If We Had SNAPS and Could See a Picture of Our Deployment, That Would Have Been a Game

Proposal Details

“If we had SNAPS and could see a picture of our deployment, that would have been a game changer” – Walter Holemans, Planetary Systems Corporation

Overview

The Stanford Nano Picture Satellite (SNAPS) is a 0.25U CubeSat created by a team of Stanford undergraduate and graduate students. SNAPS’ mission is to deploy from the same dispenser as a 3U cubesat, take video of the cubesat, and send images of its deployment back to Earth. These images are valuable data for satellite operators who need to know how their satellite has deployed. The project has been worked on for approximately a year; we are seeking a launch in early 2015.

Background

The Canisterized Satellite Dispenser (CSD) is an alternative to the Poly-PicoSatellite Orbital Deployer(P-POD) for deploying CubeSats. The CSD standard is a compelling alternative to the P-POD because it enumerates specifications for robust mechanical constraint of satellites using “sandwiched” tabs, the size and mass of satellites, and a satellite-to-vehicle interface. Critically for SNAPS, the CSD standard has one extra inch of space compared to the P-POD. The SNAPS satellite fits in this extra 1 inch of space along with a typical 3U Cubesat, allowing it to add tremendous value with little additional cost or risk.

Mission Phases

The SNAPS mission consists of four phases.

1)SNAPS and a CubeSatdeploys from a CSD. As mentioned above, SNAPS fits into the CSD deployer along with a 3U cubesat.

2)SNAPS takes video of the cubesat deployment. SNAPS’ camera is automatically turned on as deployment from the cubesat begins. SNAPS has a 1080p HackHD camera which will take video for 10 minutes after deploying. Video will be saved to a SD card on SNAPs.

3)SNAPS software analyzes which video frames include image of cubesat deployment. SNAPS’ image processing algorithm identifies the satellite by searching the frames of the video for hard edges. This algorithm will run on-orbit on SNAPS’ processor.

4)SNAPS transmits video frames identified in Phase 3 to ground station. SNAPS transmits with an omnidirectional antenna built into the body of the satellite. It is expected that the first image will arrive in about 2 days. All images will be downlinked in 1 month.

SNAPS Mission Parameters

SNAPS has a wide orbit altitude and inclination range because its primary mission is to take video of the 3U CubeSat it deploys with. The primary limitation is that the orbit must have line of sight with Stanford because that is where SNAPS’ ground station is located.

CubeSat Mission Parameters
Mission Name / Mass / Cube Size / Desired Orbit / Acceptable Orbit Range / 325 km @ 51.6° incl. Acceptable / Readiness Date / Desired Mission Life
SNAPS / <1.33 kg / 0.25 U (10x10x2.5 cm) / Altitude / 300 km / 200km - 500km / Yes / 1/1/2015 / 3 months
Inclination / 40° / 20° - 60°

Cubesat Project Details

CubeSat Project Details
Focus Area / Student Involvement / NASA Funding / Sponsor / Proposed Collaboration
Yes or No / Organization / Yes or No / International – Yes or No
1)Primary - Technology
2)Secondary -Educational / Yes / No / N/A / Stanford Student Space Initiative / No / No

Merit Review Process

We believe SNAPS provides tremendous Technical and Educational merit to NASA. To verify our beliefs, we conducted a merit review by meeting in person with individual members of our merit review committee. The members of the committee are listed in the table below and were selected due to their experience in space technology and education. The process was not competitive as there were no other Stanford groups to our knowledge building a cubesat. Results of the merit view are discussed after both the Technical and Educational merit sections.

Name / Experience
Scott Hubbard / Consulting Professor in Aeronautics and Astronautics at Stanford
Former Director, NASA AMES
Gil Moore / Project Director, Polar Orbiting Passive Atmospheric Calibration Sphere
Andrew Kalman / Consulting Professor in Aeronautics and Astronautics at Stanford
Founder, Pumpkin, Inc. (makers of the CubeSat Kit)
Ivan Linscott / Senior Research Associate at Stanford
Walter Holemans / Chief Engineer, Planetary Systems Corporation (creators of the Canisterized Cubesat Dispenser)
Marcos Pavone / Assistant Professor in Aeronautics and Astronautics at Stanford

Project Focus: Technical Merit

As a technology demonstration mission, SNAPS solves a very specific need in the cubesat market while also serving as a stepping stone towards valuable larger missions. This mission advances NASA’s technology strategic goals of “Extending and sustaining human activities across the solar system” and “sponsoring early-stage innovation in space technologies in order to improve the future capabilities of NASA, other government agencies, and the aerospace industry.”

Value of Imaging other Satellites

SNAPS’ specific mission will demonstrate the ability for a CubeSat to take pictures of another satellite, a previously unperformed feat that is useful for numerous reasons.

