Shuttle Flight Paths and Its Risk - Essay Example

In the United s, NASA provides all oversight on the Space Transportation System (STS), encompassing 'intergovernmental agency requirements and international and joint projects, and the launch and space flight requirements for civilian and commercial use' (NASA). NASA shuttle systems are comprised of four elements: 1) an orbiter spacecraft; 2) dual Solid Rocket Boosters (SRB); 3) an external fuel tank for oxidizer; 4) and three Space Shuttle main engines. Reuse of the tank and boosters is a critical. The shuttle is launched in an upright position by thrust of the engines and the two SRB. In an approximately a two minute time interval, the two boosters are spent and are separated from the external tank. Once spent, they fall into the ocean at predetermined points and are recovered for reuse. After about eight minutes firing of the engines shuts down, and the craft is injected into orbit. At this time, the external tank is then separated from the orbiter, and is sent into a ballistic trajectory in a designated, yet remote area of the ocean, and is not intended for recuperation. The engine system is constituted of thirty eight primary Reaction Control System (RCS) engines and six vernier RCS engines. RCS are used for maneuvering leverage. Reaction control system release of the engines is done in sequential separation from the orbiter. Initiation of the Orbital Maneuvering System (OMS) engines fires the orbiter into orbit. OMS are used to increase velocity on the orbiter's maneuvers. Two OMS execute the orbiter into orbit, while only one thrust sequence is utilized for deorbit. Velocity is attained at approximately 25, 405 feet per second (17,322 statute miles per hour). Deorbit requires a decrease of velocity at about 300 fps (205 mph) for reentry. In the initial entry sequence, the RCS engines control the attitude (i.e. pitch, roll and yaw) of the orbiter, as aerodynamic pressure builds toward activation of the primary reaction control system engine inhibitors. High temperatures induced by entry, are mitigated by a reusable thermal protection system over the entire orbiter. Once unpowered, the orbiter glides to Earth and lands with aviation instrumentation with nominal touchdown at 186 to 196 knots of speed (i.e. 213 to 213 to 225 miles per hour. Risk assessment and cost mitigation management planning in the space community is prefaced by the prediction that satellites have disasters of their own. On February 24, 2009, orbit of the OCO satellite failed as it was being carried into space when the Taurus rocket carrying the craft detached and crashed into the sea near Antarctica. Initial launch of the Observatory was followed by reschedule of the project. In terms of statistical significance probabilistic risk projections of satellite failure and especially satellite collisions are almost impossible to predict. In consideration of the primary differences between accident risk and other types of risk such as public health mitigation of toxicological risk are located in: 1) the derivative of hazard utility to cost; 2) and longitudinal repercussions of consequences of risk. Accidents, while potentially easier to evaluate and hence, mitigate according to engineering systems analysis, may include environmental disasters unknown or statistically insignificant (i.e. outer space satellite collisions). Costs may be high due to level of technological process included in such systemic models of risk accountability, but potential for adherence to regulatory expectation is high in professional settings where scientific analysis and expert operation of technological endeavors eliminates random human errors by laypersons. Here the garbage in and garbage out scenario works best, as garbage can be understood and controlled through incorporation of monitoring into mitigation strategies. A schematic showing the arrangement of the valves in the main propulsion system of Mars Observer (Harland, 2005). The development of universal Safety and Hazard Analysis sources by NASA and their impact on manufacturing illustrates the circular logistics within the risk management feedback loop in aerospace engineering science, and reveals quite a bit about the relation between production flow analysis of technical suppliers to scientific agencies, and management of their finance and regulatory oversight. Utilization of technical product systems under hazard spec provision (i.e. statute limitations on use) by NASA on experimental projects, points to the regulatory restrictions on potential engineering solutions once a particular chemical (e.g. flourine gas) has been determined illegal. Modification of projects according to "severity classification" that those hazards are identified to present at any time in the analysis (preliminary to system hazard), will slow a mission. The Safety Checklist on the NASA LIDAR experiment informs NPOESS at the arctic ozone hole, and the Hazard and Operability (HAZOP) Study systematic group approach both offer front end solutions to potential problems. HAZOP is "a qualitative method of analysis used in identifying risk related to highly hazardous substances. The method provides a means of identifying a multitude of process hazards. It is used to identify potential hazards and operability problems early in the acquisition cycle at the time of design development of a process." The application of the HAZOP method to potential failures is designed to identify collective deviations which would greatly impact cost. Another qualitative analysis method, Energy Trace Barrier Analysis (ETBA) offers a more detailed knowledge of hazards by tracing the flows of energy throughout a facility, system or operation. The premise for this methodology is mishaps: 1) from the risks within an operation; 2) interrupt or degrade the operation; and 3) are an unwanted transfer of energy - and may produce injury to persons or property due to a lack of barriers or controls over the energy. The System Hazard Analysis (SHA) and Subsystem Hazard Analysis (SSHA) are designed to perform assessment of hazards in sub-systems. The SHA examines the interfaces between subsystems, and integrates the outputs of the SSHA. Subsystems analyses are typically specifications in a procurement spec guide, and completed by the equipment/subsystem