[INTERNATIONAL JOURNAL FOR RESEARCH & Volume-4,Issue-3, Sep - 2015 DEVELOPMENT IN TECHNOLOGY] ISSN (O) :- 2349-3585 Ensuring the Safety of Manned Spacecraft during Launch Phase R. Duch 1 1Department of Avionics and Control Systems 1Rzeszów University of Technology, Rzeszow, Poland Abstract — This paper presents issues related to the safety of The astronauts had no prospect of rescue due to lack of escape manned rocket launches. It introduces the reader to the system, although the crew cabin had not been intact by the various technical and procedural solutions designed to secure explosion [18]. the crew in case of possible launch vehicle failure. Since the first manned spaceflight launches with astronauts onboard had been protected with abort systems. Two basic systems used are solid-fueled rockets and ejection seats which were successfully used on Mercury, Apollo, Soyuz and respectively Vostok, Gemini capsules. Currently developed spacecrafts such as Orion and Dragon v2 will also use solid rocket motors and parachute systems to ensure safety of their crews. The development and missions of the Space Shuttle and Buran orbiters have proven that escape systems mentioned are not practical for such complex designs. Useful solutions in that Figure 1. Intact Crew Cabin after desintegration of The Space matter are yet to be discovered. Shuttle Challenger [17] 2. Launch Failures Statistics Index Terms— Launch Escape Systems, Launch Abort Modes, Crew In order to emphasize the necessity of implementation of Escape Suit, Spaceflight Safety escape systems, especially in the first phases of space launch, exemplary classifications of launch failures is included. It is 1. INTRODUCTION based on categorization of failures relatively to the launch Although the practical usage of large rockets counts more than phase. sixty years and the fundamentals of rocketry have remained the same, today's launch vehicles are still faulty and far from being fully reliable. In the past ten years, approximately 8 % of the all launch attempts ended in a failure. In the history of manned spaceflight, the most disastrous failure occured on January 28, 1986 during the NASA Space Shuttle Challenger launch. 73 seconds into its flight it broke apart which led to the deaths of its seven crew members. It was later determined that the cause of the accident have been the failure of the Challenger's right Solid Rocket Booster O-ring system. Figure 2. Failures according to launch phases [18] www.ijrdt.org | copyright © 2014, All Rights Reserved. 29 Volume-4,Issue-3, Sep-2015 Paper Title:- Ensuring The Safety Of Manned Spacecraft During Launch Phase ISSN (O) :- 2349-3585 lead to landing of the evacuated crew close to the launch area. Any abort system of this kind should cope with results of explosion of the launch vehicle, aerodynamics forces, gravity forces, and impact loads. Abort profile should also consider abort of launch vehicle propulsion system preventing it from explosion, sequencing the crew capsule required to separate from launcher structure, ground or water recovery. Moreover it should ensure the safety of the populated areas in the vicinity. Figure 3. Launch Vehicle Failures - Malfunctioned Subsystems [18] Mode II As can be seen from Figures. 2 and 3 most launch failures occur due to malfunction of propulsion hardware installed in first and Activated in the transition region, which requires rapid entry upper stages of launch vehicle. Such kind of malfunction into the atmosphere. Forces due to possible explosion, various generally results in explosion destroying the whole rocket in a instabilities are generally far less than those occuring in Mode I. matter of seconds. As a consequence shockwave and number of Human factor is important in designing this mode as the crew debris spread in the vicinity of exploding launcher. These must be able to withstand high deceleration loads during reentry. circumstances complicate the task of design of effective launch Spacecraft systems require separating its components from the escape system. ascent vehicle, distancing itself from any explosion damage, 3. LAUNCH ABORT MODES BASED ON NASA jettisoning excess hardware and finally orientating itself to re- PHILOSOPHY entry. Similiar to Mode I, these operations are restricted to low populated areas. In order to design procedures and hardware required for abort systems during launch, ascent of a space vehicle is defined by Mode III three areas [14]: The most critical, in general requires the use of spacecraft Atmospheric - extending from the launch pad to and altitude of propulsion system and atmosheric capabilities for landing. 