| Cornell University Satellite | |
| Names List: | CUSat |
| Mission Type: | Technology demonstration |
| Operator: | Cornell University/AFRL |
| Cospar Id: | 2013-055B |
| Satcat: | 39266 |
| Website: | At Cornell.edu |
| Manufacturer: | Cornell Space Systems |
| Launch Mass: | 40.82kg (89.99lb) |
| Launch Rocket: | Falcon 9 v1.1 |
| Launch Site: | Vandenberg Air Force Base |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Low Earth Orbit |
| Apsis: | gee |
The Cornell University Satellite (CUSat) is a nanosatellite developed by Cornell University that launched on 29 September 2013. It used a new algorithm called Carrier-phase Differential GPS (CDGPS) to calibrate global positioning systems to an accuracy of 3 millimeters. This technology can allow multiple spacecraft to travel in close proximity.[1]
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 Aerospace Engineering Facility at Kirtland Air Force Base. CUSat worked with AFRL to complete the Department of Defense SERB process in preparation for a launch with the Space Test Program. The satellite launched as a secondary payload to CASSIOPE on a SpaceX Falcon 9 rocket on 29 September 2013.[2]
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 (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, 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.
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.
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.
Once an attitude control was obtained, CUSat's actuators 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
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.
At the time of its launch in 2013, it was estimated that 200 Cornell University students had participated in the project since it began in 2005.[3]
The Principal Investigator for the CUSat project is Mason Peck. The two advisors for the CUSat project are Mark Campbell and Mark Psiaki.
Because CUSat is an engineering project team at Cornell University, 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, Mechanical and Aerospace Engineering, Applied and Engineering Physics, Computer Science, Economics and Management, and even Architecture.
There has been a major redistribution of work, into different subsystems since FCR. The current subsystems are listed below.
The ground segment was responsible for the ground operations of the satellite, including ground to satellite communication, tracking and commanding.