Integration, launch and deployment
EagleEye is a groundbreaking mission from the point of view of Polish space sector – the satellite weighs as much as all the other Polish satellites that have been launched so far. The mission involves our SOP200 telescope, which has the ability to image the Earth’s surface with a spatial resolution of about 1.75 meter in the visible (VIS) and near-infrared (NIR) spectrum from 500 km altitude.
The project has been underway since early 2020, and will culminate with the satellite’s launch in just a short time, in mid-2024. During the entire project, the engineering team has carried out a number of test campaigns – vibration, thermal-vacuum and stratospheric tests to demonstrate the validity of the design and to test the improvements applied.
Integration
Integration is the post-design phase of a project, during which is intended to integrate all designed and manufactured components. The integration is performed several times throughout the project (we wrote about model naming earlier HERE), but for simplicity’s sake, let’s just talk about flight model integration.
Integration of a flight model differs fundamentally from integration at earlier stages – due to the fact that this is being done for the last time, much more care is required. It is often the first time that components and flight versions of subsystems are being assembled, which, even though very accurate mock-ups have been made (for structural or thermal models), may differ slightly in size or mechanical interfaces – both due to inaccurate manufacturing and unreconciled design changes.
It is also the first time to connect the appropriate cable harnesses, which can also cause their own separate problems. Since not all of them have been connected before, there may be problems with their routing. They also need to be rigidly attached to the structure at dedicated locations (mechanical interfaces), or glued with a special tape – kapton, but also protected from interruption caused by vibration – this is done both by wrapping the bundles in the exposed areas with an additional layer of tape, and also tape the structure itself at the sharp edges. It is a good practice to use chamfers at the expected locations of the bundles.
In addition, the functionality of all intended functions of the device must be checked, and it must be ensured that there are no short circuits between the electronics and the structure. Short circuits can adversely affect the electronics and, in extreme cases, can cause complete damage to the electronics, resulting in the loss of some functionality of the device or the entire mission.
Since the vehicle will never be disassembled again, it is important to ensure that all telescope bolts are tightened to the correct torque, as well as sealed with special glue, which strengthens the strength of the connection by making it resistant to loosening caused by overloads and vibrations during the rocket’s launch.
Once the entire object which is being launched into orbit is assembled, the final functional tests confirming the correct integration take place, followed by vibration and thermal-vacuum tests, about which you can read more HERE. Only at this point is the vehicle sent to the launch site, where it is integrated with the rocket – engineers integrate adapter on the vehicle together with the so-called separation ring (deployment ring), which is attached directly to the rocket, or to the hardware provided by company responsible for providing the separation system and releasing the vehicle at the appropriate moment of the rocket flight.
Launch
SOP200 telescope will be launched as early as the middle of this year, with SpaceX’s Falon 9 rocket. This is a rocket with a first stage capable of multiple launches (the record first stage at this point has more than twenty launches and landings). Scanway’s telescope is integrated with a satellite of the same name, the construction of which is the responsibility of a consortium headed by Creotech Instruments S.A – this company is responsible for the development and delivery of the entire satellite platform. In addition, the project also involves the CBK PAN (Space Research Center of the Polish Academy of Sciences), which provided an advanced on-board computer for processing data from the telescope.
The telescope will be flown into orbit during the Transporter-11 mission, a shared mission with other small satellites. With this arrangement, the cost of launching a payload is spread among the operators of all payloads – during the previous Transporter missions, as many as 143 satellites were launched simultaneously.
The rocket launch will take place from the Vandenberg military base in California. EagleEye will go into a heliosynchronous SSO orbit (you can read more about the types of orbits HERE) with a target altitude of about 350 km above the Earth’s surface. The satellite and its telescope will initially be separated from the rocket in a higher orbit, and it will be possible to reach the target orbit by using an engine placed on the satellite, with the help of which the orbit altitude will be reduced. Operating in a lower orbit will make it possible to take images of the planet’s surface with greater accuracy and resolution, which will allow greater detail to be visible in the images.
A heliosynchronous orbit (SSO) is a type of low Earth orbit (LEO), whose unusual inclination and characteristics let it be classified separately. Compared to ordinary orbits, vehicles move from north to south (high inclinations of the orbits), compared to the west-east direction with standard low LEO orbits. The choice of orbit height and inclination defines the number of orbits a spacecraft will travel through space per day. A characteristic feature of an SSO orbit is that the vehicle passes over the same location at the same mean solar time each time. This is particularly important from the point of view of Earth observation, since the same lighting conditions are present in the images taken – e.g. the shadows cast by buildings are each time practically the same length, which, when the length of the shadows change, can suggest varying building heights due to, for example, construction progress.
Deployment
About an hour after the rocket’s launch, satellite separations (deployments) from the rocket will begin. EagleEye has already been integrated with the separation system, provided by an external company. Immediately after the integration, the final functional tests took place, which confirmed the correct operation of all subsystems of the vehicle.
At the time of launch, the so-called LEOP phase – Launch and Early Orbit phase – begins. This is the phase of the mission during which the actual launch of the mission into orbit takes place, but also the separation from the rocket, and successively the start-up processes and testing of all the vehicle’s systems.
Immediately after separation from the rocket, the so-called detumbling of the vehicle, that is, stabilizing its orientation in orbit, must take place – immediately after separation, chaotic movements may occur, making it impossible to both establish contact and obtain useful data. Only after the movement is stabilized will a connection be established with the vehicle in orbit.
After an initial check of the systems, operators will begin to lower the satellite’s orbit. After reaching the target orbit of about 350 km above the Earth’s surface, Scanway’s telescope will be able to take images with the target spatial resolution, since this parameter strongly (linearly) depends on the height of the orbit.
On-orbit operations
After the LEOP phase, i.e. commissioning the telescope’s basic functions, the normal use phase will begin. The telescope will make it possible to observe changes on the Earth’s surface, both those caused directly by human activity – new developments or climate change, but also others, such as climate disasters. Having comparative data will give researchers the ability to determine the rate of change, and services the ability to react quickly and determine the scale of the problem.
In the case of extremely large natural disasters, satellite data may be the only data available to emergency services due to the lack of communication with the affected region. Such a situation occurred, for example, during the eruption of the Hunga Tonga-Hunga Ha’apai volcano in 2022, during the eruption of which a tsunami destroyed an underwater fiber optic cable, cutting off the island nation’s communications from the rest of the world.
Also taking into account the instability of the political situation in the region and around the world, having Poland’s own optical system in orbit will allow independence and freedom of action in selecting the area to be observed. Moreover, it will give immediate access to all data, unrestricted by external partners.
Summary
The imminent launch of the EagleEye mission with our telescope shows that we are capable of delivering complex space payloads on a regular basis. Following the success of the STAR VIBE mission and the validation of the optical design, improvements were made, resulting in the final EagleEye design enhancements. At launch, it will be the largest Polish optical payload deployed in space.