RockSat X

Overview

What is RockSat-X?

RockSat-X is a competitive program put on by Colorado Space Grant Consortium  and NASA Wallops Flight Facility where schools are given an opportunity to perform experiments in space, with flight hardware that is designed and constructed by students.  Experiments in the past have ranged from collecting tiny meteorites to flying robots to taking debris out of Earth’s orbit. These experiments have a few limitations, however. They need to fit on a plate that’s 12” across – about the size of a big cast iron skillet – and be no taller than 5” or 10”, depending on the payload size the team purchases.  The experiments must also be fully autonomous, meaning that they can’t be controlled from the ground, so all the programming must be done beforehand. There is a limited amount of time, about 3 minutes, that teams can perform experiments. The rocket provides a limited supply of power to all the experiments on board. Past this point, teams have the liberty to test whatever they can imagine as long as they meet the restrictions. Given that there are limited slots on the rocket, teams’ experiments must pass a series of evaluations before being selected to fly on the rocket.  

What is Operation DUSTER?

Operation Debris Under Size 1cm Trajectory Edit for Removal (DUSTER) is the Colorado School of Mines RockSat-X team, which is also a Capstone team.  Our goal is to remove small pieces of debris from Earth’s orbit. When you think of debris from a satellite breaking up, or perhaps the Challenger space shuttle disaster, you probably think of most of the debris being large chunks that could cause problems.  Although these large pieces can cause space flight issues, they are a bit more obvious and easier to avoid. The more dangerous debris is the stuff you would probably never think of – things that are the size of BBs (from a BB gun), up to the size of a marble.  Debris that size seems harmless, but have you ever been shot with an airsoft or paintball gun? Pelted with a marble by your sibling or child? They can leave some pretty good welts. The particles of space debris are traveling at around 18,000 mph. This is about 80 times faster than a BB gun and fast enough to do some incredible damage to spacecraft trying to enter Earth’s orbit or go beyond. This is why Operation DUSTER is testing 3 different ways to alter the momentum of these small pieces of debris so that they leave orbit and burn up while falling through Earth’s atmosphere and are no longer a harm to potential space travel.

The Colorado School of Mines Rocksat-X team was established during the of Fall 2018 with the intention of being a multi-year, multi-team program, to design, develop, and implement innovative methods to change the trajectory of small scale space debris. This debris is small enough that it cannot be tracked using ground based systems and is one of the largest risks to current space missions. As such, the team intends to continuously build upon previous successes and failures in research and development, iterating design consistently as the project develops to solve this mission critical issue.

The first challenge of the team was determining how best to remove such small and untrackable debris from orbit. Concepts included: (1) collecting and housing the debris on a payload that could return the debris into Earth’s atmosphere, (2) launching the debris out of orbit and sending it to another orbiting system (such as the asteroid belt), and (3) redirecting the debris by changing the momentum so that it would fall into Earth’s orbit, burning up in the atmosphere and eventually destroying itself. 

Due to the high speeds of the debris (~18,000 mph), as well as the difficulty involved in a process which requires a container to transport debris back to earth, and the constraints of the payload size and weight, method (1) for removing space debris was abandoned as impractical and not realizable at this scale. Method (2) was likewise determined as impractical, due to the difficulty in finding ways to slingshot a particle out of Earth’s orbit if it’s impossible to track its trajectory and the risk of unintended consequences. 

On account of these limitations with the first two methods, the team decided to focus on the design of systems which would be capable of changing the momentum of untrackable space debris, allowing them to fall into Earth’s atmosphere. 

At the project genesis, five design concepts were initially considered as candidates for removing these untrackable space debris. These designs were analyzed based on several factors, including cost, feasibility to manufacture, and the ability to detect and deorbit the untrackable debris. These experiments included five methods for potentially altering particulate momentum: magnetic forces using a permanent magnet design, static electrical forces using capacitor plates, light momentum using the power of lasers, gas pressure with a compressed gas canister design, and contact interference using ballistics gel. 

Today, the first three of these experiment designs have survived analysis and bench-testing, and their successes and failures are discussed more in the Design Solution. The compressed gas and ballistics gel experiments were quickly abandoned however, due mostly to the hazards associated with their potentially explosive nature (and general concerns with putting an explosion-capable experiment into a flying object).

The overall mission further includes the development of a communication system. This communication system was designed with the intention of sending pictures from an onboard camera to a ground station, taking pictures of the payload with Earth proudly in the background. Difficulties in the physical realization of this system also led to design iterations. 

The camera needed a design concept which would allow it to leave the physical barrier of the payload, so that it could take photos of the payload and Earth. The initial design of the boom included a tape measure design, which would fold around the perimeter of the payload and snake out into an extended ~6 ft boom. Since then, the design has been edited to make the boom more robust and the camera more secure, and the tape measure design has been altered into a telescoping design (similar to an old phone or car radio antenna), due to limitations with manufacturing the prototype tape measure boom. 

The transmission system, which will send photos from the payload, once at apogee, to the ground system, also saw several iterations over the course of the project due to the fact it was the team’s first experience working with complex communication systems. The team initially considered using laser communication, sending the data of interest from the payload to ground using laser pulses. This idea was eventually abandoned, due to potential difficulty in obtaining approval to use high power laser pulses to communicate with an Earth station (in addition to the difficulty in designing such a system). Instead, the idea was replaced with an RF design, where a low power antenna design needed to be developed for the transmission side of the communication system. Eventually the team focused on designing a deploying dipole antenna design for the transmitter (which will deploy like an umbrella from the payload) to send images over radio frequency back to Earth from the onboard camera. This antenna design was chosen due to its flexibility with directionality and its low power consumption.