Leadership in Space

I read Jim Albaugh’s article with interest [“Reaffirming U.S. Leadership in Space,” Commentary, May 26, page 19]. Mr. Albaugh is absolutely correct: “Propulsion is the great enabler.” He says: “We must reduce the cost and increase the efficiency of space propulsion.” I couldn’t agree more. I have written several letters on exactly this subject.

He also mentions the “only one large liquid propulsion engine developed (recently) in this country – RS-
This is unfortunate. The RS-68 should not have been built. It is the most inefficient engine we have developed. It claims a specific impulse of 408 seconds compared with a specific impulse of 448 seconds for the J-2 engine, and 455 seconds for the space shuttle main engines.

Why on Earth have we developed an engine significantly less efficient than state of the art operating engines? This is not trivial. The consequences are that the Ares vehicle will have to be significantly larger than necessary to carry the excessive fuel load. The excess fuel will cost more, and the larger structure, necessary to carry the excess fuel, will cost more. Because the vehicle is larger than necessary it will have more aerodynamic drag and will carry much less payload than it should. It will carry a lesser payload at greater cost. That is a losing proposition for the tax paying public. Contrary to Mr. Albaugh’s call to “support the current policy,” I think we should have a different policy. The policy should be to develop advanced performance rocket engines before we return to the Moon or venture to Mars.

Dale L. Jensen

Lawndale, Calif