The STF-1 team has been hard at work constructing a custom mount for the camera this week. This mount will keep the camera firmly in place throughout the vibrations experienced during launch. A Computer Numeric Control (CNC) machine was utilized to cut the mount out of a solid aluminium block. The picture below displays a close-up of the machine in action!
The CNC machine takes in a special type of code, G-Code, which provides instructions for how to cut the part. This includes things like where to move, how fast to move, what path to follow, and what bit to use for the operation. G-Code is typically automatically generated from a computer model to ensure that the dimensions of the component are correct. The final product can be seen attached the the ArduCAM OV2640 Mini below. The mount will attach directly to the side of the chassis while the camera will plug into the special services card allowing it to communicate with the computer.
The STF-1 team has been involved with a number of small satellites missions from Goddard since the proposal process. Similar components were utilized across missions to provide additional support and spare parts between us. Last week the STF-1 team was called upon to share the engineering test unit (ETU) electrical power system (EPS) from ClydeSpace. In order to do this the flat sat had to be taken apart. The “flat sat” is a technique used to test how all the components work with one another on a table-top instead of in a chassis. This allows for more simple debugging and setting up of test configurations. An example picture of what this looks like is below:
With all of the components taken apart, it was the perfect time to do some impromptu tours for our co-workers at NASA IV&V. Approximately 30 people came to visit the clean room and get a feeling for the actual size of the components and spacecraft itself as well as ask interesting questions. STF-1 has once again created a flat sat, but this time with a battery in the loop as well to provide yet another data point for testing. Once a few more tests are complete, it will be time for integration into the chassis!
The STF-1 team has been busy over the past weeks working with the Computer Science and Electrical Engineering (CSEE) department at West Virginia University. During this time hardware, firmware, and software updates had been made to allow for integration of the payload into the STF-1 stack. The video below shows one of the two boards in the payload triggering, or flashing the LEDs, as a response from the flight computer.
The LEDs shown are specially made using Gallium III-V Nitride-based materials at WVU. The payload is set to test the amount of shielding needed in the harsh environment of space to allow use for short-range distance measurement and shape rendering. The second board (not shown) utilizes photo diodes to provide the measurements needed for the experiment over the duration of the mission.
The STF-1 team continued progress on various components of the spacecraft during the past week. The WVU Physics and Astronomy department is contributing an instrument to analyze space weather in the ionosphere. The instrument contains a Langmuir Probe for measuring properties of plasma and a Geiger counter for measuring ionizing radiation.
During the past week, the final flight board assembly was completed and testing of the firmware for the microcontroller and of the hardware was executed in the physics lab in White Hall at WVU. The various components that will eventually comprise STF-1 each must be tested in isolation prior to being ready to integrate into the chassis and then the entire spacecraft being tested.
The pictures below show instrument testing at the lab. If you look closely, you can see the cylindrical end of the Geiger counter sticking out between the two circuit boards. Note also the various leads connected to the board and the external instruments needed for performing stimuli and taking measurements during testing. (Photo credits: Mark Suder)
The STF-1 team has begun unit testing the ISISpace Antenna System (AntS) in the cleanroom this past week. The AntS is made up of four individual elements that deploy when commanded from the on-board computer. These elements can be in a multitude of configurations, but STF-1 will be utilizing the dual dipole. This means the each antenna is linked with the one directly across from it.
The picture above shows the antennas are rolled up and ready for deployment. Each antenna has a burn-wire that holds it closed. When activated the resistors underneath this wire will heat up and cause the wire to break and allow the springs to open the door. Each antenna is actually the same material as a tape measure with similar properties. STF-1 will use one dipole (or set of connected antennas) to communicate with the ground station and the other as a Langmuir probe to perform experiments for the Physics department at WVU.
Each antenna can only be deployed twice, once on the ground and once in space. Because of this, video was taken to document the process.
The STF-1 team made the decision early on to leverage the efforts of another Goddard CubeSat mission, Dellingr, in components used. This included custom designed solar panels created in house. Interns at GSFC spent a summer perfecting the process of designing and building these solar panels. This includes printed circuit board (PCB) design, construction materials and process, as well as how to test a panel is fully functional and ready for flight.
The picture above shows STF-1’s technical lead, Matthew Grubb, preparing to solder the silver connector onto the solar cell to allow for a connection to the PCB. STF-1 will have up to seven of these cells connected in a row attached to the board only by the four solder pads and a special type of tape underneath each cell. Below you can see the completed solar panel and these connections. The temperature sensor (empty pad in the picture) will be added and tested before flight as well.
