Undergraduate EXACT project aimed improving space navigation

Undergraduate Students at the Small Satellite Research Laboratory working on the Experiment for X-ray Navigation, Characterization and Timing (EXACT) underwent a review and site visit by the Air Force Research Laboratory at the end of 2024. The group passed their review with flying colors according to School of Physics and Astronomy Professor, Lindsay Glesener, faculty advisor to the Laboratory. The review covered the design phase of the project and means that the group can move forward with the testing phase of their design. 

Navigating your way on Earth is as simple as using a smartphone with GPS capabilities, but how do we figure out the location of a person or object in space? 

Currently, spacecraft and satellites near Earth use GPS, similar to how phones and cars navigate. However, GPS does not work in deep space. Instead, spacecraft rely on a system of large antennas on Earth called the Deep Space Network (DSN). The DSN has been supporting space missions since the Apollo era. As more spacecraft travel into deep space, the demand for the DSN is increasing, and it may eventually be unable to support all missions. Because of this, researchers are working on new methods for deep-space navigation. 

Students from the University of Minnesota's Small Satellite Research Lab (SSRL) are working on a solution by developing a sensor that uses signals from a type of star called a pulsar. Pulsars emit X-ray beams in a very regular pattern, similar to how lighthouses shine beams of light. The SSRL team aims to use these pulsars as natural navigation markers, similar to a GPS system, to help spacecraft determine their location in space.

The idea of using pulsars for navigation is not new, and this technology has been tested out before. For example, NASA’s NICER mission successfully demonstrated the use of a pulsar to navigate in space. NICER, however, is a large system (about the size of a washing machine or refrigerator) and would not be suitable for small satellites. For the past six years, the SSRL team has been focusing on advancing pulsar navigation by creating a much smaller pulsar navigation sensor that will still be able to get a strong lock on a position, impacting future endeavors into space.

“When we are sending out probes and [space] ships carrying people out to the Moon, Mars, or asteroid belt, we are going to need better solutions for navigation. I like to think that what our team is working on will ultimately become the main way humans navigate through the cosmos on interplanetary, deep space, and interstellar missions,” said Simeon Shaffar, senior in the AEM department and one of the chief engineers on the team. 

The project includes two “sister” space experiments, EXACT and IMPRESS. Both projects will fly the same payload in space, an X-ray spectrometer designed by a collaboration of Professor Lindsay Glesener from the School of Physics and Astronomy and the Montana State University (MSU). The X-ray spectrometer flown by the EXACT and IMPRESS experiments are identical in construction but will be used for two different missions. For the IMPRESS experiment, it will be used to look at the Sun and help answer fundamental questions about the dynamics of solar flares. In the case of EXACT, the payload will be used for deep space navigation. Students from across the College of Science and Engineering have been working hands-on developing both satellites. 

“The interdisciplinary aspect of this project is really cool. We have people involved from computer science, physics, aerospace engineering, and more. They all bring different skills that you need for this project. With EXACT, we are showing that there can be a simple and cost effective model that can be implemented into a full navigation system for future space missions,” said Kelsey Henry, senior in the physics department and a test engineer on the team. 

Projects like these are made possible through grants from the National Science Foundation (NSF) and the United States Air Force Research Lab (AFRL) University Nanosatellite Program, which provides funding to university students and programs to design, build, launch, and operate small satellites. 

From the beginning, the team spent time researching and obtaining commercialized parts for the project including radios, batteries, and GPS. Members of the SSRL team created the circuit boards, software, and overall structure of the system from scratch. The components needed to be carefully built and tested so that they would function properly once put together, creating a system larger than the sum of its parts. 

Mel Nightingale, a second year PhD student in the Department of Aerospace Engineering and Mechanics, first got involved in the program through a PSEO opportunity in high school. Mel has remained involved in the program throughout their higher education career and has experienced the importance of these programs first-hand. 

“You can’t really get this kind of experience anywhere else. Even with internships I’ve seen, you’re usually working on one small aspect of a project and the turn around is so long for missions that you might not even see it through in your internship time, so it really is a unique experience for undergraduates.” 

The team recently passed their program review with their AFRL sponsors on November 22nd and 23rd, 2025, an accomplishment highlighting the countless hours of work the students put into the project. The two day long program included a hardware, systems and mission review followed by a demonstration of the system using a prototype of EXACT, ensuring that all the electrical parts were working and connected in a flight-ready state.

The team is especially proud of the software they developed, a challenging component of the project that had initially fallen short at their last major review in 2023. Using the feedback they received, members of the SSRL team were able to completely rebuild the software almost entirely from scratch within a year and a half, greatly exceeding the expectations of their reviewers.

The project has given students the valuable opportunity of working hands-on while testing their ability to work with deadlines, time constraints, and each other.

“What these projects give students in terms of experience is invaluable. The science we're doing is interesting and important, and these programs also give students like us the opportunity to work on a project of this scale. It’s super helpful when applying for jobs, because now I have the experience of the research and development work similar to what is being done professionally. You can’t put a price tag on that,” said Charles Hartman, senior in the computer science department and one of the project managers on the team. 

With their latest review completed, the next few months will be spent conforming the current design that the team has built to fit the host specifications. The final stretch for the students involved in the project will be building the flight model out and preparing for their next review in the fall, the culmination of an exciting journey for the SSRL team and all of those who played a role in the project. 

The following School of Physics and Astronomy members were involved the EXACT project and the site review: Will Honnold (Detector Team Lead), Sydney Leggio (IMPRESS Project Manager)
Kelsey Henry (former QA Team Lead, now EXACT Project Manager), William Setterberg (IMPRESS Project Scientist) Lestat Clemmer (Lab Manager), Jefferson Carpenter (pursuing UMN Physics PHD soon), Qianping Kuang (Former Detector Lead, Physics Graduated Spring 2024)