manufacturer. Again, a front end assessment, the SHA and SSHA include engineering schematics and specifications, and address potential component and equipment failures or faults, and human errors that establish a hazard due to the functional failures. A parallel response may be factored into the manufacturer relationship prior to receipt. For instance, the Active Risk Manager and in the SAPHIRE risk assessment tool used by Northrup Grumman on the NASA JPL missions screen sub-systems products with: significant Risk Lists, assignment of risk ratings, and preparation of mitigation plans. Example of participation by commercial partners on NASA JPL's Screening Committee is reflected in Northrop Grumman's contribution to the JPL Lessons Learned Committee which is responsible for drafting most JPL LL submitted to the NASA Lessons Learned system. Fault tree analysis (FTA) are also employed by NASA, and is an analytical technique that enables targeted issues in the state of the system as specified (usually a state that is critical from a safety standpoint) to be found and analyzed 'in the context of its environment and operation to find all credible ways in which the undesired event can occur.' FTA offer' a model representation for the interpretation of a limited set of parallel and sequential combinations in faults that may result in convergence during a predefined event. Often referred to as a 'gate-way' analysis, FTA do not serve as models of all possible system failures or all possible causes of system failure. A FTA is not an exhaustive classification of faults, and is tailored to its top event and corresponds to some particular system failure mode; thus incorporating only faults that contribute to a designated top event. Fault tree of possible causes of the repeated momentum dumps by the NEAR spacecraft after it aborted its burn. Certain events result from AND-ing or OR-ing other events (Failure Report) (Harland, 2005). In David Harland's (2005) Space Systems Failures: Disasters and Rescues of Satellites, he discusses the types of priority risk within space engineering, and reviews the most failures most consistently tested within satellite and space probe launch Citing redundancies, common failures include complications in the: propulsion system; attitude control system (i.e. Gyros); electrical system - component, communications, electromagnetic interference or instrument; environmental failures - electrostatic discharge, impact, space, solar and radiation; structural failures - mechanism or thermal; and on the ground - construction, hazardous environment or testing; operator or software errors. Although some degree of failure is random, says Harland, where there is little in terms of 'empirical support' so too there is likelihood of failure. Preliminary risk planning 'against development time and cost' is best supported by utilization of a metric for assessment. Planned schedule duration as seen in the 'Complexity Index' for researched assessment of factors such as spacecraft power, pointing accuracy and type of propulsion by The Aerospace Corporation of El Segundo, California. Complexity Index, The Aerospace Corporation. The introduction of the Zero Gravity, Zero Tax Bill to the United States Congress July of 2001 set the stage for legislative policy on space-oriented enterprises with the amendment of the Internal Revenue Code of 1986 to provide tax incentives for investing in companies involved in space-related activities. The provision allows for income investment credits to fund new enterprises in this area, and augmentation of those incentives for established company's already engaged in space related activities. Other aspects of the Act resulted in capital gains exclusions and 10 year tax exclusion on gross income. Zero-G, Zero-T 'is intended to create an enterprise zone in orbit' (Rohrbacher 2002). For suppliers to National Aeronautics and Space Administration (NASA), the Act incited renewed interest in partnership with the Agency's $15 billion budget. Once the province of the few due to the high cost of risk within space - and especially launch with its complex, multi-scale risk assessment, and disaster mitigation planning, logistics and material expense - space-based companies were presented with a range of profitable rather money-losing contract incentives. Bibliography Bahr, N.J., 1997. System Safety Engineering and Risk Assessment: A Practical Approach. New York: Taylor & Francis. Harland, D.M. and Lorenz, R., 2005. Space Systems Failures: Disasters and Rescues of Satellites, Rockets and Space Probes. Dordrecht: Springer. How Space Shuttles Work, 2010 . Howstuffworks. Available: http://www.howstuffworks.com/space-shuttle.htm/printable [5/7/2010, 2010]. National Polar-Orbiting Operational Environment Satellite System (NPOESS), 2010. Northrup Grumman. Available at: http://www.as.northropgrumman.com/products/npoess/index.html NASA Facility Systems Safety Guidebook. Available at: http://www.hq.nasa.gov/office/codeq/87197c-6.pdf NASA-STD-8719.7, Chapter 7: Other Hazard Analysis Methodologies, January 1998. NASA. Available at: http://www.hq.nasa.gov/office/codeq/871977-c.pdf NASA Jet Propulsion Laboratory, Orbiting Carbon Observatory. Available at: http://oco.jpl.nasa.gov/ Aeronautics and Space Engineering Board (ASEB). Available at: http://www.nap.edu/openbook.phprecord_id=10616&page=40 Risk Models: Cost Risk, Schedule Risk, Risk Management. The Aerospace Corporation. Available at: (Cost Risk): http://www.aero.org/education/tai/documents/CostRiskQuickRef.pdf Schedule Risk : http://www.aero.org/education/tai/documents/ScheduleRiskQuickRef.pdf Risk Management: http://www.aero.org/education/tai/documents/RiskMgtQuickRef.pdf Rep. Rohrabacher, 2001. H.R. 2504 Zero Gravity, Zero Tax Act of 2001 (Introduced in the House). 107th United States Congress, 1st Session, H. R. 2504, Monday, July 16, 2001. Space Ref.com. Available at: http://www.spaceref.com/news/viewsr.htmlpid=3240 2002. Zero Gravity, Zero Tax. In: Hudgins, Edward L. ed., 2002. Space: The Free Market Frontier. Washington D.C.: The Cato Institute, pp. 213-214. SAPHIRE. Northrup Grumman. Available at: https://saphire.inel.gov/guest_area/FACETS_Vol-4_No-2.pdf Space Transportation System. NASA. Available at: http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_overview.html [5/7/2010, 2010]. Read More