CAN WE USE LOW-COST SMALL SATELLITE TO OBSERVE SPACE DEBRIS MISSED BY GROUND SYSTEMS? Peter Senior (1) , Steve Eckersley (1) , Victoria Irwin (1) , Ben Stern (1) , Andrew Haslehurst (1) , Andrew Cawthorne (1) , Alex da Silva Curiel (1) , Sir Martin Sweeting (1) (1) Surrey Satellite Technology Limited, Tycho House, 20 Stephenson Road, Surrey Research Park, Guildford GU2 7YE, United Kingdom, Email: info@sstl.co.uk ABSTRACT There is still a range of debris objects that can only be observed from space. An industry perspective on the space debris problem is provided, particularly on the major requirements of a space-surveillance system. We show that low-cost small satellites have a valuable part to play in the monitoring of this global problem, providing unique viewing opportunities and filling in the blind spots of ground-based systems. The trade-offs between instrument size, instrument agility, and platform size are key to delivering a cost-effective solution. Two viable small satellite concepts are presented, balancing cost and capability, which illustrate how these requirements can be effectively answered. 1 Introduction This paper will briefly cover space debris, its detection, and its mitigation from the perspective of Surrey Satellite Technology Limited (SSTL). Based in Guildford, UK, SSTL is a vertically-integrated small satellite manufacturer with over 30 years of experience in space, which has included building spacecraft from 3 to 3000 kg and from low orbit (LEO) to geostationary orbit (GEO) and beyond. We will discuss common requirements for space situational awareness (SSA), also called space surveillance and tracking (SST), and how these requirements affect a system engineer’s understanding of the solution space. Reasons for and against space-based systems are presented, as well as the variety of technologies available for SSA missions. The paper will then focus on space-based systems, and their key design choices and drivers. Finally, two interesting low-cost concept solutions from SSTL will be presented along with their design rationale. 2 Background We present here some brief background from SSTL’s perspective on space debris. 2.1 Operational Impacts From SSTL’s extensive operational experience of over 500 satellite-years in orbit, on average each satellite has to perform a manoeuvre every year or two, with the number of conjunction warnings increasing over time. The improvement in conjunction analysis tools has decreased the number of manoeuvres required, however there is still a need to sift the ever-increasing number of conjunction warnings which require further investigation. The vast majority of our satellites are in polar sun-synchronous low-Earth orbits, which are some of the most congested regions of space. Fig. 1shows a plot of the density of objects larger than 10 cm and the locations of major ESA missions in LEO. Debris larger than 10 cm can completely destroy a satellite [1]. The most recently available statistics at time of writing were that there are 34,000 objects of this size in orbit [2]. Figure 1: Operational ESA missions in LEO compared with the spatial density of objects > 10 cm from [3] The impact of very small debris and micrometeorites (<1 mm) results in the degradation of spacecraft surfaces, particularly solar cells. The expected degradation is designed into the satellite with an additional margin for the solar cell area. The need to avoid larger debris adds a slight increase to the propellant required for missions in these regions. A more significant impact resulting from debris avoidance is the outage required to manoeuvre the satellite to avoid debris. Often a debris avoidance manoeuvre is combined with orbit maintenance manoeuvres, which reduces the overall manoeuvre Proc. 8th European Conference on Space Debris (virtual), Darmstadt, Germany, 20–23 April 2021, published by the ESA Space Debris Office Ed. T. Flohrer, S. Lemmens & F. Schmitz, (http://conference.sdo.esoc.esa.int, May 2021)