Mini satellites, maximum possibilities
Smaller satellites are bringing space closer to a wider audience, but are they ready to take on roles meant for larger satellites?
Covert organizations, geopolitical rivalries, astronomical (pardon the pun) budgets, technology nearly indistinguishable from magic: a clichéd view of space exploration, but not an inaccurate one. Starting with the world’s first artificial satellite, Sputnik I, through the intense rivalries of the Cold War, and even down to India’s IRNSS navigation platform, space has mostly been the exclusive domain of nation-states (or powerful corporations).
But all that’s changing now. In what’s a fitting corollary to today’s start-up-focused, agile-is-smart, small-is-beautiful world, satellites have shrunk, physically as well in terms of budget, and are now within the reach of start-ups and educational institutions. From Australia to Silicon Valley, or even here in India, there’s a new boom in space, one riding on the shoulders of low-cost, lightweight satellites.
Traditional satellites can weigh as much as a few tonnes (the GSAT-11, the largest satellite built by the Indian Space Research Organisation, or Isro, tips the scales at just under 6,000kg). At the other end of the spectrum is KalamSat, weighing a miniscule 64g, designed by Space Kidz India, which offers hands-on and technology training programmes for students. Of course, this would be a meaningless comparison without taking into account the difference in their capabilities. The GSAT-11 is a full-fledged communications satellite, while the KalamSat was a technology experiment and test-bed that carried a handful of sensors to collect data for future missions.
In general, satellites that weigh less than 500kg are deserving of the tag “small satellite". However, it’s the really light ones that have become popular. You will find several weight classes emerging over the years: microsatellites (10-100kg), nanosatellites (1-10kg), picosatellites (100g-1kg), and femtosatellites (under 100g). Awais Ahmed, founder and team lead of the Bengaluru-based Pixxel, which straddles the fields of machine learning and satellite imagery, describes this in layman’s terms, “Anything from a shoebox to a refrigerator."
Why the emphasis on size? Cost, for one. Traditional satellites, such as India’s GSAT and Cartosat series, are expensive. Cartosat 2E, launched in 2017, had a budget of ₹ 160 crore, while the cost for the GSAT-9 communications satellite mission eventually touched ₹ 450 crore. Now compare this with a 1kg CubeSat, which could cost as little as ₹ 2.5 crore.
“Over 60% of the budget for a satellite mission is the cost of launching it. Lower mass offers a cost advantage," explains Rifath Sharook, chief technical officer of space education company Space Kidz India and lead scientist for the KalamSat mission. Combine this with the remarkable advances made in electronics over the years, and we are finally at a juncture where lightweight, specialized satellites based on affordable, off-the-shelf hardware can be a viable alternative to their larger cousins.
Yes, there’s a vast gap in capabilities, and you wouldn’t expect a shoebox-size satellite to replace a multi-million-dollar machine, but what if you don’t need all that power? As the saying goes, why use a sledgehammer to crack a nut. Nick Allain, brand head for Spire Global, which bills itself as a “data company that uses satellites as the means of collecting this data", points out how small satellites are critical to their business model. “There is no way we could have offered the services we do at our price point with a traditional solution," says Allain.
Cost saving is just one reason for the popularity of small form factors. Equally important is their role in creating what Ahmed calls “responsive access to space". Significantly less time is needed to build one (anything from a week to a couple of months, versus a few years for a larger satellite), so it’s easy to launch upgraded versions every few months, or even put up a massive constellation for wider coverage within a very short span. This speeded-up development process also allows for a regular launch schedule, making planning for future missions a lot simpler.
Allain points out how Spire builds its satellites in batches of four-eight. “It’s an iterative process. You learn quickly what works." According to Allain, it’s now possible to build a satellite in a day, and even with testing, the process requires less than a week—something that would have been impossible a few years ago.
But the greatest impetus for small satellites has come from the way they cater to new applications. SpaceX has plans to launch 12,000 satellites as part of its Starlink broadband project. Meanwhile, Spire, which has 60 satellites in orbit, offers maritime and aviation tracking (for uses as diverse as supply chain management, data collection for investors, environmental compliance and emergency response) and even weather forecasting. On the other hand, Pixxel, which will launch three satellites next year (with plans for another 30 by 2020), promises near real-time imagery for crop monitoring and fighting illegal mining. Then there’s Australia’s Fleet Space Technologies, which offers a satellite gateway for internet-of-things sensors (which connects on-ground sensors to a satellite link) for use in remote areas in the mining, agriculture and maritime industry (Fleet is currently using Iridium satellite constellation, but is in the process of launching its own as well).
Many factors have come together at the right time to create what Allain describes as the “space-as-a-service" industry.
It’s also interesting how these small satellites have attracted young students. Sharook was part of the student team (he was in high school) that created KalamSat. The founders of Pixxel worked together on BITS Pilani Goa’s Project Apeiro, which used a balloon-launched satellite, while the founders of Spire met at the International Space University in France. Today, it would be hard to pick out a university that’s not working on its own small satellite programme. There’s also official recognition. Isro is offering free training to students from developing nations, while the Indian Technology Congress Association’s India@75: Students’ Satellites programme hopes to enable the launch of 75 student-built satellites by 2022.
While small satellites might be getting a lot of attention, they have some limitations. Usually launched in lower orbits, their lifetime is affected by orbital decay. It’s not much of an issue given the lower cost and the fast pace of development, the bigger issue is that of physical capacity. Battery backup constraints and the available space limit how powerful these small satellites can get. We’re a long way off from expecting small satellites to take over a full-fledged communications role or to provide very high-resolution imagery. But Sharook remains optimistic, given the pace of technological improvements. “Parts will become smaller, power requirements will come down," says Sharook. The future is bright.
What are CubeSats?
Back in 1999, when Jordi Puig-Suari of California Polytechnic State University and Bob Twiggs, now with Morehead State University, came up with the CubeSat as a low-cost design for universities, they could not have imagined it would one day become the de facto standard for small satellites. It was noticed by Nasa and the US department of defence, eventually catching the eye of the private sector. It wasn’t just the lower cost but also the faster development time, suitability for specialized missions and the many advantages of a well-developed ecosystem.
CubeSats were originally meant to be a 10x10x10cm cube, with a weight of 1kg (later expanded to 1.33kg). They are stackable, making it possible to launch larger satellites while sticking to the standard format (a CubeSat-3U is a CubeSat with 10x10x30cm dimensions).
The CubeSat specification defines requirements for essential equipment, such as the data bus (which allows equipment to “talk" to each other) and the deployment canisters (which launch CubeSats from rockets). A factor in CubeSats’ success is the emphasis on commercial off-the-shelf (COTS) equipment, spurring the creation of a CubeSat-specific industry. There are marketplaces (such as Cubesatshop.com) which let satellite makers browse catalogues of equipment. At the same time, makers are free to tinker with their CubeSat missions.
Over the next few years, expect CubeSats to become more popular. Nasa’s Insight mission to Mars includes a pair of 6U CubeSats for use as communications relays, in what is the first interplanetary use of these tiny satellites.