90,000 m, where the atmosphere has the densest layers, Recovery zones are planned with communication capabilities and the avoidance of populated areas during reentry and landing. Transition - area extended between 90,000 m - 120,000 m, Procedures to avoid collision with jettisoned hardware are which represents the boundary between the Earth's atmosphere included. and outer space, 4. LAUNCH ABORT SYSTEMS Space - beginning at 120,000 m, this is the region where the Designers of manned spacecraft implemented two main systems spacecraft operates and finishes orbit insertion. of crew escape during ascent: escape tower and ejection seats. Up to date (September 2015) the ejection seats have not been Basing on NASA abort philosophy, these areas are used to define employed in any accident. The launch escape tower protection the following abort modes was successfully used during Soyuz 7K-ST No. 16L launch Mode I failure [8]. The escape tower pulled the capsule with astronaut A Mode I abort incorporates all issues related with launch abort away from the exploding booster. The evacuated crew sustained in dense layers of atmosphere. It states that abort system should no injuries and did not require any medical assistance. www.ijrdt.org | copyright © 2014, All Rights Reserved. (30) Volume-4,Issue-3, Sep-2015 Paper Title:- Ensuring The Safety Of Manned Spacecraft During Launch Phase ISSN (O) :- 2349-3585 Escape Tower Ejection seats represents second mode of escape, which has An "escape tower" is a solid (generally) rocket motor been used on two spacecraft programs - Russian Vostok and mounted in a support framework attached to the top of NASA Gemini. A Unique series of both American Space spacecraft. After separation of crew compartment by explosive Shuttle and Russian Buran orbiter featured ejection seats but charges the tower propels the crew away in sitations of such solutions were never progressed to operational use. emergency. Launch escape towers are jettisoned prior to end of Original design of the two-man Gemini spacecraft featured orbit insertion process. They were used on NASA’s Mercury, escape tower but it was rejected in favour of dual ejection seats. Apollo spacecrafts, Russia's Soyuz, Zond vehicles and recently Such solution reduced the total mass of spacecraft significantly by the Chinese Shenzhou vehicle. Modificated design will be [3]. reintroduced for the SpaceX Dragon v2 spacecraft, and designs The Buran space shuttle was to be equipped with ejection such as Orion, Boeing CST-100 capsule. Hardware used on seats for all cosmonauts onboard irrespective of crew size. Apollo and Soyuz spacecrafts are shown on Figures 4 and 5. Buran's ejection seats (K-36RB, K-36M11F35) were standard equipment on Soviet high-performance combat aircraft. he cut- off altitude and speed for the use of K-36RB would have been 30-35 km and Mach 3.0-3.5 respectively. That limit was due to Strizh pressure suit capabilities, especially those related to protection the pilot from the thermal stresses experienced in an ejection. Unique feature of K-36RB was its connection to Buran's computers that ensured the proper seat configuation for one of five available ejection modes corresponding to relevant flight phase [9]. The K-36 ejection seat is presented on Figure 6. Both escape towers and ejection seats expose the crew of Figure 4. Apollo Launch Escape System Tower [5] spacecraft to ejection forces which effects are described on Figure 7. Figure 5. Soyuz Abort System [14] Ejection Seats Figure 6. K-36 RB ejection seat and Strizh pressure suit [9] www.ijrdt.org | copyright © 2014, All Rights Reserved. (31) Volume-4,Issue-3, Sep-2015 Paper Title:- Ensuring The Safety Of Manned Spacecraft During Launch Phase ISSN (O) :- 2349-3585 Figure 7. Injuries occuring during and following ejection [15] 5. CREW PROTECTION Crew protection hardware is represented by full pressure suits. They are worn by Russian astronauts launched onboard Soyuz spacecraft and Space Shuttle crews in all flights after STS-65, for the ascent and entry spaceflight phases. The suit used in Space Shuttle Program is known as Advanced Crew Escape Suit (ACES), manufactured by David Clark Company. It is analogous Figure 8. STS-130 Astronauts wearing ACES [10] to the Russian Sokol suits, yet it has detachable helment and survival backpack. The ACES suit textured gloves design, enables an astronaut to easily access Space Shuttle Control panel, especially the Abort Mode knob and flight control stick during the final approach during landing. Survival backpack includes a personal life raft. During its operational history no ACES has failed. Future Figure 9. Advanced Crew Escape Suit (S1035) specifications [10] improvements may include extended thermal, chemical, pressure Conclusion and windblast protection [10]. The table below illustrates basic Since the first satellite was inserted into an orbit in 1957 specification of ACES pressure suit, which is shown on Figure hundreds of rockets were launched into space and over 500 8. people have visited Earth orbit. However spaceflight still cannot be regarded as a routine and will remain dangerous mean of transport for human explorers in the future. Solutions implemented in non-complex spacecrafts such as Soyuz which is now the only man-rated vehicle can be regarded as reliable. Basing on experience gained throughout decades of space exploration, the design of future spacecrafts such as NASA's www.ijrdt.org | copyright © 2014, All Rights Reserved.