## 1 Introduction  
Most space debris observation and tracking are done by the Space Surveillance Network, constituted by a set of over 30 ground-based optical and radar telescopes located worldwide, and six satellites that regularly track objects in orbit and maintain a catalogue of about 32,000 objects. These observations have a size limitation ranging from 10 cm in Low Earth orbit (LEO) to about 1 m in Geostationary Earth orbit (GEO). The catalogued objects represent a tiny amount of the total since statistical-debris environmental models estimate more than 131 million space objects ranging from 1 mm to 10 cm [1; 2; 3]. Star trackers (STRs) are one of the most accurate attitude sensors developed for modern spacecrafts used to determine the attitude by detecting stars in the STR's field of view (_FOV_). STR architecture consists of an optical system, an image sensor, electronics, and a signal-processing system. The optical system is composed of a set of lenses and a light called the Baffle, which protects the STR from light that affects its functioning, such as Sunlight. The image sensor, responsible for taking the observed objects' images, can be a Charge Couple Device (CCD) or a Complementary Metal-Oxide-Semiconductor (CMOS). The drivers and controllers, i.e., electronics and signal processing systems, comprise the processors and software, namely, controllers and drivers that control and operate the hardware [4; 5; 6; 7]. STRs used to be a high-technology device with a high cost. With the advent of New Space activities, new studies that use COTS (Commercial Off-The-Shelf) equipment in STRs to reduce the size and cost have been performed in the last years. An STR for small satellites and CubeSats should ideally have as high of an accuracy as possible and minimal power consumption, volume, and mass. However, this is hard to obtain. For example, better optics or an image sensor with a higher resolution can improve the STR accuracy. Still, better optics require more volume and, consequently, more mass. A higher-resolution sensor, on the other hand, requires a larger memory and a better processor. Hence, the selection of the components has lower and upper limits to maintain the characteristics of the system [8]. Table 1 lists some examples of COTS STRs. Due to good results, CubeStar [9] was developed and implemented in CubeSat missions, and it is commercially sold nowadays. The SOST [10] platform passed the laboratory tests for vibration and thermo-vacuum conditions, but it has not been evaluated in space. APST [6] shows good ground-based observation results, detecting stars up to 5.85 in magnitude. Furthermore, these studies suggest that the lens of an STR should have a low-focal number, in the order of 1.2 to 1.8, to produce bright images. Also, an STR must have a large \(FOV\), varying from 10\({}^{\circ}\) to 40\({}^{\circ}\), since this characteristic has advantages like lower memory, less computational time, and moderate accuracy. Lastly, a CMOS sensor is preferable compared to CCDs due to the advantages of lower power consumption, radiation resistance, and lower price. Besides attitude extraction, some works demonstrate the capability of STRs and space cameras in space-debris detection. [PERSON] [11] did a feasibility study using a COTS STR to detect resident space objects (RSO) by developing a simulator to evaluate the capability of STR detection. The conclusion shows that a dedicated STR, used only for RSO detection, is feasible and can detect more than 1200 objects/day. However, a dual-purpose STR, a device that extracts the attitude and detects RSOs simultaneously, did not achieve concrete results. [PERSON] et al. [12] propose a feasibility study using a network based on multiple STRs for space-debris detection and monitoring, establishing an algorithm that uses the images taken by STRs on satellites during attitude fixation to detect and extract space targets to increase the available data information of space target surveillance.