NASA Ames Suborbital Flight Communication

While the barriers to space flight have been reduced, one large hurdle still remains for those seeking to conduct research in space: communications. We seek to remove this barrier by using satellite phone modules to give cube satellites access to a constant internet connection, allowing them to stream data to earth without the need for users to apply for frequency licenses or to use prohibitively expensive equipment.

Additionally, our project looks to solve the current lack of recoverablility of satellites. Through the development of a Tube Deployed Re-entry Vehicle (TDRV), we will allow satellites a means of surviving re-entry so that equipment can be reused, or physical samples collected.

=Problem Definition=

Specifications
This project shall develop the hardware and software required to achieve a live network connection from a cube satellite in low earth orbit to a remote ground-based server using the Iridium Core 9523 satellite communication module.

This project shall also further develop and optimize the Tube Deployed Re-entry Vehicle, a three-stage re-entry vehicle launched from an orbital payload at the Von Karman altitude.

=Design=

Mechanical Design


We made a number of improvements to team ACOM's design, including:
 * Replacing the felt material with ripstop nylon to increase the effectiveness of the descent arrestor;
 * Replacing replacing the rail-mounted endcap and nosecap with a press-fit design;
 * Reconstructing the interior to accept a configurable electronics tray;
 * Mounting the GPS and Iridum antennas on the endcap, in addition to the drop mechanism;
 * Introducing descent arrestor hard-stop stabs for deployment testing; and
 * Replacing the 3D printed body with a machined tube to improve the strength-weight ratio.

This design was tested to have a maximum velocity of 17.5 meters per second.

Electrical Design


The board contains an SAMD21 ARM Cortex-M0+ microcontroller.

The board provides two serial connections: one is connected to the microcontroller for normal use, and the other connected directly to the modem for testing.

The modem requires a 30W power supply to send data, so LR3959 boost converter was used to provide the necessary power from an 8V input.

Software Design


The library was designed to use a simple command/response packet system.

The library was designed to provide four modes of operation:
 * OFF, where the modem is disabled;
 * RAW, where all data packets are sent directly to the modem;
 * SBD, where all data packets are converted into Short-Burst Data packets, which is the format currently used; and
 * TCP, where all data packets are streamed over a TCP/IP connection, which is the primary goal of this project.

Two versions of the library were created. The first version is designed for use on a microcontroller and is optimized to use as little memory as possible. The second version is designed to run on a computer and provides debugging information to assist  future software development.

GitHub Repo

=Team Members=

=Additional Documentation=

Presentations: