Stepping up to the cubesat bandwidth crunch
Posted on: February 4, 2019

Fast-growing fleets of very small satellites in low Earth orbit (LEO) are supporting a number of scientific research functions and helping scientists explore new space technologies that can be used on larger satellites. These “cubesats” (or nano-satellites), usually sized in multiples of 10×10×10 centimeters, are already assisting with Earth observation, global warming studies, amateur radio, and myriad other applications.[1]

Cubesats are also great for feasibility studies, remote sensing or communications, disaster response, climate monitoring, surveillance and reconnaissance, and offer endless possibilities for space-based scientific experiments.

No wonder NASA and others are running cubesat missions now, and planning more. Nearly 300 cubesats were launched in 2017, and over 700 launches are planned in 2023.[2]

Why the rush to nano-satellite technology? Launch costs, for one: it can cost up to $14,000 to launch a pound of gear into space.[3] So, smaller is better—but there are significant design challenges as well: cubesat electronics are smaller and are therefore more sensitive to radiation. Plus, not everything can be easily miniaturized, including all-important power supplies and communications technologies (a satellite isn’t much use if it can’t talk to other satellites or us Earthlings).

Since cubesats travel at low earth orbit, they only pass over their terrestrial signal-receiving points for a short time—as short as five minutes—during which they collect up to 360 Gbps of data (at best)—via the same radio frequency (RF) signaling technologies used to send us those grainy video images when Neil Armstrong first made that “giant leap for mankind” 50 years ago.

Considering the number of cubesat launches planned over the next five years, and the limited bandwidth provided by RF signaling and those short, five-minute communication windows, it’s easy to see there’ll be a serious bandwidth problem coming soon to a cubesat near you.

But also coming soon: free-space optical communications (i.e., light-based signals sent via laser) solutions ideally suited for high data-rate communications. Because light has a much higher frequency than RF/microwave, it can be modulated at a much higher frequency. (Microwave frequencies, such as those most commonly used in satellite and space communications, are in the range 1 GHz to 100 GHz, while light is around 200 THz.)

This higher frequency also means that light beam spread less than microwave beams, so a much greater portion of the signal will be captured by the receiver. Because light can transfer much more data per second, free-space optical communications are essential to meet the looming bandwidth crunch posed by fleets of cubesats.

At LGS Innovations, we’re helping NASA with laser amplification and targeting solutions to enable cubesats (and other satellites) to deliver proliferating volumes of imagery and data—and meet their mission.

Creating powerful free-space optical communications to drive our exploration of outer space is challenging. But that’s OK: At LGS, we like challenges. (And we’re hiring.)

[1] https://www.space.com/34324-cubesats.html (retrieved Nov. 6, 2018)

[2] https://en.wikipedia.org/wiki/CubeSat#/media/File:Nanosatellites_launched_by_years.png (ibid)

[3] https://science.howstuffworks.com/satellite10.htm (ibid)

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