Surrey's SSTL-50 satellite bus
Two variants of Surrey Satellite Technology's SSTL-50 platform intended for satellites weighing 25-80 kilograms. Credit: SSTL

MOUNTAIN VIEW, Calif. — What’s the perfect size for a small satellite? “The answer is 42 kilograms,” said Martin Sweeting, Surrey Satellite Technology Ltd. founder and executive chairman said at the Small Satellite Symposium here.

Sweeting noted that 42 is also the answer the supercomputer in the science fiction series The Hitchhiker’s Guide to the Galaxy provides when asked the meaning of “life, the universe and everything.”

Sweeting said that a couple of years ago he worked with an Air Force Academy PhD student to create a formula to identify the optimal size for a satellite in terms of its cost, power and, most importantly, its utility. Satellites “round about” that 42-kilogram size have maximum utility, he said.

After years of celebrating the virtues of satellites smaller than a shoebox, many industry officials attending the Small Satellite Symposium Feb. 7 and 8 called for a shift toward slightly larger and more capable spacecraft.

That is not to say that cubesats are going away. The Indian Space Research Organisation plans to send 104 satellites into orbit on a PSLV rocket Feb. 15, including 88 imaging cubesats for Planet, one of many companies that use the miniature satellites for Earth observation.

But some missions simply don’t fit on cubesats.

“It is no longer the size of the puzzle that matters. It is the ability to know your pieces and bring them together to be economically viable for the mission at hand,” said Marco Villa, Tyvak Nanosatellite Systems president and chief operating officer. “The payload, mission and customer drive what you are doing.”

For synthetic aperture radar missions, cubesats are not the optimal size, said Dirk Wallinger, chairman and chief executive for York Space Systems, a Colorado startup planning to mass manufacture standard spacecraft buses.

York has contracts or letters of intent from customers seeking to buy 33 of its S-class three-axis stabilized satellites designed for payloads of 85 kilograms, Wallinger said. York is selling its basic S-class satellite for $675,000. Customers pay more to add payload flight computers, star trackers and other mission-related hardware.

Talbot Jaeger, NovaWurks founder and chief technologist, also is encouraging companies to look beyond cubesats. NovaWurks developed Hyper-Integrated Satlets or HISats, small autonomous satellitea that government and commercial customers can assemble in groups, like Legos, to support their payload.

While cubesats are inexpensive to launch, many of them do not survive long in orbit, Jaeger said. “Small satellites with long-lived, resilient architectures could produce missions that survive long enough to be profitable,” he said. “Either we drive the launch costs down or, at least in the near term, we take advantage of a more resilient capability with the price point that brings those missions into profitability.”

With greater resilience, commercial satellites of all sizes could take over some jobs currently performed by large government satellites, said David Anhalt, president of Blue Residuum, a Virginia startup that helps space entrepreneurs adopt commercial best practices.

No one thinks it will be easy to convince government customers who demand extensive testing and flight heritage parts to begin relying on commercial satellites that have not been built per government specifications. Nevertheless, government customers will turn to commercial satellites because they sell for a fraction of the price of government satellites and are built in a fraction of the time, Anhalt said.


Debra Werner is a correspondent for SpaceNews based in San Francisco. Debra earned a bachelor’s degree in communications from the University of California, Berkeley, and a master’s degree in Journalism from Northwestern University. She...