First, by taking pictures of deploying cubesats, SNAPS provides critical information on the initial conditions of the photographed CubeSat’s trajectory and spin that significantly increases the likelihood of mission success. Currently, there is almost no information as to what happens to a CubeSat when it is deployed, and this has resulted in numerous failed missions as communication is lost or the data received is incomplete. Even when satellites are working, understanding their deployment is critical. For example, the Polar Orbiting Passive Atmospheric Calibration Sphere (POPACS) mission consisted of three spheres separated by spacers (Figure 1). In our merit review, the project director for the mission told the SNAPS team that having images would have been critical in determining whether they deployed correctly, something they could otherwise only estimate.

Second, SNAPS is useful for diagnosing satellite issues. When something goes wrong on a satellite, the ground team has to use sensor data to try to determine the issues; often, the necessarily information is not available and being able to obtain real time imagery or video of the satellite would enable the ground crew to better assess the situation. For issues like a mechanical failure of a solar panel deployment, anomalies caused by being struck by space debris, or mistracking of satellites, especially in LEO because of drag, real time images would be the fastest way to identify the problem, saving significant troubleshooting and failure costs.

Finally, this technology can advance other increasingly important space technologies or maneuvers, such as docking, telerobotics, or satellite servicing. By providing views from different angles, inspector satellites like SNAPS can increase the machine’s or ground crew’s awareness of the situation, helping to enable rapid and informed decision making.

Value of Miniaturization

As a ¼-U satellite with tremendous functionality, SNAPS also functions as a technology demonstration of the increasing ability of miniaturized spacecraft to leverage advances in commercial off the shelf (COTS) electronics. To our knowledge, SNAPS’ flight computer, camera, and antenna are more powerful than any equivalent hardware that has been used by a CubeSat that has flown in space.

SNAPS’ main flight computer runs through a 32 bit ARM microcontroller, a state of the art processor used in the majority of mobile phones. It is powerful and easily upgradable as the rest of the board is made of entirely of COTS technology as well.

The video camera on board is a 1080p HD camera with a 160-degree wide view lens that has extremely high resolution for its size. Again, this enables higher quality than other CubeSat cameras and builds off state of the art, COTS technology. Moreover, the wide view ensures that SNAPS will capture imagery of the other satellite.

Lastly, the folded dipole antenna that SNAPS utilizes to communicate back to Earth adds huge capability and reliability to small satellites. By folding around the body similar to the antenna of a smartphone, SNAPS’ antenna can communicate omnidirectionally at high frequencies without taking up much space within the satellite or requiring advanced technologies. Most small satellites require deployable antennas and accurate pointing and satellites have failed when either the stabilization or deployment mechanism has failed or interfered with other satellites. The folded dipole removes this possibility and increases both the performance and likelihood of mission success.

Value of the Mission Architecture

By deploying with another satellite and using its mission to advance the mission of the photographed satellite, SNAPS will be an early demonstration of co-orbiting satellites that complement each other and achieve more together than either satellite could achieve alone. This is a stepping stone for formation flight of cubesats, which will allow advanced missions to be accomplished at low cost.

Moreover, SNAPS demonstrates the potential of the CSD as a cubesat deployer and expands the potential of that platform by integrating seamlessly and allowing CubeSats using the CSD greater mission flexibility. The team plans to expand SNAPS to serve 6U and larger CSD’s, allowing greater capabilities and further increasing the potential of both platforms.

Technical Merit Review Recap

All members of the review committee saw that there was tremendous technical merit in SNAPS. Hubbard was excited about SNAPS as a way to increase the reliability and prove the capabilities of secondary payloads. Hubbard also recommended we look at specific use cases, so we spoke with Holemans and Moore in greater detail about how SNAPS would have helped the POPACS mission.

Holemans and Moore were very excited about the possibility of getting images of cubesats to help identify initial conditions and increase the chance of mission successes. Moore reported that for the POPACS mission that he led, a tremendous amount of time and energy was put into tracking the spheres and trying to estimate what happened as they were deployed from the CSD, something SNAPS’ pictures would have determined immediately. Holemasconfirmed and added “If we had SNAPS and could see a picture of our deployment, that would have been a game changer.”

Holemans, Kalman, and Linscottagreed that the cutting edge microcontroller, camera, and especially the breakthrough with the folded dipole were huge steps forward for smaller, more capable satellites that really built off the movement to miniaturize electronics. Pavone was particularly interested in SNAPS as a stepping stone towards larger missions where this miniaturized camera payload could be combined with more advanced controls systems to allow pictures to be taken of other satellites and missions, greatly increasing our capabilities.

Secondary Focus: Educational Merit

Our goal with SNAPS is to create a process where university students can launch productive cubesats with the highest chance of success and implement a system to teach this process to future students at Stanford and at other universities. The team recognizes that many university cubesats have failed, so creating this process will add a lot of educational value. We can accomplish NASA’s goal to “Strengthen NASA and the Nation's future workforce” by teaching future engineers our process, which will give them hands-on training with a functioning satellite. Several features of the SNAPS mission increase our educational impact.

