I must take issue with Louis Friedman’s letter “Mars Cannot Wait,” [Aug. 22, page 18 ].

We have focused too much on payloads at the expense of launch vehicle development. We have used the Delta 2 as a crutch for too long — and the miserable failure of the Demonstration Approach and Rendezvous Technology program and the Defense Advanced Research Projects Agency Challenge show how backwards robotic missions are. We have lost five out of 17 Mars missions, causing me to question Friedman’s statement about how you usually “do better” with robotics.

We only see the two [Mars Exploration Rovers] up there as a success because they are very lucky. With the recent Volna [solar sail] flopnik, Mr. Friedman learned the hard way that if you focus on science payloads while ignoring an interest in launch vehicles, you get burned. Mars, in fact, can wait. It isn’t going anywhere.

But if we keep nickel and diming ourselves to death with those Delta 2 rockets, and the space shuttle and international space station , neither will NASA. It is time to focus on big boosters and not little toys.

Jeff Wright, Pinson, Ala.