Free-Flying Robots in Space: How Real-Life Droids are Testing New Tech

April 23, 2024 • By Amy Thompson, Contributing Author

Five years ago, on a space station not so far away, a trio of cube-shaped robots embarked on a multi-year mission to help pave the way for future robots and autonomous systems in space. Much like the droids of the “Star Wars” universe, NASA’s free-flying robotic system, Astrobee, aims to assist astronauts on the International Space Station (ISSInternational Space Station) with tasks and test out new technologies in ways not possible on Earth.

From communicating with various computer systems to grappling spacecraft or identifying potential hazards such as leaks on spacecraft, robotic helpers will be an integral part of future space exploration. They can also assist with everyday tasks and maintenance, enabling crews to focus more on research. That’s the idea behind Astrobee, a small swarm of free-flying robots buzzing around the space station.

Seemingly straight out of the pages of science fiction, Bumble, Honey, and Queen have helped with more than 150 investigations, many of which are sponsored by the ISS National Laboratory®, to test various technologies in space that have direct applications for both future exploration efforts as well as industries here on Earth.

Since beginning operations on the space station in 2019, the Astrobee facility, operated out of NASA’s Ames Research Center in Silicon Valley, has logged more than 1,200 operational hours. “One of the Astrobees’ main jobs right now is to conduct research that supports scientists who want to do space-based research,” said Jonathan Barlow, lead engineer for the Astrobee facility at NASA Ames. “Researchers may not be able to design a whole robot or spacecraft from the ground up, so they can leverage this platform to conduct their research.”

In addition to more technical ISS National Lab-sponsored experiments like acoustic mapping or testing spacecraft rendezvous and docking capabilities, the ‘bees also do science, technology, engineering, and mathematics (STEM) education outreach as part of the Massachusetts Institute of Technology’s (MIT) Zero Robotics program.

According to Barlow, the space station is an ideal place to test how projects run using the Astrobees to inform robotics systems for future space stations and even NASA’s planned Gateway lunar space station, which may not be crewed year-round and will need autonomous systems to remain operational. “The Astrobees are testing technologies that could be implemented in future long-duration or deep space missions, where crew might not be available,” Barlow said.

These Are the Droids You’re Looking For

One of the iconic scenes in “Star Wars” shows Luke Skywalker onboard the Millennium Falcon, learning the intricacies of “the Force” from Jedi master Obi-Wan Kenobi. Luke battles a training droid that resembles a floating ball, zapping him with lasers as part of his training.

That orb inspired the design of Astrobee’s volleyball-sized predecessors, a trio of 18-sided polyhedral satellites called Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES).

“The inspiration for the SPHERES project was actually a remote from ‘Star Wars,’” said Barlow. “David Miller, an MIT professor, showed that clip to his senior design class and said, ‘I want you to build me this.’ And sure enough, that’s exactly what they did.”

According to Barlow, Miller’s graduate students received funding from the Defense Advanced Research Projects Agency (DARPA) to build three SPHERES robots that launched to the space station in 2006. SPHERES operated for more than 10 years, participating in nearly 600 experiments that tested concepts from autonomous formation flying to navigation, mapping, and more. In 2010, the SPHERES project transferred from MIT to NASA Ames, where its success led to the rise of the Astrobees.

Queen Bees and Wanna Bees

Queen, Honey, and Bumble, along with a set of other test Astrobee robots, were named by the team at NASA Ames. “We wanted something on theme that wasn’t too irreverent or crazy,” said Barlow.

He explained that the name “Astrobee” was decided through a top coder competition, but the Ames team named the individual robots. Following a brainstorming session, the team selected the names for the space-based robots and their ground-based counterparts, including Wanna Bee, Bee Sharp, and Killer Bee.

Powered by electric fans, the Astrobees utilize cameras and sensors to “see” how to navigate and conduct experiments. They also have arm attachments to hold objects or keep steady for tasks requiring stability. Barlow says when designing the Astrobees, the teams envisioned a robotic system that’s smart and versatile enough to handle simpler maintenance and monitoring chores, leaving astronauts free to tackle more complex work.

“SPHERES were more limited in what they could do because we always had to have a crew member present as part of the safety controls,” Barlow said. “When we were developing the Astrobees, we wanted to take advantage of advances in technology and make them more robot-like as opposed to SPHERES, which were more satellite-like and were not designed to really interact with crew or their environment.”

Running off carbon dioxide tanks and disposable alkaline battery packs, the SPHERES robots were not designed to assist astronauts in practical ways, and their unique shape proved difficult to sustain. When designing the Astrobees, Barlow said the team opted for a cube shape to facilitate its design and accommodate potential attachments to increase its capabilities.