Accessibility and Reproducibility

All SNAPS documentation and learning is published on an open website ( This means that the learnings and successes of the SNAPS team can be passed on to other educational institutions or new generations of satellite makers. We have already seen evidence of this learning as the final reports written by the SNAPS team last year (see Appendix) were instrumental in getting the current SNAPS team up to speed. Furthermore, the SNAPS structure is created with additive manufacturing. The computer-aided design files are available for download here: This means that future satellite makers can easily 3D print the satellite structure.

Fast Iteration

Our team believes that our educational value is amplified by our ability to iterate rapidly, constantly testing and getting expert feedback. Because we use COTS components, we can rapidly change hardware and test our current designs. For example, we are using a Lithium Li-1 radio, but we can easily replace it with the next generation Li-2 radio if necessary as we experiment with the folded dipole and the required range. In addition, we 3D print structures so we can try different designs the day they are completed. These learnings become a part of our educational process because the team produces a report summarizing our findings every 3 months, which is then presented to students and faculty.

Multidisciplinary Student Pipeline

The SNAPS core team currently consists of 8 Stanford students, from Freshman to PhD students. By involving students of all educational levels, the SNAPS team will not be lost by a single graduation cycle, and experience can be passed directly onward. We have concrete evidence of this as some of the students who worked on SNAPS last year have graduated, yet the SNAPS team remains strong. Furthermore, we have students from a variety of Stanford departments, including Aeronautics and Astronautics, Electrical Engineering, Computer Sciences, and the Graduate School of Business. This lets students exchange their ideas and learn more about how to work in a cross-functional environment.

Educational Merit Review Recap

Linscott pointed out that many university cubesats failed, so it would be truly valuable for education if we could create a process that would maximize the chances of success. He also praised our iteration cycles and recommended we expand on them. As a result of his feedback, we committed to the open architecture of SNAPS where we publish everything on our webpage and expanded our testing plan. We believe this will maximize the learning for ourselves and other institutions.

All of the committee members thought the open-source nature of the project had the ability to have an educational impact beyond the Stanford students who are working on it. Hubbard thought the project was more educational because it involved multiple Stanford departments. He encourages us to reach out to even more departments. To address this, we have a recruiting effort underway to bring more students into the project, including non-technical students who can help with regulatory and licensing requirements.

Technical Feasibility

This section describes the technical work for each subsystem in SNAPS that either has been completed or needs to be. As an overview, SNAPS’ mechanical, electrical, and communications designs have been developed and are largely complete. SNAPS software is partially complete: the imaging algorithm is complete, but the flight software and ground station components have to be developed. Finally, SNAPS has to undergo a variety of testing, including thermal, vacuum, and vibration testing.

Structural Subsystem

SNAPS' structure has been designed and built. It consists of two parts, a bottom shell that houses all of the components and a top plate which snaps on top. The two sections are then screwed together to keep everything fully constrained. The shells can either be 3D printed or machined. There are grooves in the bottom shell to locate the HackHD camera, two batteries, aluminum tabs, and three switches needed to ride in the CSD. Standoffs place the battery protection and main C&DH boards at the right heights and screw slots hold the camera, boards, and aluminum tabs in place. The aluminum thermal plate snaps and screws into the top plate to sit ontop of the radio and batteries to transfer heat between them. There is a slot in the bottom shell that houses the antenna and both large faces have recesses to hold two solar panels.

The 3D printed body lets us rapidly iterate on the design. Several iterations of the structure have been printed and fully assembled to verify that everything fits. The onlyremaining task is final integration of the tuning board to connect the antenna and radio.

Electrical Subsystem

SNAPS is powered by four solar panels mounted on the face and back of the satellite. The output of the solar cells is used to power two batteries arranged in parallel. The main sources of power consumption are the HackHD camera and the radio.

Already Completed

Component / Estimated Power Consumption (W)
Camera / 5.52
SD card / 0.28
Radio / 5.43
Processor / 0.40
Processor (sleep) / 0.06
Maximum possible / 11.7

Power budget analysis and power management circuitry have already been completed for SNAPS (see Table 1). There are four possible modes of operation: recording (camera + processor + SD card active), processing (processor + SD card active), transmitting (processor + SD card + radio active), and sleep (all electronics sleep). Estimated power consumption for each component is listed below.

The radio accounts for 91% of all energy usage assuming a 180 day mission. Thus, the RF link budget heavily influences the total power budget. Using STK, the team estimated that a balanced energy budget dictates a 7.5% RF duty cycle.

To be done

The team’s main task before the electrical systems are complete is to assemble and characterize the solar cells and their maximum power point tracking (MPPT) system. Three versions will be constructed for testing: solar cells only, MPPT circuitry only, and solar cells and MPPT circuitry together. As of writing, the solar cells only version and combined version are fully complete, and the MPPT only version is partially completed.