A University Deep Space CubeSat Mission: Lessons Learned from the University of Colorado Boulder Earth Escape Explorer (CU-E3)

The University of Colorado Boulder Earth Escape Explorer (CU-E3) CubeSat is a student designed and built CubeSat initially slated for launch into deep space on Artemis-1, the inaugural launch of the NASA Space Launch System (SLS). CU-E3 was designed to compete in the Cube Quest Challenge’s (CQC) Deep Space Derby for monetary prizes associated with deep space communication system performance, while also serving as a technology demonstration platform for a series of innovative university CubeSat technologies and practices, including a low-cost X-band CubeSat transmitter, an X-band reflectarray antenna, and the use of solar radiation pressure to control reaction wheel momentum build-up. An overview of the CU-E3 project, including mission concept of operations, system architecture, and major component descriptions are provided. Emphasis is focused the challenges and lessons learned as a participant of the CQC with a student designed and built deep space CubeSat. These challenges include student turnover, limited commercial ground station capabilities and availability, deep space thermal environment, secondary payload safety procedures for the human space rated SLS, and deep space trajectory variance

The First Solution to the Lost in Space Problem

In December 2018 and January 2019, weeks after a successful fly-by of Mars and relay of the InSight landing, communication with the MarCO cubsats were lost. The causes of this loss of communications with the MarCO cubesats are unknown, but could be related to a power issue or onboard fault. This leaves the MarCO cubesats effectively, lost in space, having no way to autonomously recover time, position, or velocity, should the spacecraft recover from the anomaly. This research will show a full solution to the lost in space orbit determination problem. This solution is achieved by using self-acquired optical observations via cubesat star tracker, of the planets, moons, and stars, thereby re-initializing the mission operations using low size, weight and power sensors compatible with small spacecraft architecture. Such cases of a lost in space spacecraft have not been systematically investigated until now. This research will show that it is indeed possible to solve this problem, recovering time, position, and velocity, and will show analysis in the context of the high precision requirements of planetary missions. Using the MarCO architecture and hardware as a baseline, this research will present a solution based on the orbital parameters of the MarCO cubesats

Guest Editorial: The 2014 Capstone Design Conference

The goal of the 2014 Capstone Design Conference held in Columbus, OH was to build upon the success of three previous conferences (2007 and 2010 in Boulder, CO, and 2012 in Champaign, IL) and expand the community of educators, students, and industry members engaged in discussing, analyzing, and improving capstone design education. Sessions at the 2014 Capstone Design Conference were designed for vibrant sharing of ideas and experiences across the capstone community via interactive panel sessions, poster session socials, and hands-on workshops. This editorial discusses conference planning, structure, and feedback. Technical papers that follow in this issue document scholarship surrounding noteworthy capstone course innovations. Most of these began as four page peer-reviewed papers included in the conference proceedings

Simulation of a High Stability Reference Clock for Small Satellites with Modeled GPS Timing Errors

Small satellites have become capable platforms for a wide range of commercial, scientific and defense missions. Improved onboard clocks would make small satellites a viable option for even more missions, enabling radio aperture interferometry, improved radio occultation measurements, high altitude GPS navigation, and GPS augmentation missions, among others. Previous research by the authors investigated methods for creating a high stability reference clock for small satellites by combining a heterogeneous group of oscillators including multiple CSACs, a GPS receiver and an EMXO. This work predicted that time error standard deviations of ~500 ps were possible with GPS timing errors modeled as AWGN. This paper builds on previous work by developing a high-fidelity model for the GPS receiver timing error onboard a LEO spacecraft. Signal-In-Space Ranging Errors (SISRE) are modeled using post-fit GPS orbit and clock data, and ionospheric delays are approximated using IONEX maps and ionosphere models. GPS point solutions are then calculated over several days of LEO orbits to generate realistic receiver timing errors, which were then used in simulations of the high-stability heterogeneous clock ensemble. Simulations show degraded clock system performance compared to the prior model, with standard deviations of time errors increasing to 1.3 ns 1-σ. The results provide insight into the nature of GPS receiver clock errors for LEOs, as well as practical limitations that should be expected when implementing advanced clock systems on small satellites

Cobalt: The Next Step in Low SWaP-C Optical Terminal Design

Blue Cubed has developed Cobalt, a full duplex optical terminal which can support both symmetric crosslinks and downlinks. The system has been engineered to be modular, easily mass produced and available at a competitive price. Cobalt is intended for low earth orbit small satellite applications that require 100 Mbps to 10 Gbps per communication links at ranges of up to 4000 km. The Cobalt core transceiver (excluding the telescope) is roughly 0.5U (9 x 9 x 5 cm), one kilogram, and consumes 10 W of electrical power for the 3 Gbps system variant. An increased data rate can be achieved by adding up to three (3) additional 3 Gbps channels which adds 3W of additional power and 100 g of additional mass per channel. The link performance is a function of the radiometery where data rate, telescope size (11 mm to 100 mm) and range can be traded. A gimbal which provides hemispheric coverage and meets the needs of the growing satellite constellation market is also currently under development. The Cobalt optical bench incorporates a novel, patented1 self-alignment technique based on differential tracking of the transmit and receive signals. This approach greatly relaxes manufacturing tolerances and makes the bench uniquely robust to environmental loading. While the self-alignment approach is applicable at any wavelength, Blue Cubed has focused initial development on a 850 nm variant. Silicon-compatible wavelengths offer low cost and high-performance detectors, tracking sensors, and lasers, all of which are critical in highly SWaP and cost constrained applications. Cobalt can be paired with the Bluefin X-band transmitter to provide a hybrid RF and optical downlink terminal. In this talk we describe the status of the Cobalt transceiver, share laboratory test results and discuss our path to initial on-orbit demonstrations targeted for late 2023