“Just the design challenges alone, like having to create curved circuit boards and other necessary parts, was enough to warrant the new shape,” he said. “It takes a lot of extra work to manufacture the parts needed to operate SPHERES, and the new design allowed for more payload capacity both inside the robot and on its exterior.”

Flight of the Bumble Bee

On June 14, 2019, Bumble became the first Astrobee to fly under its own power in space. Canadian Space Agency astronaut David Saint-Jacques was on hand to manually move the blue cube around the space station’s Kibo module, which enabled Bumble to calibrate its navigation system and verify that it could not only locate its position within the space station but also navigate as expected.

“This was such a fun project to work on, and I still remember it to this day,” Saint-Jacques said. “As an astronaut living on station, we spend a lot of our time repairing things that are broken or doing experiments that can be incredibly technical, but this project was completely different and a lot of fun.”

Saint-Jacques and his crewmates commissioned Bumble and set up the robots’ “hive,” or docking port, on station. Located in the Kibo module, the specialized platform would enable the ‘bees to recharge themselves and provided a storage place when they were not in use.

“One of the cool things about this project was that we were able to interact directly with researchers on the ground,” said Saint-Jacques. “It was really memorable because you could tell this project meant a lot to them. We could hear cheering in the background when the robot flew for the first time.”

Following Bumble’s initial success, Honey and Queen arrived on station. Researchers can use one Astrobee or two—or, on rare occasions, all three. Barlow says that typically, only one or two ‘bees are used because there are only two charging ports for them, with the third robot acting as a backup. The Astrobees can be operated via ground controllers or work autonomously.

NASA astronaut Megan McArthur also worked with the robotic assistants during her tenure on station. “As a science fiction nerd, I love all of the ideas about how humans and robots will work together in space to do all of the things that we do,” she said. “I love the idea of one day in the future having little free-flying robots that can move around and do things like take pictures of something instead of me having to stop, secure all of my tools, and find the camera.”

See-ing Through Sound

In science fiction movies, characters often carry portable electronic scanning devices to detect anything from machine malfunctions to potential hazards. Astronauts on the space station are also tasked with periodically scanning onboard equipment to identify issues before they become major problems.

But what if there was a better way? Samarjit Das, chief scientist at global engineering firm Bosch, thinks his company has developed technology that can help free up one of the most valuable resources on station: crew time.

C-3PO, the iconic protocol droid from “Star Wars,” is known for being well-versed in more than six million forms of communication and his ability to communicate with equipment. Similarly, Das and his team hope that a specialized microphone array combined with machine learning software can decipher the language of various pieces of equipment used on the space station and by industries here on Earth.

“People from around the world speak different languages, so it makes sense that everything around us is also talking, just in its own language,” Das said. “Everyday items, such as your computer, your car, and HVAC systems, are constantly communicating through sound vibrations, frequencies, and even currents.”

Das and his team partnered with Astrobotic—a private aerospace company developing robotic spacecraft and technologies for use on the Moon and other planetary bodies—to build a cutting-edge smart microphone array called SoundSee. Attached to a free-flying system like Astrobee, SoundSee could diagnose anomalies in spacecraft. Soundsee could also be used for applications on Earth, like in the automotive industry or manufacturing.

As a bustling scientific laboratory in low Earth orbit(Abbreviation: LEO) The orbit around the Earth that extends up to an altitude of 2,000 km (1,200 miles) from Earth’s surface. The International Space Station’s orbit is in LEO, at an altitude of approximately 250 miles., the space station can be a noisy place. In an ISS National Lab-sponsored investigation, Das said the team was able to demonstrate its SoundSee technology works.

“We wanted to demonstrate that a floating robot could essentially act as an automated inspector, conducting autonomous acoustic surveys, freeing up the astronauts to do more meaningful work,” he said. “And we did.”

Das says that Bosch is working on refining its microphone array and artificial intelligence capabilities for commercial use. The company hopes to use the technology in many industries and work with NASA and the ISS National Lab to deploy it on future missions and platforms like commercial space stations, the planned Gateway lunar space station, and more.

Stay on Target

The iconic command to stay on target may have been uttered by a squadron of X-wing pilots trying to blow up the Death Star in “Star Wars,” but a team of researchers from MIT and the German Space Agency (DLR) are hoping the mantra could help them recover tumbling satellites in space. Operations to rendezvous with an object are hard to plan when you don’t know exactly how the object is moving. However, the research team found a potential solution, which they tested in an ISS National Lab-sponsored investigation.

