Low-Earth-Orbit Satellites and IoT: The Next Space Revolution
Over the past few decades, small satellites and IoT have dramatically changed the future of humans in space. The big money is now on business and space exploration has moved from one-of-a-kind systems performing specific missions to satellite constellations working in concert to achieve a larger purpose. Like the industrial revolution, when new manufacturing processes marked a historic turning point, low-Earth-orbit satellites (LEOs) are poised to transform our relationship with outer space.
While mass production of small satellites and IoT conjures up thoughts of large factories with assembly lines rolling out standardized products, it may not be that simple. High volume production would be necessary to achieve the global coverage sought by commercial and government stakeholders. In that business, new problems must be solved in quality control, standards, and in designing for manufacturability, as well as the challenges of automated assembly, integration, and testing – all of which must be balanced with cost considerations that are critical to the success of starting up. The development and launch of tens, hundreds, or even thousands of small satellites is starting to happen and it will almost certainly produce revolutionary effects.
The first low-Earth-orbit satellites were launched many decades ago. Those “birds” were owned and operated by national governments – at a huge cost to taxpayers. Despite the cost, over the past two or three years the LEO industry has been growing exponentially in the private sector, which raises the question of what is attracting this interest.
The major purpose of these groups of thousands of small satellites (constellations) is to have connectivity that gives 100 percent global coverage. The world is currently comprised of approximately four billion active Internet users, which means there are approximately 3.5 billion additional people who currently lack access. Once in orbit and fully operational, each new constellation brings total coverage closer but, at the same time, they will also provide 100 percent coverage in other domains – such as constant worldwide surveillance and imaging. Two definitions might help here:
- When it’s in a geosynchronous orbit (GSO), a satellite has an orbital period that matches the Earth’s axial rotation period of approximately 23 hours 56 minutes and 4 seconds (one “sidereal day”). Variously called a geostationary orbit, geostationary Earth orbit or geosynchronous equatorial orbit (GEO), the path taken forms a circle round the equator at around 35,786 kilometers above the equator and following the direction of the planet’s rotation.
- Low Earth orbit is classed as an altitude of 2,000 kilometers above the Earth’s surface, with an orbital period that stays between 84 minutes and 127 minutes. Any objects below a threshold of approximately 160 kilometers will experience very rapid orbital decay and altitude loss, so LEO satellites fly well above this danger zone.
Typically, all the privately owned and operated satellites have been launched into fxed positions on the GEO belt, keeping pace with the Earth’s rotation, and positioned at a very large distance from the Earth – much further out than the LEO belt. Because of this, each GEO satellite can cover larger areas of land mass and bodies of water. Some of the main limitations of GEOs, compared with LEOs, include these four critical factors:
- The GEO’s entire frequency spectrum is shared across the entire coverage area.
- Many of the GEO’s users are in a single satellite coverage area.
- Mobile antennas must point at a GEO satellite. As the mobile antenna moves further away in longitude from the orbital slot location (the skew angle) signal quality drops.
- There is no GEO coverage around the polar caps.
Thousands of smaller satellites and IoT are being launched into low orbit in order to have them work together and operate, effectively, as one unit or one system. Large constellations are required to achieve global coverage, especially given their location relative to Earth. Since LEOs are closer to Earth, they have the disadvantage of covering much less territory. This is due to the limited field of view from the antennas on board each spacecraft. Having been used over a longer period of time, there are many more GEO players. Among some of the main operators are: Intelsat, SES, Eutelsat, and Telesat. LEO satellites use a new, and growing, technology, and there are currently three major players: SpaceX, LeoSat, and OneWeb.
“SpaceX will build a network of 12,000 satellites as part of our Starlink project aimed at bringing ultra-high-speed Internet to the world,” SpaceX CEO Elon Musk said in November 2018. In the end, he plans to further digitize every industry in the world, one satellite data burst at a time, which told a technology story that many outside the satellite industry might have previously thought was irrelevant to them. In fact, to achieve even minor Internet coverage over the developed countries, Musk only needs 420 satellites. “That might be my lucky number,” he joked to journalists, referring to California’s State Senate bill leagalizing Marijunana.
Closer to Home: Unlike geosynchronous satellites, LEOs ﬂy as low as 2,000 kilometers and are thus able to pick up weaker signals.
However, this requires a network of thousands of satellites in order to provide global coverage.
SpaceX is certainly not the only player looking to accelerate and alter the universe of LEO satellites, and SpaceX is not the only major company positioning itself to deliver a whole new kind of service. Some relatively unknown firms have been formed and financed to grab hold of the opportunity. For example, a company known as LeoSat Enterprises was recently established to leverage the latest developments in satellite communications technologies.
Competing with SpaceX, its focus is to develop and launch a new LEO satellite constellation, providing what it claims will be “the first commercially available, business-grade, extremely high-speed, and secure data service worldwide.”
With up to 108 low-orbit communications satellites in the constellation, LeoSat wants to be the first to have all the high-throughput satellites (HTS) in the constellation interconnected through laser links. If successful, this approach will create an optical backbone in space – which would be 1.5 times faster than terrestrial fber backbones, and without the need for any earthbound touchpoints.
