Novoseltsev D. A.
On the possibility of rational utilization of fragments of near-Earth space debris and meteoroid matter using kinetic jet engines
At present, the accumulation of space debris (SD) in near-Earth orbits, primarily in the most actively used ones, is beginning to pose a significant problem. While maintaining the current trend of its accumulation and increasing the total number of spacecrafts in operation, in the near future the SD may pose a threat of damage to the spacecrafts, many times exceeding the threat of collision from fragments of natural meteoroid bodies, and can significantly complicate space activities.
Passive methods of spacecrafts protection from SD due to different variants of their armoring are ineffective in most cases and significantly worsen their mass characteristics.
Active methods of protection against SD, with all their diversity, are mainly aimed at braking sufficiently large fragments of debris, reducing their orbit and subsequent destruction in the atmosphere. Such an approach cannot be considered either sufficiently effective or rational. With the mass efficiency of spacecraft launch vehicles characteristic to date, the payload is about 2% of the launch mass of the launcher - about 50 kg of the launch mass of the launcher, mainly fuel, with the corresponding environmental load on the medium, was used to give the orbital speed to each 1 kg of SD. The destruction of this piece of debris also requires the development and manufacture of a specialized spacecraft, and its insertion into an appropriate orbit, including environmental costs.
Even less effective are known proposals for the collection and processing of SD – due to the relatively small mass of its individual fragments moving along different trajectories, such activities are much more complicated compared to the recently considered hypothetical mining on asteroids and other sufficiently large celestial bodies.
The problem is complicated by the fact that the reduction of the threats of collision of SD with spacecrafts by known methods cannot be commercialized at present, and in this regard is of interest only for states or large companies engaged in space activities, for the limited protection of the most valuable spacecrafts.
As a rational variant of economically expedient utilization of SD fragments, it is proposed to consider the possibility of its use as an external source of energy and a working substance for spacecraft maneuvers using a kinetic jet engine (KJE). The concept of KJD is stated in a number of articles [1, 2] and finally formulated in the form of a “kinetic sail” by Podvysotsky and Panov . The proposed design is essentially similar to the concept of a pulsed nuclear rocket engine with a sail, developed in the United States within the framework of the “Medusa” project , based on the implementation of the explosion in the focus of the sail, followed by the transmission of the impulse of the expanding products of the explosion of the inner working surface of the sail. With a sufficiently large sail area, the dynamic and thermal load on its structure does not exceed the permissible values for the structural materials used.
“Kinetic sail” involves the use of energy is not nuclear, and kinetic explosion, in the classical model of V. V. Podvysotsky – in a controlled collision of specialized spacecrafts ("probes") with "targets" in the focus of sail . In case of utilization of SD in KJE function of "probes" is performed by fragments of SD, and "target" is located on board of spacecraft. The most probable use of the KJE are single-pulse inter-orbital flights, although with additional propulsion engines and gravitational maneuvers spacecraft with KJE possible for further travel within Solar system and beyond.
In a frontal collision of a fragment of SD with a target at their counter motion with orbital velocities, the specific kinetic energy of the collision will be about 1,3x108 J. With the specific heat of combustion of traditional chemical rocket fuels of the order of 107 J / kg, the use of 1 kg of SD and 1 kg of the material of target on board the spacecraft is energy equivalent to the use of 10-15 kg of fuel on board the spacecraft for a similar maneuver, and taking into account the efficiency of the launch vehicles – more than 500 kg of the launch mass of the launcher. In this case, the utilization of SD in the KJE is economically feasible, and can be commercialized in the implementation of space activities, including relatively small private companies.
The use of unmanaged fragments of SD or the natural meteorite bodies in the KJE instead of managed "probes" requires very accurate data about their mass and coordinates. But the solution of this problem for the entire array of KM in the near – earth space in any case is relevant for the near future-at least to ensure early evasion maneuvers of particularly valuable spacecrafts.
In addition to the absence of formal legal prohibitions on their practical implementation, the advantages of the KJE compared to pulsed nuclear rocket engines of the “Medusa” type are the exclusion of the radiation impact of the explosion on the structure and payload, as well as the absence of restrictions on the minimum power of the kinetic explosion (as opposed to nuclear). The latter not only greatly simplifies the experimental flight testing of the KJE, but also allows the use of small fragments of SD for interorbital flights of the currently popular nano- and femtoclass spacecrafts, as well as a new type of StarChip .
In the future, the development of the Solar system may be more widely used in KJE so bodies with large masses and orbital velocities. Thus, it may be appropriate to use the objects that make up the outer rings of Saturn to launch massive payloads into the outer region of the Solar system and beyond with the using of KJE.
- Valentin Podvisotsky. Kinetic jet engine mode of application. Space Colonization Journal, Issue 2, 2015, pp. 1-16.
- Alexander Panov. On the possibility of using the Podvysotsky kinetic engine for flights within the Solar system and to create an interstellar probe. Space Colonization Journal, Issue 5, 2014.
- В.В. Подвысоцкий.Некоторые способы использования космического паруса. 22 с. http://lnfm1.sai.msu.ru/SETI/koi/articles/86.pdf.
- Johndale C. Solem. Some New Ideas for Nuclear Explosive Spacecraft Propulsion. LA-12189-MS, October 1991. https://fas.org/sgp/othergov/doe/lanl/docs1/00189777.pdf.