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Photonics is rapidly transforming into an enabling space technology with potential to cross-fertilize multiple markets in the space domain. Among them: navigation, remote sensing and telecommunications, as well as ground-breaking scientific and planetary exploration missions.
Because of advantages related to bandwidth, mass, power consumption, beam size and immunity to electromagnetic interference, photonic subsystems are now being considered in navigation satellite systems, Earth observation satellites, low Earth orbit (LEO) constellations and within telecom satellite payloads.
Satellites orbiting our planet usually do so within or close to the inner and outer Van Allen belts when they are deployed in the low Earth and geostationary orbits, respectively. Within these areas, because of the Earth’s magnetic field, transit galactic and solar cosmic radiation is trapped. The radiation consists of electrons, protons and heavier ions. Depending on the orbit in which the satellite is deployed, different types of radiation are present; hence different degradation mechanisms are activated. To make conditions more challenging, the effect of this orbit-dependent radiation differs according to the component characteristics, e.g., its material system and feature size.
Nonionizing radiation can be detrimental to optoelectronic components, as displacement damage is introduced within the lattice structure. If defects are introduced, they can lead to nonradiative recombination, reducing the efficiency of the device. In laser diodes, the degradation displacement damage is usually manifested as a threshold current shift. In photodetectors, the degradation is typically expressed as a drop of the responsivity — the amount of electrical current generated by a given incident number of photons.
Making space technology cheaper
MicroGic Electronics, founded single-handedly by CEO Yoram Malka, aims to change that perspective by implementing a NewSpace mindset – making space technology cheaper. It designs sophisticated cameras and sensors that allow ground teams to see what happens to satellites in space in real-time.
“We want to make space more accessible to people, ” Malka explained to CTech in an interview. “We want to bring space to more people, and change this concept that space technologies take a long time to build and launch, and cost a lot of money. We want people to know that more can be done with smaller budgets.”
“A decade ago, equipment used by the space industry cost between $100 million – $300 million, but with the NewSpace trend those prices are going down. We want everyone to be able to get to space. We’re bringing space to people.”
One of its biggest projects included the BGU satellite, built by Ben-Gurion University of the Negev and Israel Aerospace Industries, featuring MicroGic’s camera onboard to monitor mishaps that may transpire in space. The research satellite was designed to explore atmospheric and weather phenomena in the infrared wavelength, such as atmospheric gaseous contents.
For another project MicroGic worked with NSL Comm, designing small 14 megapixel cameras for the nanosatellites whose shoebox-size allows them to later deploy their large pop-up dishes in space, cutting down on weight, size and cost. “When those nano-antennas open in space, they need to be constantly photographed to monitor their conditions, or whether there is some sort of malfunction, and ensure that they are working accordingly,” Malka said. “It also helps us better understand whether or not we need to move around some parts so that a proper satellite transmission can go through.”
“It’s similar to how people take selfies on their cell phones,” explained Malka. “When you send an item to space, it needs to be monitored – whether that’s the sensors, the current, electrical voltage, or temperature, since you can’t see what’s happening up there. Our selfie camera can keep track of whether something gets damaged mid-use.”
But creating such a technology is far harder than it sounds. “Cameras in space need to deal with a variety of temperature fluctuations between -250 C (482 F) and 250 C (482 F). Nothing can survive those conditions, so we placed a stick with a mirror that extends from the satellite and can photograph the area behind the satellite.”
As to making its products more cost-effective, he added that the company doesn’t utilize any specific unique material, which could be expensive. “We design our lenses to withstand a variety of temperatures, and have found cheaper material capable of protecting those lenses in space’s harsh environment. Our cameras are smart cameras; they’re constantly thinking ten steps ahead, and can shut down when they encounter a harsh temperature within milliseconds.” This is thanks to the automotive industry, which has been designing cars’ electronics to be adaptable to different environments. “This helps the space tech industry obtain components that we couldn’t get back in the day.”
Performance evaluation
The photonic components deployed in space require additional performance evaluation when compared to conventional terrestrial telecommunication counterparts. The key parameter to be defined is the end-of-life performance when subjected to worst-case degradation factors. In certain cases, Telcordia-qualified components can be designed into a system with additional customization, further space assessment and up-screening. In other cases, a completely new design of the component is required because of the inherent limitation of the materials used or the manufacturing methods of the equivalent conventional terrestrial components. Most importantly, however, the components, modules and corresponding systems need to be able to operate under the presence of radiation. The Earth’s orbit is an inhospitable environment for electronics and photonics.
As such, a key milestone within the development phase of any space photonic hardware is the quantification of the performance degradation against the different types of radiation; this calculates the end-of-life performance to be used in the system worst-case analysis.
References and Resources also include:
https://www.photonics.com/Articles/Space_Photonics_A_Platform_Technology_for/a62298
