Cornell University Satellite
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The Cornell University Satellite (CUSat) is a
nanosatellite A small satellite, miniaturized satellite, or smallsat is a satellite of low mass and size, usually under . While all such satellites can be referred to as "small", different classifications are used to categorize them based on mass. Satellites c ...
developed by
Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...
that launched on 29 September 2013. It used a new algorithm called Carrier-phase
Differential GPS Differential Global Positioning Systems (DGPSs) supplement and enhance the positional data available from global navigation satellite systems (GNSSs). A DGPS can increase accuracy of positional data by about a thousandfold, from approximately to ...
(CDGPS) to calibrate global positioning systems to an accuracy of 3 millimeters. This technology can allow multiple spacecraft to travel in close proximity. The CUSat project began in 2005 and was the winner of the University Nanosat-4 Program which aims to educate the future aerospace workforce and develop new space technologies. As part of this program, CUSat completed environmental testing and other aspects of final I&T in the
AFRL The Air Force Research Laboratory (AFRL) is a scientific research and development detachment of the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of direct-energy based aerospace warf ...
Aerospace Engineering Facility at
Kirtland Air Force Base Kirtland Air Force Base is a United States Air Force base. It is located in the southeast quadrant of the Albuquerque, New Mexico, urban area, adjacent to the Albuquerque International Sunport. The base was named for the early Army aviator C ...
. CUSat worked with AFRL to complete the Department of Defense SERB process in preparation for a launch with the
Space Test Program The Space Test Program (STP) is the primary provider of spaceflight for the United States Department of Defense (DoD) Outline of space science, space science and technology community. STP is managed by a group within the Advanced Systems and De ...
. The satellite launched as a secondary payload to
CASSIOPE ''Cassiope'' is a genus of 18 small shrubby species in the family Ericaceae. It is the sole genus in the subfamily Cassiopoideae. They are native to the Arctic and north temperate montane regions. The genus is named after Cassiopeia of Greek ...
on a SpaceX
Falcon 9 Falcon 9 is a Reusable launch system#Partial reusable launch systems, partially reusable, two-stage-to-orbit, medium-lift launch vehicle designed and manufactured in the United States by SpaceX. The first Falcon 9 launch was on June 4, 2010, an ...
rocket on 29 September 2013.


Operation details

The space segment was originally designed to consist of two functionally identical satellites that would launch together and separate on orbit in a target-inspector configuration. Once in orbit, CUSat would use microthrust Pulsed Plasma Thrusters (PPTs) and sub-centimeter level accurate carrier-phase
differential GPS Differential Global Positioning Systems (DGPSs) supplement and enhance the positional data available from global navigation satellite systems (GNSSs). A DGPS can increase accuracy of positional data by about a thousandfold, from approximately to ...
(CDGPS) to navigate the satellites to within ten meters of each other. The inspector satellite would use cameras to gather imagery of the target satellite while performing relative navigation. Target satellite imagery would be transferred to the
ground segment A ground segment consists of all the ground-based elements of a spaceflight, space system used by operators and support personnel, as opposed to the Satellite space segment, space segment and user segment. The ground segment enables management of ...
, where they would be used to reconstruct a three-dimensional model for the end user. The mission was modified after one of the segments was damaged during testing. It later consisted of a single satellite with multiple antennas that transmit data to each other.


Original plan


Phase One: Launch

CUSat launched as a secondary payload on a launch vehicle. Once in orbit and in the correct attitude, CUSat separated from the launch vehicle where it began Phase Two - the initialization.


Phase Two: Initialization

Once CUSat separates from the launch vehicle and enters the Initialization Phase, it will enter solar illumination where the spacecraft will power on. The spacecraft will make contact with the Mission Control Center at Cornell through one of several ground stations, beaconing its status. Next, the spacecraft will begin to assess its tumble rates, and will detumble if required. Once stabilized, CUSat will begin commissioning operations. Operators in the MCC will assess the health of most satellite subsystems. During this time, the top spacecraft will begin to search for surrounding GPS satellites. A Carrier-phase Differential GPS Lock is then acquired to obtain an accurate attitude solution. The spacecraft will enter Phase Three: Spacecraft Separation.


Phase Three: Spacecraft Separation

Once an
attitude control Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...
was obtained, CUSat's
actuator An actuator is a machine element, component of a machine that produces force, torque, or Displacement (geometry), displacement, when an electrical, Pneumatics, pneumatic or Hydraulic fluid, hydraulic input is supplied to it in a system (called an ...
s adjusted the attitude for a proper separation. While still in illumination, CUsat then performed a low-shock separation through the use of a lightband into Top and Bottom satellites. After separation, CUSat entered Phase Four: Inspection


Phase Four: Inspection

Once both Top and Bottom satellites obtained a GPS lock, the relative distance between the two was calculated via CDGPS. When the partner satellite entered an operational camera's field of view, the inspecting satellite acquired images of the partner satellite. The ground request specific images, which were subsequently downlinked from the space segment in the next communication opportunities. On the ground, the downlinked data was used to construct a 3D image of CUSat to verify the CDGPS data.


The team

At the time of its launch in 2013, it was estimated that 200
Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...
students had participated in the project since it began in 2005.


Administration

The Principal Investigator for the CUSat project is
Mason Peck Mason Peck is an associate professor at Cornell University and former NASA Chief Technologist. His immediate predecessor in the NASA position was Bobby Braun. Peck has published in various aerospace sub-disciplines including; air-bearing spac ...
. The two advisors for the CUSat project are Mark Campbell and Mark Psiaki.


