A Low-Cost Launch Assistance System for Orbital Launch Vehicles

Hindawi Publishing Corporation International Journal of Aerospace Engineering Volume 2012, Article ID 830536, 10 pages doi:10.1155/2012/830536 Review Article A Low-Cost Launch Assistance System for Orbital Launch Vehicles Oleg Nizhnik ERATO Maenaka Human-Sensing Fusion Project, 8111, Shosha 2167, Hyogo-ken, Himeji-shi, Japan Correspondence should be addressed to Oleg Nizhnik, Received 17 February 2012; Revised 6 April 2012; Accepted 16 April 2012 Academic Editor: Kenneth M. Sobel Copyright © 2012 Oleg Nizhnik. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The author reviews the state of art of nonrocket launch assistance systems (LASs) for spaceflight focusing on air launch options. The author proposes an alternative technologically feasible LAS based on a combination of approaches: air launch, high-altitude balloon, and tethered LAS. Proposed LAS can be implemented with the existing off-the-shelf hardware delivering 7 kg to low-earth orbit for the 5200 USD per kg. Proposed design can deliver larger reduction in price and larger orbital payloads with the future advances in the aerostats, ropes, electrical motors, and terrestrial power networks. 1. Introduction Spaceflight is the mature engineering discipline—54 years old as of 2012. But seemingly paradoxically, it still relies solely on the hardware and methodology developed in the very beginning of the spaceflight era. Modernly, still heavily-used Soyuz launch vehicle systems (LVSs) are the evolutionary improvement of the R-7 rocket which launched the very first Sputnik satellite. Although many advanced rocket concepts were proposed and even implemented (most notably the Space Shuttle), these designs did not stand the test of the time. The comprehensive review on the current state of art in field of rocket propulsion can be found in [1]. Nonrocket-based spaceflight was also heavily researched, but the research did not result in practical systems other than the Pegasus LVS which is scheduled for retirement. The main reason why nonrocket spaceflight schemes were not widely implemented yet is their failure to compete with the purely rocket spaceflight schemes in the field of the orbital delivery of the high-value payloads like communication satellites or interplanetary probes. But baseline rocket cost denies many less valuable yet desirable payload classes like orbital power or industrial plants or machinery for extraterrestrial resources utilization. To ultimately enable these payload classes, an interim prototype of the nonrocket launch assistance system (LAS) should be developed to launch experimental payloads. Therefore, an economically viable systemlevel design of the LAS delivered in this paper may be key point to the progress in the orbital delivery systems for these additional payload classes. 2. Overview of Previously Proposed LAS A lot of proposals have been made to implement nonrocket LAS and are listed in Table 1. The Rumanian Space Agency/ARCASPACE [2] has proposed to launch a moon probe from a high-altitude balloon. If the rocket start altitude of 20 km can be reached, a very light-weight, cheap launch vehicle may be possible. However, at the 20 km altitude, each ton of the rocket needs at least 200,000 m3 for the volume of the solar-heated Montgolfier balloon as proposed by ARCASPACE. So the design of an ultrahigh-altitude ARCASPACE balloon is expensive and technically challenging task. Furthermore, such a huge balloon is expendable, and the long ascent time requires usage of storable propellants in the rocket. Also, ARCASPACE balloons can be launched only in sunny weather, implying delay costs. Finally, their position during the launch is uncertain, complicating the safety area. The electromagnetic launchers (railguns) for accelerating a small payload from LEO were also proposed [3] in the wake of the SDI program. But the railgun is an intrinsically very high-power device (30–1000 TW in proposed configurations). Such power levels impose weight penalties for the structural and energy storage materials, as well as the distribution and dissipation elements, making orbital 2 International Journal of Aerospace Engineering Table 1: Previously proposed launch assistance systems. Method High-altitude free-floating Montgolfier balloon Orbital electromagnetic catapult Laser ablation drive Space elevator LEO rotovator Spiral sling (slingatron) Interplanetary rotating tethers Rotating, tension supported ring Electromagnetic tether for raising orbit Space fountain Ground-based linear accelerator (gun, catapult) Subsonic launcher aircraft Precooled air ramjet launcher aircraft Supersonic launcher aircraft in general References [2] [3] [4–6] [7, 8] [9–11, 13] [14–18] [19–29] [30] [31–33] [34] [36–39] [40, 94] [42, 43] [41, 44] railguns uneconomic. Railgun devices in [3] are capable of launching 0.3 kg payloads with speeds 4–10 km/s (realistic with existing technology), but the launcher itself is likely to weigh more than 300 tons (because at least 200 tons are needed for capacitors alone), with a 5,000-ton weight being a more likely estimate. An initial proposal for a rocket engine based on the heating of propellant by remote laser was made in [4]. But given the low continuous power of available lasers (below 1 MW level) and bad transmission efficiency, such propulsion method requires many improvements in laser technology beyond the current level. In [5] the power requirement for beamed-energy propulsion from Earth to orbit is estimated to be 0.1–1 GW of continuous beam power per ton of the vehicle mass, which is 3-4 orders of magnitude higher than current state-of-art laser transmitters. As a consequence, the best altitude reached by a beamed-energy aircraft in 2001 was only 71 m [6]. Space elevator system is perceived a viable solution [7] but it is far from being possible with the current material technology [8]. Rotating tether systems [9, 10] can be useful for the reduction of the delta-v from earth’s surface to orbit. But the required spaceship guidance accuracy to enable rendezvous with the rotating tether tip is higher than the task guiding an antisatellite missile and cannot be performed reliably with current guidance technology. Normal rocket LVSs are not agile enough for the last-second speed vector adjustments. In [11] a more robust rendezvous method using a motorized grapple was proposed. It has the advantage that a highagility engine system is placed on the tether grapple; thus extensive redesign of the rocket LVS propulsion system is not necessary. But for a practical rendezvous time window of 10 seconds with a realistic 25 km long, 1.6 km/s tip speed tether, a rendezvous motor must provide a delta-v of at least 500 m/s for compensating the lateral mismatches. The grapple also must include a 50 kW power motor per 1 kg of grapple w (...truncated)