Idea for EQUiSat 2.0: “Hall thruster powered by LiFePO4s – to go to the moon”
―Mckenna Cisler ’20, Brown Space Engineering
It began as a thought experiment for a class in 2011: “Developing a mission plan for a space related project.” On July 13, 2018 that plan became a reality when astronauts aboard the International Space Station (ISS) deployed EQUiSat. Undergraduate students from the Brown Space Engineering (BSE) team had designed and built a “cubesat” which NASA then launched on a cargo supply mission to the ISS in May of 2018. After deployment it started transmitting data from low-earth orbit to an antenna on the roof of Ladd Observatory and another ground station at Sapienza in Rome, Italy. In the words of former team member and class of ’14 astrophysicist Emily Gilbert: “***IT’S ALIVE! IT’S ALIVEEEEE!!!!***”
The idea for their mission was to test a new battery technology called lithium iron phosphate (LiFePO4) which had never flown in space. While all space missions are risky using untested components for an important scientific mission or in an expensive commercial satellite is an unacceptably high risk. The students set out to build an inexpensive testbed to prove this technology. The satellite cost $3,776.61 to build. That price tag doesn’t include the countless hours spent by more than 200 students to design and fabricate the parts of the satellite. NASA agreed to launch the satellite for free. If the results look promising it could lower the cost of future space missions and enable new capabilities.
But the technical requirements of the mission are merely a backdrop for a broader vision. The real goal and larger dream of BSE mechanical engineer Hunter Ray ’18 is “For space to become more affordable and accessible to a community other than astronauts and rocket scientists and to be able to look up at the Moon and see the lights of the first permanent extraplanetary settlement. ”
It is this enthusiasm that drives a project that could be described as a sort of “multigenerational” effort. It was started by one group of students who defined the mission and began the planning to accomplish the goal. Before they graduated they passed the project on to the next group of incoming students who designed and tested the prototype. This process continued for seven years until they completed the fabrication of the functional spacecraft named EQUiSat 1.0 which was delivered to NASA. During each year of the project one quarter of the team graduated and were replaced by incoming students.
The satellite is equipped with four LED strobe light arrays that are used to stress the battery. This process is sometimes referred to as “torture testing.” Solar panels charge the battery during the daylight half of the orbit and then the flash panel uses this stored power to discharge the battery during the nighttime half. This repeats for each 92.6 minute orbit. The satellite is 400 km (250 miles) above the surface of Earth. It orients the flash panel and antenna downward to face Providence by using a magnet to align with the Earth’s magnetic field.
The mission will continue collecting data into the fall 2018 semester. The mission will eventually end when the EQUiSat orbit decays to the point where it reenters the Earth’s atmosphere. It will literally burn out in a blaze of glory as it becomes an artificial meteor streaking through our sky.
For now it continues to “chirp” packets of computer data back to Earth. These chirps have been heard by ham radio operators around the world – similar to how Sputnik was tracked in the 1950s. Despite the ongoing mission the students have started to think about their next project. They are debating the mission objective of EQUiSat 2.0 which will be completed by students who have not yet applied for admission to Brown.
Team member Andrew Duncombe ’21 is currently studying computer engineering while also thinking about the possibility of equipping a cubesat with solar sail propulsion. Mckenna Cisler ’20 is using his experience with amateur radio to program the ground station to receive EQUiSat 1.0 data. He is also speculating about the feasibility of miniaturizing a Hall effect thruster to fit in a cubesat. Despite the fact that very few cubesats have been equipped with propulsion Mckenna is wondering how far it could propel a satellite. The technology to send such a small spacecraft to the Moon does not (yet) exist.