Technical backgrounds

Because CUSat is an engineering project team at
Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...
, it is composed of a multitude of different students with a variety of abilities and talents. Team members come from such majors as
Electrical and Computer Engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...
, Mechanical and Aerospace Engineering, Applied and Engineering Physics,
Computer Science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...
,
Economics and Management Economics () is a behavioral science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyses ...
, and even
Architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and construction, constructi ...
.


Subsystems

There has been a major redistribution of work, into different subsystems since FCR. The current subsystems are listed below. *ADCNS: The Attitude Determination, Control, and Navigation Subsystem (ADCNS) executes the relative navigation that were to be used for CUSat's in-orbit inspection procedures. CUSat primarily used three
GPS The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geol ...
boards for attitude determination. For attitude control, CUSat used pulsed-plasma thrusters (PPTs) and
reaction wheels A reaction wheel (RW) is an electric motor attached to a flywheel, which, when its rotation speed is changed, causes a counter-rotation proportionately through conservation of angular momentum. A reaction wheel can rotate only around its center ...
. The software portion of ADCNS consisted of the relative navigation algorithms, which ran the various modes of operation defined by the CONOPs. *Camera: The camera team was responsible for acquiring images while in orbit, compressing them in a modified
JPEG JPEG ( , short for Joint Photographic Experts Group and sometimes retroactively referred to as JPEG 1) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degr ...
format, and relaying them to the onboard computer, C&DH. *Command and Data Handling: C&DH was the central hub for communication and computation on the satellite. Using a commercial off the shelf (COTS) single board computer running
Windows CE Windows CE, later known as Windows Embedded CE and Windows Embedded Compact, is a discontinued operating system developed by Microsoft for mobile and embedded devices. It was part of the Windows Embedded family and served as the software foun ...
and C++, C&DH executed the ADCNS algorithms and flight code. *GPS: The GPS team was responsible for the
GPS receivers A satellite navigation (satnav) device or GPS device is a device that uses satellites of the Global Positioning System (GPS) or similar global navigation satellite systems (GNSS). A satnav device can determine the user's geographic coordinates ...
, antennas and algorithms used to calculate sub-centimeter relative positioning. *
Ground Segment A ground segment consists of all the ground-based elements of a spaceflight, space system used by operators and support personnel, as opposed to the Satellite space segment, space segment and user segment. The ground segment enables management of ...
: The ground segment was responsible for the ground operations of the satellite, including ground to satellite communication, tracking and commanding. *Harness: The Harness subsystem was responsible for satellite wiring, the electronics backplane, the electrical interface boards, and any System level electrical concerns. *Industry Relations: The Industry Relations team was responsible for marketing CUSat and seeking commercial and academic sponsorship. *Integration and Testing: The I&T team was responsible for enabling rapid integration and testing of CUSat. I&T was also responsible for testing CUSat in Cornell University's thermal vacuum chamber. *Mechanical Hardware: The Mechanical Hardware team manufactured the satellite structure and managed the design. The structure included eight
isogrid Isogrid is a type of partially hollowed-out structure formed usually from a single metal plate with integral triangular stiffening stringers. It was patented by McDonnell Douglas (now part of Boeing) in 1975. Isogrids are extremely light and stif ...
panels as well as numerous electronics board enclosures. *Mission Ops: The Mission Ops team defined the detailed, on orbit operations plan for both CUSat satellites. Operating procedures were defined to match with hardware and mission specifications and help ensure successful execution of the mission. *Power: The power team was responsible for harnessing
solar energy Solar energy is the radiant energy from the Sun's sunlight, light and heat, which can be harnessed using a range of technologies such as solar electricity, solar thermal energy (including solar water heating) and solar architecture. It is a ...
, storing it, and distributing it throughout the satellite. *Propulsion: The propulsion team was responsible for CUSat's pulsed plasma thrusters (PPTs) which gave each satellite
six degrees of freedom Six degrees of freedom (6DOF), or sometimes six degrees of movement, refers to the six mechanical degrees of freedom of movement of a rigid body in three-dimensional space. Specifically, the body is free to change position as forward/backw ...
: three degrees of translational freedom and three degrees of rotational freedom. *Structures: The structures team was responsible for designing, analyzing, and manufacturing the body of the satellite as well as the logistics of the internal components. *Survivability: The Survivability team was responsible for analyzing and controlling the satellite's thermal, electrical and vibrational environment on the ground, during launch, and in orbit. Analyzed effects include ESD, atomic oxygen effects, venting and outgassing. *Systems: The CUSat Satellite project employed
Systems Engineering Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their Enterprise life cycle, life cycles. At its core, systems engineering uti ...
extensively. The Systems group was largely responsible for providing the project with direction by creating top level system requirements, creating best practices, maintaining communications, making design choices, and creating processes for creating a successful product. Each of the subsystem leads also participated as a member of the Systems group, which allowed the project to maintain consistency and focus. *Telemetry and Command: T&C was responsible for intersatellite communications as well as satellite to ground communications. T&C used modified commercial
radios Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to ...
operating in amateur frequency bands to transmit images acquired by the satellites to the ground station. The satellite was assigned the FCC
call sign In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. A call sign can be formally as ...
WG2XTI for amateur radio satellite service.


References

{{Use American English, date=January 2014 Student satellites Cornell University Spacecraft launched in 2013