Sometime this year, Raichelle Aniceto ’16, SM ’17 and her labmates plan to send up a satellite payload that will shoot lasers at the Earth. If the beams hit the right spot, they could bring scientists one step closer to achieving rapid communication across deep space and providing internet via satellite network for communities that lack telecommunications infrastructure on the ground. This pioneering effort is an early attempt to transmit data from a satellite using optical communications—sending information encoded in light—rather than radio frequencies. While the concept is not a new one, doing it in space means navigating a web of intertwined variables and limitations, from the weight of the satellite to the clouds that would block the lasers and the harsh radiation of space. And that’s exactly why Aniceto likes it.
Now a first-year doctoral student of space systems engineering, Aniceto recalls arriving at MIT in search of a field that was “a touch of everything.” That’s just what she got when she joined associate professor Kerri Cahoy’s Space Telecommunications, Astronomy and Radiation (STAR) Lab in the Department of Aeronautics and Astronautics as an undergraduate research assistant.
As a freshman, Aniceto started out machining test parts for a CubeSat that was later launched by NASA. She was quick to volunteer for any new task and over the next few years branched out into other areas of satellite engineering. She learned how to model the space environment and perform environmental tests on satellite systems, and also helped design a CubeSat for a lunar mission. A growing passion for communication satellites became something of an internet-connectivity mission when Aniceto visited the Philippines, her parents’ home country. There she saw how internet access might help impoverished children who can’t attend school for logistical or financial reasons.
“If kids have internet,” she says, and therefore access to free online videos and courses, “it’s a way for them to be able to sit down and teach themselves.”
Opting to return to MIT after graduation to continue work with Cahoy (who now holds the Rockwell International Career Development Chair), Aniceto joined a team developing an experimental optical communications system for a CubeSat expected to launch this year. She is also doing optical communications research sponsored by Facebook Connectivity Lab, which aims to provide affordable global internet access through high-altitude drones.
Beaming information from a satellite to a receiver on Earth with a laser, as the STAR Lab’s system is designed to do, would allow for much greater data transfer rates than are possible with traditionally used radio frequencies. But with every benefit comes a tradeoff: the narrow beam is more secure, but needs to be pointed very precisely in order to hit a receiver on the ground. Lasers aren’t regulated the way radio frequencies are, but they have to be amplified to reach Earth and can’t penetrate clouds. On top of this, Aniceto’s optical communications system will need to fit inside a satellite about the size of a loaf of bread; it must be light and energy efficient and not generate too much heat, but also be able to withstand the vibration of launch and the radiation of space.
In this tangle of challenges, Aniceto is focused on understanding the effects of radiation on system components. Her goal is to design optical communication systems as inexpensively as possible by identifying commercial off-the-shelf parts that can withstand the expected radiation of a given mission. She says a system might use 50 or so electronic parts, and each qualified, radiation-resistant part might cost a few hundred dollars. So, she’s systematically testing cheaper alternatives. First, she runs a computer simulation of the mission in question to determine the expected types and amount of radiation the satellite will experience, then calibrates a radiation chamber to match those conditions and radiates the part. This work builds on her master’s research and places Aniceto at the intersection of the fields of optical communications and radiation effects.
“I haven’t really met people that are at the bridge of those two yet, besides myself,” she says. But she doesn’t seem to mind. “I love the puzzle,” she says with a smile.