Tag Archives: Launch and Orbital Mechanics

Requiem for the Space Shuttle

The shuttle transportation was, by any reasonable standard, one of the most complicated engineering projects in the long history of science and technology.  But, as it was implemented, it never made much economic sense.  In part, this disappointing outcome, came about because its payload was too big and heavy to achieve reliable and cost-effective operation.

Why was the shuttle payload so big and heavy?

The shuttle payload was originally baselined at 65,000 pounds.  It never actually carried that much weight: the heaviest payload it ever flew into space was around 50,000 ponds.  But, as a practical matter, even that lighter payload was much too heavy.  Military users insisted on heavy-life capabilities because they wanted to use the shuttle transportation system to launch their big, heavy spy satellites into space.


In my view, a 15,000-pound payload weight would have been a more practical selection.  With a correspondingly lighter orbiter, those troublesome thermal tiles would have been unnecessary.  And the booster could have been towed (using Kevlar cables) from the shuttle landing strip at Cape Canaveral by 747 airplanes up to a 40,000-foot attitude with a release velocity of about 600 miles per hour.


Unmanned cargo missions using the amazingly inexpensive Russian Soyuz booster – or an American equivalent – could have carried heavy components into low-altitude earth orbits at much more affordable prices.

As Figure 1 indicates, the Russians offered to sell the Americans Soyuz missions with 15,400-pound payloads for $12 million each.  On such a mission, the delivery cost for each pound of payload would have been only $780, or about 1/6th the comparable cost of the American Delta II booster.  In my opinion, we should have bought 1000 Soyuz boosters. Instead, we put severe restrictions on the use for boosting American satellites into space.


In my view we lost a golden opportunity.  But, actually, chemical rockets – Soyuz, Delta II, the shuttle transportation system – are the problem, not the solution.  So what is the alternative?


Satellites Without Rockets

As I have often told my students in my “Launch and Orbital Mechanics” short courses:  “There is nothing wrong with the space program that the elimination of chemical rockets wouldn’t cure.” Chemical rockets are dirty, dangerous, fragile, unreliable, and horribly expensive.


A simple mathematic derivation shows that a typical multistage rocket of modern design wastes about 97-percent of its energy accelerating propellants it’s going to burn later.  If cars were similarly inefficient, few people would want to own one.


Is there a better way to launch payload into space?  In my 4-day short courses on “Launch and Orbital Mechanics”, held at key locations around the country, I list and discuss 30 alternatives to chemical rockets.  These include solar electric propulsion, laser-powered rockets, maglev boosters, nuclear powered rockets, tethered satellites, and skyhooks (space elevators).  These alternatives, implemented in the proper combination, could revolutionize the way future generations conduct large-scale operations and do business in space.


What If the Space Shuttle Engineers Had Designed My Car?

Many times, over the years, I have taught at Vandenberg Air Force Base in California where satellites are launched into near polar orbits.  Vandenberg is 175 miles from my home in Seal Beach, California.  It is one of the few short-course locations I drive to in my car.  Mostly I fly to the various locations where the courses are offered.


A few years ago, I was driving back home from Vandenberg Air Force Base when an interesting question occurred to me:  “What would my car be like if the engineers who designed the space shuttle orbiter had designed it?

When I got back to Seal Beach, I kludged together Figure 2.  Study its contents to see how incredibly inefficient the shuttle transportation system turned out to be. Notice, for example, that only 1 percent of the lift-off weight of the shuttle transportation system is useful payload that ends up being left in space.  If my car had been designed with similar payload-carrying capabilities, it would be able to deliver only one 21-pound briefcase to Vandenberg or any other destination 175 miles away.


Expendable rockets are not much more efficient.  On a typical mission only about 2.5 to 3.0 percent of their lift-off weight is useful payload.  Isn’t it becoming abundantly clear why there’s nothing wrong with the space program that the elimination of chemical rockets wouldn’t cure?”



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