“SpaceX wants to bring ultrahigh-speed internet to the world.” Elon Musk, CEO of SpaceX
Based in Washington DC, LeoSat is currently working with the FrancoItalian aerospace firm Thales Alenia Space to establish the LEO network. LeoSat’s launch of its satellites is expected in 2020. Once operational, the constellation will provide high-speed, low-latency, and highly secure communications and bandwidth for business operations. The company’s focus is on three markets: telecom backhaul, energy, maritime, government, and international business.
Cut Off from Tomorrow: There are still enormous opportunities for service providers to connect the unconnected
and continue to expand their service offerings, INTELSAT believes. (Click for full size)
The biggest LEO advances are being made with small spacecraft and satellites. These are the “smallsats” which have been helping to advance scientific and human exploration, reduce the cost of new space missions, and expand access to space. Through technological innovation, smallsats enable entirely new architectures for a wide range of activities in space with the potential for exponential jumps in transformative science.
Some of the NATO members are contemplating alternatives to individual government-developed satellites for producing high-resolution imagery. The concept is for the US to commission proven and successful commercial satellites, with minimal nonrecurring engineering costs, to help augment current systems deployed by individual governments. The benefit of this proposal is to bolster the reliability and affordability of a system that is currently used in space, thereby reducing risk and production times significantly.
It is predicted that new constellations of extremely small commercial satellites, each with short life cycles that are reconstituted on a monthly or quarterly cycle, will invigorate the commercial satellite workforce and allow for more resilient production of future systems. The useful lifetime of GEO satellites averages about 15 years, a limit primarily imposed by the exhaustion of on-board propellants. These propellants are needed for “station-keeping” – maintaining the satellite in its orbital slot and orientation, or attitude, so that the satellite’s antennas and solar panels point in the right direction.
NASA gets Small
NASA has already played a big role in the smallsat revolution. For example, its Small Spacecraft Technology Program (SSTP) develops and demonstrates new small spacecraft technologies and capabilities for its missions in science, exploration, and space operations. SSTP promotes the small spacecraft approach as a major shift for NASA and the space community as a whole. As part of the project, NASA has launched a Smallsat Technology Partnerships initiative which represents a promising form of collaboration with universities in both technology development and demonstrations.
Shrinking Satellites: Small spacecraft and platforms are becoming more and more capable as their overall size continues to decrease.
Due to their size, they can share launch vehicles, which further reduces costs.
The development and implementation of multiple launches took place from 2017 through 2018 for three small spacecraft missions, sponsored and funded by the SSTP. These smallsats are demonstrating a number of technologies, including high-speed optical communications to increase downlink rates, and formation ﬂight and docking activities.
What exactly is a small spacecraft? The definition is arbitrary but NASA considers small spacecraft to be those with a mass of less than 180 kilograms. Other commonly accepted terms used for small spacecraft are the following:
- Minisatellite – 100 kg or higher
- Microsatellite – 10 kg to 100 kg
- Nanosatellite – 1kg to 10 kg
- Picosatellite – 10 g to 1 kg
- Femtosatellite – 1 g to 10 g
A cubesat is a special category of nanosatellite. One cubesat unit (1U) has dimensions of 10 cm × 10 cm × 11 cm but they have also been built in 1.5U, 2U, 3U, and 6U sizes.
"We’re only at the cusp of the Space Renaissance period we have now entered." Deborah Lee James, former Secretary of the US Air Force
Small spacecraft represent an emerging class of satellites, robots, and systems that exploit their small size to take advantage of sharing in single launch opportunities (ridesharing) at reduced cost. Small spacecraft also capitalize on the growing number of technical capabilities that are appearing in the high-technology and electronics industries. As a result, small spacecraft and platforms are becoming more and more capable as their overall size continues to decrease. Will government agencies like NASA stay involved? This is not just an academic question. Businesses who need the data from space – to understand current conditions on the ground, whether for agriculture, transport, or a dozen other industries – are nervously waiting to see what levels of commitment will come from their governments, since that helps to incentivize private funding.
Scientists, whether they be inside government, business, or academia, are bemoaning the lack of essential observations from space. This is currently a major limiting factor in many areas of research. Recent science and technology advances – in sensors and in spacecraft technologies – make it feasible to obtain key measurements from low-cost smallsat missions. One particularly promising aspect of this development is the prospect of obtaining multipoint observations in space that are critical for addressing many outstanding problems facing both business and science.
Space-based measurements from small satellites have great potential to advance discovery and to increase our collective understanding of what’s taking place on Earth. As a result, some national governments are ramping up their financial support of firms and universities that are working with small satellites to develop systems; construct, launch, and then operate them while in orbit; and, ultimately, to analyze the rich data.
In summary, great changes are taking off in the satellite industry. Small satellites are maturing to offer agility, affordability, resiliency, and high-resolution imagery. Simultaneously, government leaders are examining the potential threats posed by numerous military adversaries to space-based “legacy systems” already in orbit. Deborah Lee James, former Secretary of the US Air Force, recently shared some of her reﬂections and predictions. Calling the present a time of innovation and investor excitement, with the promise of new space exploration and new ways of doing business, she said, “We’re only just at the cusp of the Space Renaissance period we have now entered.”
Increasingly, the emerging LEO smallsat technologies are being looked upon as providing a complementary layer to the larger-scale systems – especially GEO satellites – providing a necessary new approach to ensure space-based capabilities continue to expand.
|This article was written for Smart Industry - The IoT Business Magazine.
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By Gordon Feller