Tracking the Tiny Twinkles of Twilight
Suddenly, the skies glitter with dozens of new points of light. Not stars, but satellites, in quantities never before seen. On November 20, a Minotaur launch vehicle rocketed to the sky from the Mid-Atlantic Regional Spaceport in Virginia with a then record 29 satellites. Not to be outdone, a day later a Dnepr rocket launched from Dombarovsky, Russia carrying what then became the new record of 32 satellites. And seemingly to tell the world that that great mass of satellites wasn’t just some odd aberration of chance, just over two weeks after that, a ULA Altas V launched from Vandenberg Air Force Base in California with 13 more satellites in its payload bay.
I could go on by saying that, at the time of this article’s writing, another 33 satellites were waiting to be launched to the International Space Station (ISS) aboard an Orbital Sciences Corp Cygnus vehicle, but I think you’ll have gotten the point. There are a lot more satellites going up in rockets nowadays. Most readers of Thruster will also know that this isn’t a phenomenon of launch vehicles getting bigger but small satellites (“SmallSats”) becoming much more popular nowadays. (Please see “SmallSat Review” in the November 2013 issue of Thruster.) The attraction of low cost satellites carrying the latest in modern miniaturized electronic sensing equipment has become too compelling for commercial entities, researchers, government agencies and educators alike. In particular, the CubeSat form factor, a compact modular standard based on a simple geometric shape has attracted a worldwide following including, amongst many NSG-tracked companies: NanoSatisfi, Planet Labs and Dauria Aerospace. Historically, the trend was slow to build, but the aforementioned launches this November, December, and January proclaim more than anything that the era of proliferating SmallSats is here.
CLYD provides ground stations to SmallSat operators.
While many will focus on what these SmallSats will do in the sky, less is discussed about the practical considerations for the operators of all these satellites. All satellites, whether big or small, ultimately communicate with the ground, either to transmit telemetry and data or to relay communications, and these satellites are no exception. The big satellites of the 1st Vertical operated by governments or the likes of Intelsat or SES often have the benefit of big budgets and specialized ground stations in strategically placed locations around the world. SmallSats, often built by universities or startups, have much less ability to be so expansive and require simpler or sometimes more “off-the shelf” solutions. (Please see “Above the Cloud” in the December 2012 issue of Thruster.) As the sub-vertical of SmallSat developers continues to expand, the question of how best to develop a ground solution will continue to raise questions.
The usual solution, especially by universities fulfilling their role of being educational, is to simply build your own station. (Please see “SmallSat Review” in the October 2013 issue of Thruster.) Given that ground stations are, at their essence, nothing more than radio receivers and recorders, this is not a bad solution for many. In fact, if you wanted a small satellite ground station without going to the trouble of wiring up your own radio equipment, a variety of SmallSat vendors will sell you one, including NSG 100s such as Clyde Space, ISIS and SpaceQuest. Easy as pie.
Except the station will only receive while your satellite is directly overhead, which may occur for at most several minutes at a time with gaps of hours or days in between. Plus the data rate will be nothing to write home about. For some, this is not a problem, but for others it is a critical hurdle to overcome.
Another way is to rely on a larger network of multiple ground stations to manage your satellite. Such a thing exists – most notably there is Universal Space Network (USN), owned by the Swedish Space Company, which provides a global network of ground stations available for renting for whatever your satellite needs. Established in 1996, it counts as customers many LEO and GEO satellite operators as well as the U.S. Air Force and various space agencies. Ground stations are positioned around the world in places like Hawaii, Alaska, Sweden, Mauritius and Australia. Operators wanting more frequent downlinking opportunities can seek their network and services.
USN does its job well, but in an era of low cost distributed hardware and ubiquitous virtual global communications networks there is room for newer platforms. One such option is the Global Educational Network for Satellite Operations (GENSO), which is backed by a worldwide community of universities and has at least 14 ground stations in its network. As the number of satellites in orbit and their data demands expand, it’s a good bet we’ll see networks like this expand to meet the needs of their operators.
But what if you wanted continuous, no-interruption communication with your SmallSat? You would either need a very dense network of ground stations (including some floating in the middle of the Pacific!) or something else for communications. That something else could include using existing space infrastructure like communications satellites. The Iridium network is ideally suited for 24×7 communications although the Inmarsat system is also good, provided that the SmallSat is not polar orbiting. Though meant primarily for ships at sea, aircraft in flight and travelers in remote locations, there is no major reason that LEO satellites could not also use these networks. Therein one could access a global relay system with little more to build out. The major drawback, however, could be the ongoing cost and the limited data rates.
Universal Space Network provides a global network of ground stations.
Data rate could ultimately be the Achilles heel of SmallSats. With only so much link budget to be squeezed out of relatively small antennas, there are some limitations. Basic imaging satellites can perhaps manage the data rates, but what about advanced hyperspectral or atmospheric sensors that generate gigabytes of data a day at least? Modern electronics find it no problem to store mountains of data in very compact devices, even in as small a package as a CubeSat, but timely delivery of that data over tenuous ground station connections may be difficult. (This is why NSG Analysts have speculated 1st Tier NSG 100 SkyBox announced its partnership with Cloudera in 2012.)
What if we went back to the past for a solution? Before spy satellites had digital cameras and CCDs, they took their photos on film and brought them back to Earth in a capsule for processing. In the case of modern small LEO satellites, they tend to deorbit quickly anyways and in an era of Big Data, it may just be easier to physically bring back the data from space. As some might say, never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway, or in this case, the bandwidth of a solid state memory drive hurtling to Earth in a fiery re-entry.
TVA’s REBR re-entry capsule
One in NSG OTB particular, Terminal Velocity Aerospace, is developing a re-entry capsule that could be used for this purpose. If and when they go into operation, they could give the concept of a ground station a whole new meaning.
Ultimately, more users of space mean more and better infrastructure to continue to improve the ability of small organizations, students and ordinary people to access the stars. Which means we’d better get used to future rocket launches setting new satellite deployment records and making the skies glitter with ever more little points of light. And possibly a few data-rich shooting stars…
Ian Fichtenbaum is a Vice President with Near Earth, LLC and a frequent contributor to Thruster.
Image courtesy of Shutterstock
