Introduction

The International Space Station (ISS) is an exclusive scientific podium and an orbiting laboratory that has facilitated interdisciplinary researchers in 106 countries to conduct various in vitro trials in microgravity. Although each ISS partner has diverse scientific objectives, the aggregate aim is to encompass the experience and knowledge garnered to benefit all humankind [1, 2]. This is predominantly factual for nurturing medicinal plants in ISS for scarce-drug discoveries for the benefits of humanity [3]. This article is a part of the scientific odyssey that resulted from a collaboration among members from various research groups from physical, chemical, material and biological sciences. Literature review reveals that through fundamental research and development a few products and services derived from space station activities are entering the souk and furthering healthy and peaceful life on Earth [1], which is motivating us to propose more challenging research in ISS. It is evident from the executive summary of ISS, which encapsulates the achievements of innovative research on the orbiting laboratory that had created a positive impact on the quality of life on Earth and the future scope of the interdisciplinary researches globally for creating an impact on scientific advancement [1-16]. Herein we conduct theoretical studies for providing the proof of the concept of space debris recycling and energy conversion system in a microgravity environment with an intention to carry out real-time experiments in the space platform through the multi-national collaboration with wide scope and benefits to humanity.
The growing utilization of outer space for the advancement of the standard of living and hunt for wisdom has led to the accretion of space debris or space junk in high-density satellites orbits. Various reports and industrial engineering data on the usefulness of the prevailing debris extenuation methods are inadequate for a realistic conclusion [4-16]. J.-C. Liou et al. [4-8] reported that as the space debris volume remains to rise over time due to the global space activities in recent years, there is a need to update the debris alleviation normal exercises to stimulate competent and active practices to better abate the risks from space debris for the benign manoeuvres of future space missions. Literature review reveals that the frequency variations of orbital launches are due to the in-house reasons in the participating countries [17]. The current trend of rocket launches globally shows that in the next few decades’ large volumes of space debris will be in orbit, which will create a serious threat to future missions. It is comprehended by other investigators that albeit all upcoming space launches are called off, the space debris already exist will be tendering threats for numerous decades to come before all of them re-enter earth and burn off [14-17]. Deepaa Anandhi et al., [17] reported the need for an urgent action on the space debris mitigation independently or jointly by the various beneficiary organizations utilizing the orbital space for meeting the future global needs. Though numerous on going debris de-orbiting programs are intact, the engineering data on the usefulness of the prevailing debris extenuation procedures are inadequate for a reliable judgment [18]. Briefly, an enhanced volume of space debris has become a menace to live satellites, ISS and various space missions. Although many studies have been reported over the decades on space debris management and alleviation, the space system designers reported that there are no foolproof techniques for tracking and mitigation of space debris having the object size between 1 cm and 10 cm, which could cause significant damage to live satellites, future space vehicles and the ISS [18]. Although every space agency is persuaded to reduce space debris whenever feasible by using their state-of-the-art modus operandi, there may be some parts that would be liberated and orbiting for obvious causes beyond control. This situation was observed by many space agencies when a physical part of the space vehicle was departed in geostationary transfer orbit (GTO) during a multiple payload mission [10]. Therefore, it is essential, rather enviable, perhaps predestined for inventing lucrative and efficient methods of space debris mitigation. United Nations (UN) Committee on the peaceful uses of outer space reported that the most challenging part of the space operations is the collision avoidance. It also reported that the space debris curing issues certainly entails joint action by all participants [11].
The central idea of the space broom governed by the dual-head electromagnetic (DHEM) device [19], is to mitigate the intermediate size of the space debris object, which could otherwise pierce holes in the structure of the ISS and live satellites, particularly in the low earth orbit. It is estimated that the space debris could crash any space vehicle at a velocity greater than 48,280 km/hr [18]. Hao Jiang et al. [20] carried out tests in microgravity and reported that robotic grippers based on dry adhesion are a workable option for purging space debris in low Earth orbit. The DHEM space broom with variable sweeping speed developed by V.R.Sanal Kumar et al. [19] could be a useful method for the space debris mitigation and its collection for recycling it in the orbiting space lab through the lucrative energy conversion methods. The DHEM space broom could be redesigned for capturing the inactive satellites, rocket fragmentation debris, and other non-functional objects or debris pieces from the low earth orbit. The environmental report (2019) of the European Space Agency (ESA) highlighted that space debris mitigation requires a level playing field to achieve long-term stability. The ESA highlighted in its annual space environment report (2019) that the production of space debris via impacts and blasts in orbit could lead to an exponential growth in the volume of artificial objects in space [21]. Therefore, the menace of space debris to the future of spaceflight, united with the closely world-wide embracing of the U.N convention (1972) on global accountability for damage caused by space objects, created the need for a set of internationally accepted space debris mitigation measures [22]. Recently the ESA emphasized the need of world-wide devotion to invoking space debris alleviation measures lucratively. The accessible global literature reveals that no one attempted yet (2020), the recycling technique to change the debris into powders in the ISS for multiple applications [14, 15].
Report (2019) reveals that India contributed around 400 pieces of orbital debris through their anti-satellite missile test (ASAT), which increases the risk of threat to the ISS on the order of 44 % [18]. Since the test was done in a low altitude to restrict the orbital lifespan of ensuing debris, the space agency claimed that whatever debris that is generated would decay and fall back onto the earth within weeks and the ISS will not be at risk, as it is in the higher orbit. However, there are possibilities of the orbital lifting of space debris due to missile impact, which could create threat to the ISS. Therefore, in future such tests must be avoided by all the space agencies or must be done with caution as the ISS is a human inhabitant and an orbiting laboratory, which is to be protected with zero-risk. It is well known that the non-responsive satellites are the high-risk space debris to the operational satellites and the ISS. The primary structure of most of the satellites consists of aluminum, beryllium, stainless steel and titanium. The appendage booms, antenna dishes (made of aluminum / steel), platforms, solar panels (made of silicon / germanium), and support trusses, are common secondary structures. The mounting brackets, cable supports, copper wiring and connector panels, electronic boxes, and silicon made printed circuit board (PCB) are categorized as tertiary structures [23]. Literature review reveals that Aluminum 6061, a potential fuel for solid propellant, is used as the primary structure of the CubeSats [24]. Therefore, any combined method to mitigate and recycle the space debris with an innovative energy conversion method could create a win-win situation, which is attempted herein.
In this paper a cogent conceptual method has been proposed for converting the space debris into lucrative solid fuels in the ISS with artificial gravitational field. Note that M.Tajmar [25] reported two different system designs that could generate an artificial gravitational field using frame-dragging or gravitomagnetism. It is known that frame-dragging is an effect on spacetime, predicted by Albert Einstein’s general theory of relativity, which would be used to generate artificial gravitational fields similar to electric fields generated by time-varying or moving magnetic fields with enhanced field strength [25].
The space broom operated by a DHEM device is used for capturing the space debris from the space environment [19]. An optical sorting method will be used in the ISS for segregating the collected debris into individual material and metal scraps. Using an electric channel induction furnace, the separated metal scraps are converted into the molten metal form. Further, a lucrative water atomization system operated with a fuel cell has been adopted for converting the molten metal into powder form, which produce the end products, viz., the metal powder and the water. The segregated selected powders are utilized for making solid propellant for chemical propulsion. The specially separated silicon powders are used for building feigned soil for nurturingpharmaceutical flora in the ISS for the scarce drugdiscovery for the high-endurance health care management [3, 26-28]. An inclusive layout of the proposed methodology for space debris mitigation and the energy conversion technique are described in the subsequent section.