Sounding Rocket Tech Enables Science Investigations

If you build a better sounding rocket science platform, scientists will beat a path to your payload bay.

Scientists from NASA and partner institutions have a new vehicle to collect multi-point measurements from Earth’s upper atmosphere. The so-called Swarm Communications technology ejects four to 16 science instrument packages from sounding rockets. These sub-payloads spread up to 25 miles while streaming telemetry and science data in real time through the host rocket’s communications system to the ground.

Sounding Rocket Program Technologist Cathy Hesh and Electrical Engineer Scott Hesh assembled a team of engineers to develop this technology in 2017 in response to requests from scientists in NASA’s Sounding Rocket Working group. Today, after four Internal Research and Development (IRAD) grants and three test flights, they can provide a science vehicle offering unprecedented accuracy for monitoring Earth’s atmosphere and solar weather.

“We were lucky enough that we had this core team with the right skill set to get this done,” Scott Hesh said. “We were able to turn this around from concept to flight in under three years.”

Starting with a vapor ejection system used to measure upper atmosphere winds, the team developed a standardized sensor platform and data collection architecture.

Mechanical engineer Josh Yacobucci said team members came together with a singular focus on this project.

“We knew from the beginning that we wanted one sub-payload that would be either spring- or rocket-ejected and not have to rely on separate designs for each option,” he said. “Every time we got together, diverse perspectives on the team led to improvements in different systems.”

Sub-payloads deployed with springs can carry larger payloads, but they eject from the rocket at 8 feet per second. This speed allows up to a 0.6-mile radius of separation from the main payload. Adding a small rocket motor limits space inside the cannister but increases their velocity by a factor of 48 for a 15-mile separation. They dubbed their project Swarm Communications, Scott Hesh said, because it communicates with a large number of sub-payloads, though individual cannisters do not operate independently as in other NASA swarm initiatives.

Sounding rockets are sub-orbital launches from locations like NASA’s Wallops Flight Facility near Chincoteague, Virginia. They provide a low-cost platform to test new space-bound technology and conduct science experiments that cannot be accomplished on the ground. Sounding rockets, along with balloons and aircraft, are part of NASA’s Affordable Access to Space program that brings these opportunities to scientists, educational institutions, and students.

So far, the swarm technology has been well received.

“This was an excellent mission,” Barjatya said. “Preliminary analysis shows that we flew through a Sporadic E event on the down leg and the data looks great. We’ll be looking at the performance of all instruments to get us ready for a 2024 launch.”

Riding on the third launch this August, researcher Dr. Aroh Barjatya’s Sporadic-E ElectroDynamics Demonstration mission, or SpEED Demon, traveled up to 100 miles altitude on a Terrier-Improved Malemute rocket. He sought to measure conditions of a transitory Sporadic E event: where a cloud of evaporated micrometeor metals can reflect radio signals at a level in the ionosphere that doesn’t normally reflect radio.

Barjatya directs the Space and Atmospheric Instrumentation Lab at Embry-Riddle Aeronautical University in Daytona Beach, Florida.

“There has been huge interest in our in our experimenter community to put their sensor packages on this platform,” Scott Hesh said. “It’s really not that hard for them to build these sub-payloads now that we have a platform with standard data interfaces and a standardized power supply. That takes a lot of design effort off them.”

“We can’t build the sub-payloads fast enough to keep our customers happy,” he added. “That’s a good problem to have.”

Working with scientists from the beginning allowed the team to direct their efforts to provide better science results, Cathy Hesh said.

“We ended up taking on several instruments and they got a lot of science data back even on our first test flight,” she said. “We also got good, real-time feedback from the scientists to help improve the whole project.” v

Engineer Scott Hesh credits the NASA Sounding Rocket Program for providing a fast and agile framework for engineering and innovation, providing scientists low-cost access to space and a fast turnaround, averaging 2-3 years to develop and fly a mission.

That cadence also provides an ideal environment for engineers to ‘lean forward smartly’ and improve on each new iteration.

Between each of the three swarm test flights, the Wallops team improved the quality and reliability of critical systems – communications, telemetry, and core electronics – as well as maximizing the volume of each sub-payload cannister set aside for science instruments.

One hurdle to collecting science data from distributed instruments is knowing precisely where and when each sensor collected each data point. Sounding rockets’ fast turnaround from concept to flight and the swarm team’s ability to advance the design for each flight solved this challenge.

Hesh’s first launch in 2019 used inertial sensors to provide acceleration, then calculated speed and direction over time for location plots. On the second launch, they added GPS (Global Positioning System) capability to each cannister; however, the system was unable to acquire a GPS lock in flight. For the third flight a year later, the team improved the GPS design based on lessons learned. The new version provided accurate time and position data to the science team with a small, cost-effective system.

Communicating to the ground is tricky with four sub-payloads and a rocket, and most launch facilities don’t have the antenna infrastructure to track that many payloads simultaneously, Hesh said. Instead, each sub-payload sends its data to the sounding rocket, where they combine into a single 6-megabit-per-second or higher stream that is transmitted to the ground, essentially providing five data sets in one. They can expand up to 40 megabits, he said, allowing a single rocket to eject and track 12 or more sub-payloads.

This, and a portable ground hardware rack, allows the system to be deployed from remote facilities around the world with fewer communication resources.

In ground control, that data is presented in a visual format that doesn’t overload the human technicians and scientists monitoring their measurements. Color-coded streams of data from each sub-payload allow a single person to scan for sensor anomalies as well as data on the sounding rocket’s telemetry and control systems.

The Swarm Communications technology has optimized the capacity of the cannister form factor, Hesh said. Making that into a truly distributed swarm mission would require expanding it to the next level.

He said he envisions leveraging more mature and larger-format CubeSat technology, “Then you could add reaction wheels to allow a stabilized platform, expand core flight software, test new CubeSat technologies, or even have the sub-payloads talk to each other,” Hesh said.