Please tell us about yourself

In Sreeja Nag’s native India, people living in poor rural areas don’t lead the kind of energy-intensive lifestyles common in countries like America.

“The thin line between energy as a need vs. energy as a luxury is very subjective. It depends on what people are used to,” she said. What worries her is that the number of those living energy-rich lifestyles is increasing much faster than the rate at which technology is progressing to produce enough clean energy to meet future demand.

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Sponsored by MIT Energy Initiative (MITEI) sustaining member Total, a leading oil and gas company, Nag is one of 47 MIT Energy Fellows supported by MITEI member companies in 2009-2010. A first-year graduate student in the MIT Technology and Policy Program (TPP), Nag is working to conserve energy on the ground—and in outer space.

Working with the strategic engineering group led by Olivier L. de Weck, associate professor of aeronautics and astronautics and engineering systems, Nag is looking at the feasibility of replacing “monolithic” spacecraft with a mix-and-match cluster of smaller modules. By employing so-called fractionated spacecraft—free-flying units that work together to generate power, communicate, etc.—scientists hope to add flexibility and boost mission life spans.

Nag intends to apply this approach to a new energy- and environment-related Earth observation mission. While its exact focus is not yet determined, the mission would incorporate a series of satellites flying in formation and exchanging power and information wirelessly. This architecture, she believes, might be more economical and energy-efficient than existing systems.

Please tell us about your work

A team of small, shoebox-sized satellites, flying in formation around the Earth, could estimate the planet’s reflected energy with twice the accuracy of traditional monolith satellites, according to an MIT-led study published online in Acta Astronautica. If done right, such satellite swarms could also be cheaper to build, launch, and maintain.

The researchers, led by Sreeja Nag, simulated the performance of a single large, orbiting satellite with nine sensors, compared with a cluster of three to eight small, single-sensor satellites flying together around the Earth. In particular, the team looked at how each satellite formation measures albedo, or the amount of light reflected from the Earth — an indication of how much heat the planet reflects.

The team found that clusters of four or more small satellites were able to look at a single location on Earth from multiple angles, and measure that location’s total reflectance with an error that is half that of single satellites in operation today. Nag says such a correction in estimation error could significantly improve scientists’ climate projections.

How did you end up in such an offbeat, unconventional and interesting career?

Nag grew up in a quiet town called Pune, 100 miles from Mumbai. Cradled in a valley of the Western Ghats range, Pune is “a perfect distance from clean beaches and mystic mountains,” she said, adding that she is a bit regretful that it has been transformed into a big, crowded, traffic-filled city. She ended up attending college in a West Bengal village more than 35 hours by train from her hometown. Nag graduated in 2009 with bachelor’s and master’s degrees in exploration geophysics from the Indian Institute of Technology (IIT) in Kharagapur.

Once called an “academic maverick” with interests ranging from science and math to ethics and international policy, Nag took part in two very different and far-flung summer programs before graduating from the IIT. In summer 2007, she lived in a beach- and woods-bordered cottage in Woods Hole, Mass., as a summer fellow studying seismic tomography; and in summer 2008, she worked on the Fundamental Mars Exploration Project at NASA’s Jet Propulsion Laboratory on the West Coast.

She applied to many graduate programs but decided MIT’s mix of analytical and qualitative studies fit the bill. She is doing her PhD in Aerospace/Aeronautical Ástronautical engineering. In addition, she enjoys living in proximity to Boston’s high-powered academic institutions, museums, “cruises on the river, great walking and trekking spots and a zillion other creative events, seminars, talks and debates. One can wander and never feel lost,” she said.

How will your work benefit the community

In addition to her thesis research, Nag spent a month earlier this year helping to make solar power available to poor rural communities. During MIT’s inter-semester break in January, she worked with the Bangalore-based Solar Electric Light Company (SELCO), which has installed more than 100,000 solar lighting systems in homes and businesses in areas of India where many people survive on as little as $1 a day.

Nag hopes to address energy issues from as many angles as she can. “I find it very intriguing that we as human beings have the capability of optimizing or even manipulating energy systems using our own creative intelligence as well as programmed machine intelligence,” she said. In her own work, she incorporates both.