CONCORD, N.H. (AP) — In October 1961, Gus Grissom glumly confided to his mother in a letter that is now up for auction that he and his fellow Mercury 7 astronauts resented John Glenn after he was picked to be the first American to orbit the Earth.

Within the famously competitive group, Glenn had emerged as the face of the space program, while Grissom was reticent in front of the press. When he wrote to his mother, Grissom was still stinging from his Liberty Bell 7 flight on July 21, 1961, that ended with a blown hatch, a sunken space capsule and accusations that the former Air Force fighter pilot had panicked.

"The flight crew for the orbital mission has been picked and I’m not on it," he writes in slanting script, each line of blue ink climbing slightly from left to right on the Project Mercury letterhead. "Of course I’ve been feeling pretty low for the past few days. All of us are mad because Glenn was picked. But we expressed our views prior to the selection so there isn’t much we can do about it but support the flight and the program."

The letter is being auctioned online by RR Auction of Amherst, N.H., which got it from Grissom’s brother, Lowell.

"Those original seven Mercury astronauts were extremely competitive people," Lowell Grissom said this week. "If one was picked over another, they all thought it should be them. It’s that kind of atmosphere; they all wanted to be first."

Virgil "Gus" Grissom was the second American to make a suborbital flight. After splashing down in the Atlantic Ocean, his craft sank when the hatch blew open prematurely and it filled with water. Grissom narrowly escaped drowning and insisted until his death in a 1967 Apollo launch pad fire that he did nothing to cause the hatch to blow.

Glenn became the first American to orbit Earth in February 1962 and is the last surviving Mercury 7 astronaut. He did not return calls seeking comment.

In the Oct. 7 letter to his mother Cecile, Grissom candidly shares his disappointment at being named a flight controller for the second orbital flight, to be piloted by Donald "Deke" Slayton. (Slayton was replaced by Scott Carpenter because of a heart condition.)

"It’s not a job I want," Grissom writes. "I have to do a great deal of the work, I’ll be gone from home a lot and I don’t get any of the credit, but if anything goes wrong, I’ll get a good deal of the blame."

Grissom would later pilot the Gemini III orbital mission.

There’s a touch of mystery, too. Before he shares the flight crew information — which he cautions his mother to "keep it under your hat" — Grissom drops a hint that someone may be listening in.

"I probably would call you, because it’s been so long since I’ve called or written, but I’ve got some news I don’t think I should talk about over the phone," he writes.

Bobby Livingston, executive vice president of RR Auction, said the letter offers rare insight into the mind of a driven, talented man. He expects it could fetch $80,000 when the auction closes on Thursday; a letter from Alan Shepherd to his parents about trying out for the space program sold for $106,000.

Lowell Grissom said the letter reveals a side of his brother away from the space program. He writes that his wife, Betty, is "getting pretty fed up" with him being away from home so much, and interrupts the letter midway through to take the family bowling.

"I kind of think that it shows that he was just a normal kind of guy; that he had deep involvement in the space program but also had a family to take care of," he said.

The letter had been sitting in a drawer and Lowell Grissom said he was selling it to "keep Gus’ memory alive and let people know what kind of man he was."