Toronto’s Space Flight Laboratory (SFL) and the Norwegian Space Agency (NOSA) say that they have successfully transferred data from a small CubeSat to a ground station using a laser-based optical link. This is a first for Dutch-built laser communications devices, and one of the few times that it’s been done on a small satellite and which posed a challenge with the various payloads.
The overall technology demonstration mission, called NorSat-TD, was led by NOSA, in cooperation with the French space agency CNES, the Netherlands Space Office, and the Italian Space Agency (ASI). The satellite was built by SFL, while the optical payload (the Small Communication Active Terminal or “SmallCAT”) was developed by a consortium led by the Netherlands Organization for Applied Scientific Research (TNO), with funding from the Dutch Space Office and the Dutch Ministry of Defense
SpaceQ contacted several people at NOSA, TNO, and SFL about the mission. They provided more details on NorSat-TD, and how they each contributed, via an email exchange.
SmallCAT Optical Communications
Optical communications use pulsed lasers in order to convey information, and are somewhat similar to the communications used in the terrestrial fiber optic cables that form the backbone of modern Internet communication. While they can carry a potentially enormous amount of information in a comparatively small laser signal, they’re also attractive to government and national security clients because they’re point-to-point, rendering them much less likely to be intercepted than more traditional radio-based satellite communications.
While they’re relatively common in larger satellites, this is one of the first times they’ve been deployed in a satellite this size. That presented several unique challenges for NOSA, SFL and TNO. For NOSA and TNO, specifically, it meant that they needed to develop what was described in the release as “a high-quality onboard laser terminal with a fine steering mirror that locks the extremely narrow optical beam onto a ground station beacon.”
According to NOSA Senior Advisor and NorSat-TD Project Manager Tyler Jones, TNO was responsible for developing the payload as they “have a leading position in the field.” They were joined by Norway’s KSAT, who are “a leading operator of the most comprehensive commercial satellite ground network,” he said. with the intention of eventually adding these optical capabilities to KSAT’s NUCLEUS optical network. SmallCAT is intended partially as a technology test for NUCLEUS, and he said that TNO is currently integrating an appropriate ground station into NUCLEUS.
TNO’s Erik Fritz elaborated on the SmallCAT and its Netherlands-based development consortium. In addition to TNO and KSAT, he said that AAC Hyperion handled the electronics and software, while Gooche and Housego were responsible for the laser. Overall architecture and integration was done by TNO. In terms of SmallCAT itself, he said that it featured two main parts: the optical terminal for CubeSats (called CubeCAT), and a suspension system appropriate for the mission’s launch loads. CubeCAT allows for 1 Gb/s transfer speeds, and he said that he expects that AAC Hyperion will ultimately be bringing the CubeCAT to market when testing is complete.
Jones said that SmallCAT was, however, only one of a variety of in-orbit demonstration payloads on the satellite. Several payloads from Norway also involved communications: Space Norway is testing a VHF Data Exchange (VDES) terminal, and performing tests that “demonstrate VDES-enabled maritime navigation and GNSS integrity monitoring,” and Kongsberg Seatex contributed a payload that collects Automatic Identification System messages from a “high-performance CubeSat AIS/IoT Receiver.”
France’s ThrustMe is also testing a new iodine ion thruster, Italy’s SCF_Lab is testing satellite laser ranging, and Norway’s Fugro is verifying “sub-decimeter augmented GPS positioning,” said Jones.
Testing of these other payloads is still ongoing.
SFL and NorSat-TD Integration
This all led to a significant challenge for SFL: manage these distinct payloads and their unique requirements, while still managing to provide the capability to handle the delicate and tricky task of performing laser-based communications from such a micro-sized satellite.
Jacob Lifshits, Senior Mission Manager at SFL, provided more details.
Lifshits acknowledged that the biggest challenge to SFL was “the accommodation of each payload’s unique requirements and operational constraints,” including SmallCAT, while ensuring “each [would] meet their goals without compromising the performance of others.”
In order to overcome this challenge, Lifshits said that SFL performed detailed mission analysis regarding NorSat-TD, then designed and manufactured the satellite based on NOSA’s requirements. Lifshits said that the satellite generally uses tried-and-trusted technology from SFL, including their well-known DEFIANT platform. He credited the “flexibility” of the platform for their success.
Lifshits said that, in fact, the satellite was “manufactured, integrated, and tested in SFL’s facilities in Toronto.” He added that “the majority of the satellite components and subsystems [for NorSat-TD] were developed in-house by SFL,” including “flight computers, various attitude control sensors and actuators, the power system, deployable structures, etc.”
SFL also arranged for the launch, performed launch vehicle integration, and supported NOSA with commission of the satellite. NOSA is responsible for mission operations, however, and arranged for the payloads to be delivered to SFL for integration.
Lifshits said that one key technological focus when building the satellite was “an extremely precise and stable attitude control system,” and the release also noted that the satellite includes what they called “barrier-breaking small satellite stability and pointing capabilities” to accurately and continuously point at a ground station as the satellite passed overhead at 7.5 km per second. While the attitude control system used on NorSat-TD was the same one used in other SFL satellites, this was the first SFL satellite of its size to contain an optical communications terminal, and to overcome these “barrier-breaking” requirements.
This contribution of SFL technology also extended to the other payloads, Lifshits said, including “[deployable] antennas for [the] AIS receiver, IoT receiver, and VDES terminal.” He added these were sizable antennas for a CubeSat, particularly one that was adapted from NorSat-2, and that he believed that “the capability to deploy such a large antenna from a microsatellite is truly an enabling technology.”
Lifshits closed by saying that they’re excited by the capabilities of optical communications—citing the higher throughput and security—and that integration of these capabilities could be beneficial for a number of satellite data applications, particularly earth observation and telecommunications.
“While optical communications terminals can be readily found on larger satellites,” Lifshits said, “they are still uncommon on microsatellites such as NorSat-TD.” Now that NOSA and SFL have proven the viability of the technology on microsatellites, others may follow suit, which will “open the door to new applications which can be serviced by smaller and more economical platforms.”