A Symbol: An in-space ballerina and hypersonic flying marvel, the Space Shuttle Orbiter is almost impossible for others to duplicate and continues to generate international admiration and respect for U.S. technical capabilities.
Full Potential Not Yet Realised: The multi-functional Orbiter has performed "as designed" on all assignments including reentry and a key role in the International Space Station (ISS) assembly. Like any new manned system, as crews and engineers become more familiar (like a helicopter) performance "in the box" improves and extending-the-box opportunities are identified. So far the Orbiter has operated generally within the box.
Too Young For Retirement: Each remaining Orbiter has many missions and years of life remaining. The Orbiter was designed for a one hundred mission life with a factor of four (i.e. 400 flight potential). It has experienced low flight rates and has not been structurally overloaded (maximum loads occur during the boost phase and high wind shear situations have been avoided through pre-flight meteorological observations) and receives a complete examination and any necessary refurbishment between each flight.
The System is Safe for Continued Man Flights: No critical failures have originated from within the triply redundant Orbiter itself but like any spacecraft designed for light-weight, it is vulnerable to abuse (e.g. SRB O rings, ET insulation debris); these are now known and addressable problems.
The Space Shuttle Main Engines (SSME)s were a principal safety concern through the development years but their flight record has been excellent and it may be that the integrity of recovered, refurbished rocket engines is as good as or even better than new ones. Some rocket engine incipient failures may lie undetected in ocean graves.
Real Usability Through "Landing With Dignity": Turnaround man hours are costly for the Orbiter, not the least demanding being the heat shield preparation and changes are continually being made to improve the situation. Even so, this relatively light-weight, first generation radiant heat shield is itself reusable and obviates having to pay for a new vehicle and other ancillary costs such as ocean recovery for every flight. Note: In depth reviews of "flown" Apollo command modules concluded that second flights of the hardware would be too costly at that time.
New Space Initiatives Depend On The Orbiter For Identification and Pursuit: The on-orbit assembly option for a deep space manned system became more viable upon completion of the International Space Station (ISS) using the Orbiter. An "Orbiter" segment of a deep space system would be used in assembly activities, on-orbit transfers, tug functions and most importantly for the crew Earth-to-orbit and orbit-to-Earth transfer.
Reliance on an Orbiter for re-entry would eliminate configuration constraints on size and shape and the weight of items such as parachutes, heat shields and landing impact structure and the energy needed to transport this otherwise useless added weight throughout the entire deep space mission.
This approach essentially would trade-off these advantages against the development of an additional propulsion module for return from deep space to high/low Earth orbit. The present Orbiter would be a key mechanism in the early development of such an on-orbit assembled system.
The Shuttle Continues to Be An Intriguing Candidate For "Commercialisation": The system is presently operational. Its payload-to-orbit delivery and other capabilities are well documented. Its risks are known and assessable for payload insurance and crew-safety considerations and industrial elements are already doing much of the work in many areas.
Bailing, leasing and/or other type of agreement for use of government equipment (Orbiters, pads, control centers, etc.) is probably feasible in some arrangement. Needed is an industry, NASA-government, Congressional meeting of the minds on all related elements including government flight requirements, (e.g. ISS servicing) and commercial pricing policies.
If such a government hand-off to industry could be affected it would, of course, keep the Shuttle Program available for another decade or two should presently unforeseen government needs arise (even today it would be most helpful to have Apollo supply and rescue vehicles that serviced Skylab available for use on the ISS).
U. S. Taxpayers Have Not Yet Realised Their Full Return-on-Investment (ROI) From the Shuttle System:
+ It really works; it is not just a briefing chart promise.
+ It has much life remaining and could be the key to the identification and development of new systems.
+ It is man-rated and safe--probably as safe as any manned system will be-no others will get over one hundred flights down the learning curve.
+ The infrastructure is in place and operational and has provided industry through extensive, hands-on participation with the depth of training necessary to assume total system accountability.
+ To replace the Orbiter capabilities will take decades and billions.
Decommissioning the Space Shuttle should be postponed indefinitely.
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