The Design, Analysis and Testing of Low Cost Dual Deployable Solar Panels for Small Satellite Missions

The National Science Foundation (NSF) funded university small satellite mission, Space Weather Atmospheric Reconfigurable Multiscale Experiment (SWARM-EX) is designed to address outstanding aeronomy and space weather questions while demonstrating swarm behavior in constellations of six to twelve 3U CubeSats. SWARM-EX is limited in power, which requires the use of dual-deployable solar panels in order to maximize the number of solar cells powering the small satellite. Commercial off the shelf (COTS) dual-deployable solar panel options tend to be expensive, necessitating the creation of custom-built, dual-deployable solar panels. The design of the dual-deployable solar panels is constrained in volume, manufacturability, and survivability of the launch conditions. In the stowed launch configuration, the full smallsat assembly must fit in an 88 mm by 326.1 mm by 9 mm space. The dual-deployable solar panel assembly must also be able to withstand the vibroacoustic launch environment. The launch environment requires withstanding a vibroacoustic load of 10 Grms for one minute in each axis. The solar panel assembly underwent testing in order to ensure the system operates as expected during the mission. Deployment testing will be conducted, and vibrational testing is planned for six months before launch

A Compact Five-Channel VLF Wave Receiver for CubeSat Missions

Very low frequency (VLF) waves play an important role in controlling the evolution of energetic electron distributions in near-Earth space. This paper describes the design of a VLF receiver for the Climatology of Anthropogenic and Natural VLF Wave Activity in Space (CANVAS) CubeSat mission, designed to make continuous observations of VLF waves in low-Earth orbit originating from lightning and ground-based transmitters. The CANVAS VLF receiver will observe five components of VLF waves in the 0.3–40 kHz frequency range, using three orthogonal magnetic search coils deployed on the end of a 1-meter carbon fiber boom and four deployable electric field antennas operated as two orthogonal dipoles. Together, these five wave components will be used to calculate real and imaginary spectral matrix components using real-time fast Fourier transforms calculated in an onboard FPGA. Spectral matrix components will be averaged to obtain 1 second time resolution and frequency resolution better than 10%. The averaged spectral matrix will be used to determine the complete set of wave parameters, including Poynting flux, polarization, planarity, and k-vector direction. CANVAS is currently in the manufacturing and assembly phase and is planned to launch at the end of 2022

CubeSat Radiation Hardness Assurance Beyond Total Dose: Evaluating Single Event Effects

Radiation poses known and serious risks to smallsat survivability and mission duration, with effects falling into two categories: long-term total ionizing dose (TID) and instantaneous single event effects (SEE). Although literature exists on the topic of addressing TID in smallsats, few resources exist for addressing SEEs. Many varieties of SEEs exist, such as bit upsets and latch ups, which can occur in any electronic component containing active semiconductors (such as transistors). SEE consequences range from benign to destructive, so mission reliability can be enhanced by implementing fault protection strategies based on predicted SEE rates. Unfortunately, SEE rates are most reliably estimated through experimental testing that is often too costly for smallsat-scale missions. Prior test data published by larger programs exist, but may be sparse or incompatible with the environment of a particular mission. Despite these limitations, a process may be followed to gain insights and make informed design decisions for smallsats in the absence of hardware testing capabilities or similar test data. This process is: (1) Define the radiation environment; (2) identify the most critical and/or susceptible components on a spacecraft; (3) perform a search for compatible prior test data and/or component class data; (4) evaluate mission-specific SEE rates from available data; (5) study the rates alongside the mission requirements to identify high-risk areas of potential mitigation. The methodology developed in this work is based on the multi-institutional, National Science Foundation (NSF) Space Weather Atmospheric Reconfigurable Multiscale Experiment (SWARM-EX) mission. The steps taken during SWARM-EX’s radiation analysis alongside the detailed methodology serve as a case study for how these techniques can be applied to increasing the reliability of a university-scale smallsat mission

New Constraints on Macroscopic Dark Matter Using Radar Meteor Detectors

We show that dark-matter candidates with large masses and large nuclear interaction cross sections are detectable with terrestrial radar systems. We develop our results in close comparison to successful radar searches for tiny meteoroids, aggregates of ordinary matter. The path of a meteoroid (or suitable dark-matter particle) through the atmosphere produces ionization deposits that reflect incident radio waves. We calculate the equivalent radar echoing area or `radar cross section' for dark matter. By comparing the expected number of dark-matter-induced echoes with observations, we set new limits in the plane of dark-matter mass and cross section, complementary to pre-existing cosmological limits. Our results are valuable because (A) they open a new detection technique for which the reach can be greatly improved and (B) in case of a detection, the radar technique provides differential sensitivity to the mass and cross section, unlike cosmological probes.Comment: Main text 14 pages and 11 figures, Appendix 2 pages and 3 figure