# TrackInk: An IoT-Enabled Real-Time Object Tracking System in Space
## 2 Related Work  
There are several proposals that address the issues of location tracking [56; 57]. Many of them used techniques, e.g., radar-based satellite tracking, telescopic optical detection of space objects, etc. For instance, proposal [58] discusses the use of reflected radio signals transmitted by the Graves Radar to detect and track objects in LEO with the use of a low-cost directional antenna. The proposed system can validate TLE data of the ISS and detect objects with a mass over one ton. With this device relying on the Graves Radar to operate, it is geologically dependent and would need to be re-calibrated if moved.  
Proposals [59; 60] present the use of a camera attached to a telescope for optical detection of space objects. Both proposals achieved this by calibrating the system to a background image of the night sky, and performing computer vision algorithms to detect objects. This system is sufficient to detect objects in orbit, but is limited because it can only be run during night-time, and it also has a limited field of view compared to our proposed TrackInk system. With a similar objective to [59; 60], proposal [61] discusses the use of a servo-actuated telescope to track the ISS using TLE data, visually verifying that the system is accurate. However, unlike our proposed approach, in this proposal, the telescope-servo apparatus lacks portability, both in the sense of its size and lack of environmental sensors to orient itself regardless of location.  
One other article, [62], discusses the use of TLE data for satellite and planetary tracking for image capturing. This work discusses using the SGP4 algorithm to convert altitude and azimuth to actuate a telescope and camera. Computer vision is then performed to further improve the tracking of the object. The work discussed in this article requires an initial configuration in which the device must be placed level and pointed North, which is not required by our proposed TrackInk system. Another proposal discusses the use of a permanent optical ground station utilising an actuated telescope and camera apparatus [63]. This apparatus is used to perform image analysis to estimate the spatial distribution of satellites in LEO. However, unlike these systems (i.e., [62; 63]), our proposal presents a simple, cost-effective, and lightweight solution for object tracking in space.  
Proposal [64] discusses a decentralised approach for managing telescopes for satellite tracking. This proposal utilises the many telescopes around the world to manage and track active satellites along with other space debris. It focuses on the management of pre-existing telescopes, specifying what tasks should be done at a given time. However, it does not discuss the significant issue of portability of individual devices, which our proposed TrackInk framework provides.  
In [65], the use of optical telescope observations to monitor the distance between two geosynchronous satellites, Turksat 2A and Turksat 3A, is discussed. It is discovered that an optical system is sufficient to compare the orbital paths of the two satellites and validate their simulation models. In addition, the system allows for live system analysis, which would be necessary if any perturbations caused the satellites to approach each other's orbits. Similarly, another geosynchronous satellite, WINDS/Kizuna, is tracked in [63] using an optical telescope, using stars as a reference in space. Both of these articles utilise large permanent observatories for their sensing, which results in high costs that our proposed system avoids. Utilising shared observatories also means limited use of the telescope, which could be a detriment to the research done, which is not an issue for the low-cost implementation of our proposed TrackInk system.