The Challenger shuttle disaster was such a horrifying blow to so many school-age children that two Wyoming students felt they had to do something. They have devised a plan to send money to NASA to build a new shuttle. John McPhillips, 10, and his sister Missy, 9, watched the replays of the explosion in their home town of Gillette, Wyo., as other children did in their home towns across America.

Baffled and saddened by the terrifying accident, John and Missy came up with the idea that the children of United States could do something by sending their dollars to buy a new space shuttle named Challenger VII, in honor of the seven who died. They obviously had no idea that the shuttle originally cost $1.1 billion to build and would cost $2.2 billion to build today, or for that matter just how much a billion dollars is. But then, who does?

Their mother, Karen McPhillips, said she contacted NASA with the idea because she believes this will be psychologically beneficial for children all across the country who need to do something positive to deal with the reality of Tuesday's explosion. NASA spokesman Ken Atchison said yesterday that McPhillips' proposal is one of four separate plans to send money to the space agency. NASA can accept gifts, he explained, but they must be unconditional. NASA can not guarantee how it will spend the money. McPhillips said she raised that problem with a spokesman in former astronaut Sen. John Glenn's office who assured her that there was an 8 percent chance the money going to NASA would help build a new shuttle. That answer satisified her. Tom Wolfe on Test Pilots

In the weeks and months and years yet to come, NASA will be forced to face the question of whether space exploration is really ready for civilians. Tom Wolfe, author of "The Right Stuff," has raised the issue in this week's Newsweek magazine. "Christa McAuliffe was more than the first space passenger," he writes. "Whether she was aware of it or not, wanted to or not, she hurtled for 73 seconds out on the edge of a still-raw technology, then she perished."

Wolfe said he learned while writing his book, later made into a movie, that during the 1970s NASA brass focused on building the shuttle and carefully, outside the glare of publicity, worked at eliminating the grip the original test pilots and fighter pilots had on the agency. That's changed with the accident, Wolfe says. The new question is: "If space flight still involves odds unacceptable to every man, then it should be put back in the hands of those whose profession consists of hanging their hides quite willingly over the yawning red maw." End Notes

There was continual reader concern last week that Duke, the 1960s time warp "Doonesbury" character, was dead. But two readers who wrote to the Personalities column had another theory. Not at all privy to Garry Trudeau's strip appearing today, they referred to a recent article on "zombies" in The Harvard Magazine and predicted Duke's return. It looks as though they're right . . .

Singer Diana Ross and her new husband, Norwegian shipping magnate Arne Naess, left for an undisclosed location on their honeymoon yesterday. The couple were married Saturday in a tiny Swiss village and were the hosts of a lavish reception at a Geneva Lake luxury hotel. Among those attending were singer Stevie Wonder and actor Gregory Peck . . .

It seems evident that not too many members of Jerry Falwell's Moral Majority read People magazine. The publication conducted an unscientific "sin" poll by having readers rate "sins" on a scale of 1 to 10. The obvious ones such as murder, rape, incest and child abuse headed the list in the Feb. 10 issue. Abortion didn't come up until the middle of the list, just ahead of cheating on income taxes and calling in sick when you're not. At the bottom of the list was premarital sex, Jimmy Carter's lust in your heart, masturbation and, last of all, illegal taping off television or radio . . .

Impersonator Rich Little is now doing sex adviser Dr. Ruth Westheimer and in her exuberant voice and style says, "Sex is a lot like politics. You don't have to be good at it to enjoy it" . . .