Tag Archive for: LEO

Optical Ground Stations, use laser light to encode data and transmit it back and forth between satellites in orbit and the network on the ground.

The story of optical satellite communications is a tale of the search for more bandwidth. Physics defines the terrain of the search — communicating across vast distances of space can only be accomplished using the electromagnetic spectrum, or EMS, where the higher the frequency (and the shorter the wavelength), the more data is encodable in the waveform. From S-band through C-band, to X-band and K-band, radio frequency, or RF, satellite communications have evolved from low-frequency dial-up speeds to today’s multi-gigabit per second very high throughput satellites using wavelengths under one centimeter.

But the highest frequencies of all in the electromagnetic spectrum are in the visible light end of the spectrum, up to 10,000 times higher than even the highest frequency Ka-band RF. The technology has existed to encode data in visible light since the development of fiber optic communications in the ‘70s and ‘80s. By that time, lasers were already a mature technology, used in consumer electronic devices like laserdisc or CD players.

The use of lasers to communicate data from satellites — sometimes called free-space optical communications, or FSOC, — has been a theoretical possibility for more than 40 years. The Japan Aerospace Exploration Agency demonstrated the technology in 1995, successfully achieving 1 megabit per second data download speeds from its engineering test satellite KIKU-6 to a ground station in Tokyo.

Today, a dozen or so companies, from startups to aerospace giants and major defense contractors are developing and selling free space optical technology, either to communicate with ground stations or between satellites in orbit or other spacecraft, with speeds up to 100 gigabits a second. Several test or demonstration projects are launching this year and if they are successful, the next two to four years could finally see the start of broad-scale deployment of FSOC technology in military and commercial constellations.

Iceye and Satlantis announced preliminary plans on Sept 14th to work with each other, to launch a constellation of four satellites to acquire high-resolution radar and optical imagery.

Satellites in the proposed Tandem4EO constellation would fly in formation in sun synchronous low-Earth orbit with two Iceye synthetic aperture radar satellites flying in a bistatic formation ahead of two Satlantis satellites designed to gather imagery with a resolution of less than one meter per pixel.

“Earth observation is ultimately about truly understanding what is happening in a selected location — with confidence,” Rafal Modrzewski, Iceye CEO and co-founder, said in a statement. “To achieve robust and fast analysis, combining the strengths of optical and SAR satellites in a single constellation yields incredibly useful insights for stakeholders in Spain and Europe.”

The Tandem4EO program is designed to bolster Spain’s New Space sector. Work would be performed at Finland-based Iceye’s manufacturing and research facilities in Jumilla, Spain, and Satlantis’ headquarters in Bilbao.

“Both companies will continue to increase their investments in their local operations, supporting Earth observation downstream applications in the European Union, and the growth of the local New Space ecosystem,” according to a Sept. 14 news release.

“Spain is in a remarkable position in Europe, with two leading New Space companies established in its territory opening new and unique opportunities in Earth observation,” Satlantis CEO Juan Tomás Hernani said in a statement. “This proposed initiative is the type of aerospace collaboration that would not have been feasible before. We’re in the golden age of New Space, and now is the right time to act on it.”

Flying radar satellites in a bistatic formation would allow Iceye to offer customers satellite interferometry, a product that can reveal millimeter-scale vertical differences in the Earth’s surface or structures. In addition, the combination of high-resolution optical imagery with SAR has applications related to natural catastrophes, security, environmental monitoring and infrastructure development, according to the news release.

Space sensors are DoD’s multi orbit plan for new constellations of missile-warning and missile-tracking satellites. But there is yet no consensus around a plan for how the Pentagon will transition from current legacy satellites to a much more distributed architecture of satellites in multiple orbits, argues a new report by the Aerospace Corp.

The report, “Fiscal Year 2023 U.S. Space Force Budget Request: Missile Warning & Tracking Looms Large,” was released Sept. 20 by the Aerospace Center for Space Policy and Strategy. 

About $4.7 billion of the Space Force’s $24.7 billion budget request for 2023 is for new this space sensors project which includes missile-defense satellites that the Pentagon argues is needed to detect and track advanced hypersonic missile and glide vehicles developed by Russia and China.  

“Over the next few years, the missile warning and tracking programs will weigh heavily in debates about the future of U.S. space systems,” said Sam Wilson, senior policy analyst at Aerospace and author of the report. 

The Space Force budget projections lay out a future architecture of about 135 low Earth orbit (LEO) satellites and 16 medium Earth orbit (MEO) satellites that would work in concert through an integrated ground system. 

The 2023 budget “funds efforts across all orbits, with the bulk of the funding being in geosynchronous Earth orbit (GEO) and polar,” Wilson wrote. These include the Next-Generation Overhead Persistent Infrared (Next-Gen OPIR) program with five satellites — three in GEO and two polar satellites.

This budget “ushers in a new approach for missile warning and missile tracking,” said Wilson.  Given their size and the number of stakeholders reliant on these programs, he noted, Congress could raise questions about how these complex programs are being orchestrated. 

“Although Congress seems supportive of moving to LEO and MEO, there seems to be a lack of consensus on how quickly, and in what manner, DoD should transition to this new architecture,” Wilson noted. 

Senate appropriators seem to want to accelerate this transition, he pointed out, cutting some of the funding for next-generation GEO and polar-orbiting systems and nearly doubling the funding for LEO and MEO. 

The multi-orbit approach, the report said, “may also be a harbinger for broader emphasis within the Pentagon to develop resilient and defendable architectures for other critical space missions. Such emphasis, if it materializes into more expensive and ambitious programs, could present significant budgetary pressures that DoD will need to balance, which could trigger additional scrutiny and concern from Congress.”

Deconflicting missile-defense projects has been a congressional priority amid concerns that agencies are developing systems in isolation and not coordinating efforts. Last week the Space Systems Command, the Space Development Agency and the Missile Defense Agency announced they formed a new program office to synchronize satellite procurements.

SDA is requesting proposals for a demonstration of laser communications between orbiting satellites and aircraft in flight.

As it prepares to start deploying a mesh network in low Earth orbit, the Space Development Agenc (SDA) is looking out for proposals for a demonstration of laser communications between orbiting satellites and aircraft in flight.

Last month, the agency issued a “special notice” asking vendors to submit by Sept. 2 proposals on how they would conduct a live demonstration of laser crosslinks between SDA’s Transport Layer satellites and a moving aircraft.

An SDA-funded experiment to test out this technology was launched in June 2021 but was unsuccessful. General Atomics Electromagnetic Systems launched two cubesats carrying optical communications terminals to test inter-satellite links but the cubesats never reached their intended orbit and the company was unable to establish contact. One of the goals of the experiment was to establish optical communications between the satellites and an optical terminal on a General Atomics unmanned aircraft. 

In the new solicitation, SDA asks vendors to figure out a way to connect one or more of the 20 Tranche 0 Transport Layer satellites — projected to launch in September — with an aircraft that would be chosen by the vendor. 

SDA is interested in a live flight demonstration but also would consider a phased experiment, starting with space to ground, space to a moving ground vehicle, and space to an airborne platform.

“This demonstration is concentrated on space to airborne test only to research, design, develop and test,” said the solicitation. “Testing must include successful demonstration of pointing, acquisition and tracking, and the capability to acquire and maintain the link with stability to pass up to 1 gigabit per second test data.”

Experts say optical communications between air and space is a tough technical challenge due to the difficulties of pointing and navigating while maintaining a link to a moving aircraft. It also requires correcting the turbulence in the atmosphere that interferes with lasers.