An interstellar journey

April 13, 2017 by Daniel McGlynn

Second-year engineering physics major Travis Brashears has a vision. He wants to build and launch a spacecraft capable of traveling 4.37 light years to our solar system’s nearest neighboring star system, Alpha Centauri. One of the challenges and there are many is the limitation of current rocket propulsion technology. It would take today’s most advanced spacecraft thousands of years to make the 25.6 trillion-mile trek.

As far as alternatives go, space technologists have proposed nuclear fusion and something called antimatter annihilation to speed the journey. Besides sounding perilous, these alternative ways of moving more efficiently through space are still pretty theoretical.

And, besides, those propulsion methods don’t really interest Brashears. Instead, he’s looking at an idea that is gaining traction within the space technology field that flips the traditional idea of spacecraft on its head. Rather than designing one big rocket or shuttle that carries fuel onboard, future space exploration might best be tasked to small craft that leave fuel behind. Instead of massive engines, energy from lasers would push small spaceships that are rigged with an energy-capturing, sail-like apparatus. Using transfer of momentum from the laser’s photons (which could be based on Earth or in space) creates the equivalent of trade winds for deep space.

The initial concept consists of nano-sized wafers equipped with communications gear and, after deploying, reflectors that unfurl to about a meter square sail, and launched every few minutes if needed to allow flotillas of thousands per year to improve the odds for success. As the technology develops, the spacecraft could scale in size in relation to the photon power of the laser deployed. The goal of using laser-powered nano craft, rather than traditional rockets laden with heavy fuel, is to reach rates of travel at 20 percent the speed of light, which makes interstellar travel at least comprehensible in terms of human lifetimes.

While this might sound far-fetched, using photon power to reach speed-of-light rates (in space terms, called relativistic flight) is very similar to the physics that propel particle beams at the European Organization for Nuclear Research’s (CERN) Large Hadron Collider.

That’s not to say that light-powered deep space exploration will be easy, or even possible anytime soon. “Did I forget to mention,” Brashears says after outlining his ambition, “This is not a trivial challenge. This is like a 50-year effort.” Despite the long view, Brashears is not interested in squandering his time.

That’s why he spent his first year on campus laying the groundwork for Space Technologies at California (STAC), a student group capable of furthering the vision of interstellar travel. Now, just months after its founding, STAC is already building an experimental payload filled with microgravity experiments that will launch in the fall on a rocket owned by the private space company Blue Origins. The payload experiments are just the first step; more ambitious plans include developing new tools and technologies, like a printed circuit board (PCB) satellite deployer to test prototypes of the wafer-sized craft.

Brashears is taking all of this on without losing sight of the big, big picture: “The main reason for founding this club,” he says, “is that we want to add to the understanding of space technologies.”

A roadmap to deep space

STAC is not Brashears’s first foray into space. As a junior in high school, he started working in a lab at UC Santa Barbara with physics professor Philip Lubin. “It’s kind of funny, because I was a researcher before I was a student,” Brashears says.

Lubin is known for his expertise on early universe studies and on directed energy and photonic propulsion in space applications, and he runs the experimental cosmology group, which is focused on a wide variety of astrophysics investigations. In addition to figuring out how to send small spacecraft beyond our solar system, Lubin also studies laser technology as a deep space communication tool (for possibly finding other intelligent life forms) and for other applications, such as asteroid mining and planetary defense.

“I have worked with more than 850 undergraduate researchers over my career,” Lubin says. “Travis was the most amazing high school student I had ever worked with and had the intuition and skills of someone far beyond his years. He understood intuitively what needed to be done both in the lab and in organizing a research program, and is now an integral part of our NASA Starlight program.”

Brashears returned to Lubin’s lab last summer, and the two continue collaborating on a variety of projects related to interstellar travel.

The main focus of their work has been laying out a roadmap to develop the technology necessary to make deep space exploration possible. The work is funded by a NASA Innovative Advanced Concepts (NIAC) grant, currently in a Phase II program, which allowed them to build a lab-based proof of concept for demonstrating the feasibility of laser-powered spacecraft. Brashears says, “We started landing all of these grants and things so we could work on it together.”

In addition to the interest from NASA, they have private funding from an anonymous donor, and about this time last year, billionaire media entrepreneur and investor Yuri Milner announced his Breakthrough Starshot, a $100 million research and development effort designed to support the development of laser propulsion technology.

Some of the world’s leading astrophysicists, including Stephen Hawking and Nobel prize-winning Berkeley professor Saul Perlmutter, sit on the Breakthrough Starshot advisory board, along with Lubin.

Building on his early collaborations, Brashears is adamant that successful space projects will require working across disciplines, departments and even campuses. So far, STAC continues to work with researchers from Lubin’s lab, and once ready, will test various prototypes at Berkeley’s Space Sciences Lab and UC Davis.


This is a prototype of STAC’s printed circuit board satellite deployer, which is an early step towards testing laser communication between small nodes in space. (Image courtesy STAC)Last September, Brashears met with electrical engineering and computer sciences (EECS) major Olivia Hsu to discuss forming a space-related organization on campus. Hsu had just spent the summer working on CubeSats (a standardized and modular satellite system that is rapidly becoming its own industry, with many commercial and research applications) at NASA’s Jet Propulsion Lab in Pasadena, California.