“We’ve assembled a set of algorithms that figures out how the target is tumbling, and then along with our other tools that allow us to account for uncertainty, we can produce a plan to get us to the target, despite the tumble,” said Keenan Albee who led the Relative Operations for Autonomous Maneuvers (ROAM) project at MIT before earning his Ph.D. and accepting a role in robotics at NASA’s Jet Propulsion Laboratory in California.

The team identified a set of algorithms they wanted to test in microgravityThe condition of perceived weightlessness created when an object is in free fall, for example when an object is in orbital motion. Microgravity alters many observable phenomena within the physical and life sciences, allowing scientists to study things in ways not possible on Earth. The International Space Station provides access to a persistent microgravity environment., focusing on simultaneous localization and mapping (SLAM), system identification, and predictive control. The project required two Astrobees—one acting as the tumbling target and the other acting as a chaser trying to rendezvous with the target.

Data collected from the Astrobees’ onboard cameras and sensors helped the chaser ‘bee model the target ‘bee’s motion and inertial properties. Using this data with the team’s algorithms, the chaser ‘bee identified a fixed point on the target ‘bee’s frame, resulting in a successful rendezvous in orbit. The ability to see the code operate in real time and refine the algorithms between runs was invaluable and resulted in multiple successful rendezvous maneuvers with different tumbling patterns.

Following ROAM’s success, Albee and the MIT team launched another Astrobee project, called RElative Satellites sWArming and Robotic Maneuvering (ReSWARM), to evaluate how well specific algorithms are able to control multiple satellites and perform in-orbit assembly maneuvers.

These projects not only allowed the researchers to advance their software but also provided enhancements to the Astrobee system. Portions of the data collected from the two investigations helped improve Astrobee’s localization system, which is used to identify where the robot is, and the flight code software. These updates will help future Astrobee users.

Inspiring the Next Generation

One of the legacies of the SPHERES project is its educational outreach. In 2009, the MIT Space Systems Lab created the Zero Robotics program. Modeled after the successful First Robotics program in schools across the country, Zero Robotics focuses more on software rather than building hardware, encouraging students to create code for competitions using the SPHERES robots on station.

For the first space-based competition, the challenge was to complete a task with the SPHERES robot before your opponent. The competition was a success, with more than 200 students from 19 states participating.

Danielle Wood, a professor at MIT, currently runs the program. “We call it ‘Zero Robotics’ for a reason: It’s in ‘zero gravity,’ there’s zero cost, and there’s zero configuration,” she said. “This means the teams don’t have to set up and configure the robots.”

When the SPHERES gave way to the Astrobees, the MIT team knew they had to keep Zero Robotics going. The program now holds competitions annually, with one in the summer targeting middle schoolers and another in the fall focused on high schoolers. Through these competitions, students use code to complete a different challenge every year.

“Students have the opportunity to design code and have it tested using Astrobee robots on the space station,” said Barlow. “They earn points, compete with other teams, and learn valuable skills to help them in the future.”

Wood says the number of students participating has increased over the years. “We had 600 students participating in 2023, and we keep trying to grow up to the next level year to year,” she said. “We’re really proud of what we’re achieving with this program and the students we’re reaching.”

As an ISS National Lab Space Station Explorers partner program, Zero Robotics significantly impacts students. By providing real-world experience both with the robots and the crew members on station, the program hopes to inspire students to pursue careers in STEM fields.

“I think when you find something that’s interesting for children, you can show them how it’s relevant to real research and the way we live and work in space,” said McArthur. “I think that’s really important for kids of all ages and from all walks of life. If they can see themselves doing something or find something that’s meaningful to them personally, it makes a connection that can inspire them.”

Benefits a Buzz

Droids are ubiquitous in the “Star Wars” universe, with nearly every household and spacecraft having at least one, but robotic helpers on the space station are just getting started. Thanks in part to their autonomous nature, the Astrobees are demonstrating they have the potential to be the robotic assistants NASA is looking for.

The Astrobee facility is a lower-cost technology test bed that allows researchers and students to test software and sensors through ISS National Lab-sponsored investigations. The facility’s increased capabilities have allowed it to far surpass its predecessor.

“We can run similar experiments to what we ran on the SPHERES, but the Astrobees’ enhanced capabilities have enabled so many additional investigations,” said Barlow. “The Astrobee facility has allowed us to essentially double the number of experiments we can do using robotic assistants.”

Robots will play a significant role in the future of space exploration, whether on the space station, future commercial space stations in low Earth orbit, NASA’s planned lunar space station, or missions to deep space. The Astrobees and other robotic helpers could serve as caretakers for destinations in low Earth orbit and beyond, as not every outpost will always be crewed. Through investigations such as those sponsored by the ISS National Lab, the team behind the Astrobee facility hopes to show everyone just how valuable these little space robots can be.