[parsifal]

I am all for throwing money at this particular problem. parsy.

[r9etb]

Just as the scientific community predicted, the financial shortfalls of the ISS have forced NASA to shift funds from unmanned missions that have a far greater chance of yielding important discoveries

Out of all those words, this is the real crux of the story. As usual, the JPL guys want to spend all of that money on their poorly managed and over-budget programs, and Scientific American is helping them along.

[boris]

"But such a craft would have to carry 10 times its weight in fuel"

Interesting accomplishment. If only it were true in this universe.

Think about it. If it carries 10 times its own weight in fuel, then it would weigh 11 times what it weighs!

What he means to say is 10 times its inert weight.

In other words, its "lambda-p" has to be > 0.90. The correct formula is:

Lambda-p (propellant fraction) = (weight of propellant)/(weight of propellant+weight of inerts)

Also, rockets carry fuel and oxidizer. We are very specific. When speaking of the combination of these chemicals, we use the word, propellants; fuel plus oxidizer = propellants.

--Boris