SPACECRAFT : COST & OPERATIONS

SPACECRAFT : COST & OPERATIONS:

Retrospect Costs:

While the Shuttle has been a reasonably successful launch vehicle, it has not met the goal of greatly reducing launch costs. There are various ways to measure per-launch costs. One way is dividing the total cost over the life of the program (including buildings, facilities, training, salaries, etc) by the number of launches. This method gives about $1.3 billion per launch[1]. Another method is calculating the incremental (or marginal) cost differential to add or subtract one flight — just the immediate resources expended/saved involved in that one flight. This is about $55 million. Neither figure is right or wrong; they are simply different ways to examine the picture.

The total cost of the program has been $145 billion as of early 2005, and is estimated to be $174 billion when the Shuttle retires in 2010. NASA's budget for 2005 allocates 30%, or $5 billion, to Space Shuttle operations.

Although the final design differs from the original concept, the project was still supposed to meet USAF goals and be much cheaper to fly in general. One reason behind this apparent failure is inflation. During the 1970s the U.S. suffered from severe inflation. Between when the program began in 1972, and first flight in April 1981, inflation increased prices over 200%. When evaluating shuttle development costs in later-year dollars, this superficially appeared to be a large cost overrun in the program. In fact when discounting inflation, the shuttle development program was within the initial cost estimate given to President Richard M. Nixon in 1971.

Some reasons for higher than expected operational costs can be ascribed to:

Maintenance of thermal protection tiles turned out to be very labour intensive, averaging about 1 person·week to replace a tile, with hundreds damaged with each launch. 

The main engines were highly complex and maintenance intensive, necessitating removal and extensive inspection after each flight. Before the current "Block II" engines, the turbopumps (a primary engine component) had to be removed, dissembled, and totally overhauled after each flight. 

Launch rate is significantly lower than initially expected. This does not reduce actual
Launch rate is significantly lower than initially expected. This does not reduce actual operating costs, but if dividing total program costs by number of launches, more launches per year produces a lower per-launch cost figure. Some early hypothetical studies examined 55 launches per year, but the maximum possible launch rate was limited to 24 per year, based on manufacturing capacity of the external tank. Early in the shuttle development, the expected launch rate was about 12 per year. Launch rates reached 9 per year in 1985 but averaged less thereafter. 

Early cost estimates of $118 per pound of payload were based on marginal or incremental launch costs, and based on 1972 dollars and assuming a 65,000 pound payload capacity. Correcting for inflation and other factors, this equates to roughly $36 million incremental costs per launch. Compared to this, today's actual incremental per launch costs are about 50% more, or $55 million per launch. 

Shuttle operations:

The Shuttle was originally conceived to operate somewhat like an airliner. After landing, the orbiter would be checked out and start "mating" to the rest of the system (the ET and SRBs), and be ready for launch in as little as two weeks. Instead, this turnaround process takes months; Columbia was once launched twice within 56 days. Because loss of crew is unacceptable, the primary focus of the Shuttle program is to return the crew to Earth safely, which can conflict with other goals, namely to launch payloads cheaply. Furthermore, because in some cases there are no survivable abort modes, many pieces of hardware simply must function perfectly and so must be carefully inspected before each flight. The result is high labour cost, with around 25,000 workers in Shuttle operations and labour costs of about $1 billon per year.
 

NASA's plan for using the shuttle to launch all unmanned payloads declined, then was discontinued. Following the Challenger disaster, carrying in the shuttle payload bay the powerful liquid fuelled Centaur upper stages planed for interplanetary probes was ruled out. The Shuttle's history of unexpected delays also makes it liable to miss narrow launch windows. Advances in technology over the last decade have made probes smaller and lighter, and as a result unmanned probes and communications satellites can use cheaper and more reliable expendable rockets, including Delta launcher, and Atlas V.