Together, they hatched a plan to get Berkeley students developing the tools needed for future space exploration. They envisioned STAC as a collaborative effort among UC campuses and research institutions, with lofty goals. “I think that STAC can definitely be one of the first student groups to build and launch CubeSats into space,” Hsu says.

The duo began recruiting other students. Like Philipp Wu, the team’s mechanical lead, who is double majoring in mechanical engineering and EECS and pursuing his interest in low-cost robotics research in the Berkeley Artificial Intelligence Lab.

And mechanical engineering major Varun Khurana, who leads the effort to build a CubeSat deployer for STAC. In its current iteration, the deployer is a spring-loaded system capable of flipping a quarter, which is roughly the size of the prototype PCB satellites.

EECS major Namrita Baru handles sponsorship and outreach for STAC and is working on getting her pilot’s license. She has been interested in planes and aerospace for as long as she can remember. Meanwhile, EECS and mechanical engineering major Abhishyant Khare is considering joining NASA’s Astronaut Corps. “Space poses so many interesting engineering and design challenges,” he says, “and to be able to work on that requires another level of ingenuity and problem-solving.”

STAC members are drawn to the opening of a new frontier and a sense of exploration that transcends borders and politics. No longer is space solely the domain of the military or government agencies. Instead, it’s increasingly the purview of innovative companies that are pushing the bounds of possibility.

“This is definitely becoming a passion of mine,” Hsu says. “Every kid dreams about being able to go into space or send something into space, and we are definitely making that a reality.”

Go for launch, building an experimental payload

infographic of STAC's microgravity experimental payloadA rendering of the components of STAC’s microgravity experiments payload. (Image courtesy STAC) Developing new technologies requires experimentation, but running experiments that mimic the vast emptiness of deep space is difficult. So last September, while Brashears attended a Dent: Space conference in San Francisco, he paid close attention when he heard about an opportunity that he thought would be a perfect fit for the newly formed STAC: a competition organized by the conference enabled the winner to design an experimental payload for a Blue Origin rocket test flight to be launched next fall.

Brashears and Hsu quickly developed a proposal for the payload, which can be no bigger than a cigar box, with a mass of 500 grams (roughly the equivalent of three iPhones). They sketched out four experiments that they thought could fit within the design constraints. Their proposal was accepted, winning a spot on the mission.

The experiments have to be carefully orchestrated to take advantage of the few minutes that the rocket will be in the microgravity conditions before returning to Earth. With the larger interstellar mission in mind, the STAC team’s payload is trying to understand some of the technologies needed for deep space travel.

“Each one of these experiments on board is moving forward an area of space research that hasn’t been tested before,” Brashears says.

Despite its compact size, STAC plans on launching the payload with “astronauts,” in this case millimeter-sized C.elegans, a species of transparent roundworms. “A bunch of biology professors work with C.elegans because they are a model organism for a lot of experiments and lifeforms,” Hsu says.

STAC’s experimental roundworms already have a space-related pedigree. The team is working with UC Santa Barbara biotechnology professor Joel Rothman, who maintains a group of C.elegans in suspended animation that are the descendants of the worms that were aboard the space shuttle Columbia, which exploded during re-entry on February 1, 2003.

The goal of the experiment is to attempt to reanimate the worms in microgravity conditions. “Once we get to microgravity, we have to heat the C. elegans to wake them up, but the process requires mixing water and glycerol, which is pretty intricate and doesn’t work so well in microgravity,” Brashears says. “So we’ll need some kind of mixing mechanism, which is very similar to what we’ll have to do in our first interstellar mission. So this is a really good precursor to that because we are trying to figure out how to wake these things up after being at -70 degrees Celsius.”

The team will also test laser technology for future asteroid mining applications. “It’s a 10-watt laser with a small lens that can focus on our synthetic asteroid sample,” Brashears says. ”Then we’ll watch to see if there is a difference in the ablation plume.”

“We all have something inside of us that is connected to space. I think that’s how we get people — we all have a desire to go to space.”

– Travis Brashears

A third experiment addresses a need for better understanding robotic design and functionality in space, where the laws of physics are different. “We can compare the data of what it will do on Earth, versus what it will do while accelerating upward, versus what it will do in a low-gravity situation, so we can better characterize how a future robotic arm would work in space,” says the team’s mechanical lead, Philipp Wu.

And finally, the team plans to test the communications capabilities of a PCB satellite being built at UC Santa Barbara, which is an early prototype for the still-to-come nano-sized wafer satellites.

“Staying within our mass budget is going to be pretty tricky,” Brashears says.

“And our power budget,” Hsu adds, “because they only give us about four-and-half watts, so we have to figure out how to distribute that so we can power everything.”

The students are pushing hard to have the payload prototype developed by the end of the semester. They’ll be dispersing for the summer for NASA internships, flying lessons and various space-related research opportunities. When they come back in the fall, they want to feel ready for launch.

They are also eager to bring various parts of their work together and show that Berkeley students are ready and willing to look out, well beyond the horizon.

“It’s definitely been hard to convince people that this is a thing,” Brashears says. “We all have something inside of us that is connected to space. I think that’s how we get people — we all have a desire to go to space.”