at some point they will no longer function and then become debris. As the total number of orbiting satellites and debris increase, attention must be focused on minimizing their orbital lifetime. There are currently over two million kilograms of space debris in orbit around the earth (R. Janovsky). Orbital debris can be characterized by three distinct groups. The first group is comprised of accidental or intentional break-ups. The second major category is the intentional release of objects from launch vehicles and spacecraft during deployment. The third and increasingly more common cause of debris is the in-orbit collision of space debris (Office for Outer Space Affairs). These three separate categories may result in objects that have lifetimes on the order of decades.
The United Nations Office for Outer Space Affairs has prescribed a series of guidelines which are designed to mitigate orbital debris. The guidelines are as follows:
Limit debris released during normal operations
Minimize the potential for break-ups during operational phases
Limit the probability of accidental collision in orbit
Avoid intentional destruction and other harmful activities
Minimize potential for post-mission break-ups resulting from stored energy
Limit the long-term presence of spacecraft and launch vehicle orbital stages in the low-Earth orbit (LEO) region after the end of their lifetime (Office for Outer Space Affairs)
These new mandates, specifically guideline six, require that launch vehicles and their payloads must have a timely return to earth at the conclusion of their mission. Additionally, the Inter-Agency Space Debris Coordination Committee (IADC) along with NASA and the International Standards Organization (ISO) put a limit on orbital lifetimes for Low Earth Orbit (LEO) of 25 years (IADC).
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