Members of the STF-1 team have been visiting Logan, Utah, home of the Space Dynamics Laboratory (SDL) and Utah State University for the small satellite conference. This conference spans a week including a weekend workshop dedicated to CubeSat Developers where Matthew Grubb presented on the NASA Operational Simulator for Small Satellites (NOS3).
NOS3 is an open source platform merging in various GSFC technologies into one package. These include 42, cFS, COSMOS, and NOS Engine. A full presentation can be found on the smallsat.org website for download. Additional presentations on cFS can be found as well. Goddard Space Flight Center also had a booth at the conference presenting on all the current and future planned CubeSat missions such as Dellingr, IceCube, CUTIE, and STF-1. This included 3D printed models and videos showing simulations of the spacecraft and the assembly process.
How important are the L-3 Cadet Radio and the ISISpace Antenna to STF-1? No matter how fascinating the results of STF-1’s multiple experiments are, they aren’t worth anything at all if we can’t view the results on Earth. Because of this, the radio and antenna are vital to mission success. The radio’s “store and forward” capability is what allows it to store up to 4GB of experimental results throughout each orbit, before forwarding the results to the ground station when it is in sight. Additionally, the radio is equipped with a microprocessor that allows the ground team to communicate with STF-1’s on board computer. Ultimately, this system allows the CubeSat to relay data findings and receive commands from the ground team, making it one of the most important systems on West Virginia’s First Spacecraft.
Recently, the STF-1 Team received both the radio and the antenna that will be used in conjunction with it. Pictured below (top), the team runs an initial checkout on the L3 Cadet Radio, while they look over the ISISpace Antenna (bottom).
If you’d like to learn more about the four science experiments STF-1 will be carrying out in space, make sure to check back on this website over the course of the next several weeks for our new video blog series, where we will interview each of the four teams responsible for the four science objectives on STF-1. Below is a list of each team and their project:
WVU Mechanical and Aerospace Engineering – GPS and IMU (Inertial Measurement Unit)
WVU Physics and Astronomy – Space Weather
WVU Lane Department of Computer Science and Electrical Engineering – III-V Nitride Materials
NASA IV&V – Earth Science Camera
While some of these topics may look fairly intimidating, there’s no need to worry. Each of these teams will be explaining their project in terms that we can all understand! Lastly, make sure to get involved with the video blogs by submitting any questions you have for the scientific teams to John.P.Lucas@ivv.nasa.gov. Before each video, we’ll select a couple of the best questions to ask the team we’re interviewing!
While STF-1 will be hitching a ride up to the thermosphere on the Electron, once it is deployed, a constant electrical power supply will be necessary for each of its scientific experiments to be carried out successfully. From the GPS to the camera to the radio, most everything on STF-1 requires electrical power to ensure that it functions properly. However, due to the standardized size and weight of CubeSats, STF-1 could never carry enough batteries to power its entire mission. It doesn’t have nearly enough volume, and it’s only allowed to weigh 4 lb! Instead, STF-1 uses 5 solar panels – which are placed on all faces but the bottom – to provide power to the other systems. After converting the sun’s rays to electricity, the solar panels pass the electricity to the ClydeSpace EPS, which stores them in the batteries. Then, the EPS has the ability to send electricity from the batteries to various systems in STF-1.
It doesn’t take long to realize that the role that the ClydeSpace EPS plays is a major one, and that the mission can’t afford any mishaps with the EPS’s capabilities. A failure in the EPS would almost certainly result in subsequent mission failure. Above, the STF-1 team performs an initial checkout of the Electronic Power Supply using a laptop, an Aardvark (host adapter), and a power supply. The power supply (pictured in back) simulated the input of electricity that would have been provided by the 5 solar panels. Then, I2C commands were sent from the laptop through the Aardvark to test the EPS. Ultimately, the team found that the EPS functioned well, meaning that it is ready for future hardware testing and that we’re one step closer to putting WV’s First Spacecraft into space!
The STF-1 team has received all the core components from the various vendors. These include the chassis and radio from ISISpace, power system from ClydeSpace, radio from L3, and flight computer from GomSpace. All of these have been inspected and weighed in because weight is a major concern with something so small. NASA and all launch service providers like to keep the weight as low as possible so that it is easier and cheaper to get everything into space.
The GomSpace flight computer with motherboard is pictured above. This little board is about the size of a credit card and will do all the processing including running our operating system, Free Real Time Operating System (FreeRTOS), and the Core Flight System (cFS) with all our applications to collect and process science data. This isn’t the only computer on-board, but any data that we want on the ground will have to pass through this one!