He knew exactly what he wanted to do when he joined the Navy after graduating from Fallbrook High School in 1998. He wanted to be a Navy SEAL.
In high school, he had been active in the Mormon Church and Boy Scouts. A former teacher remembered him as polite, disciplined, a bit of a risk-taker. SEAL posters adorned his bedroom.
The son of a doctor, Carter graduated from boot camp at Great Lakes, Ill., and then Basic Underwater Demolition/SEAL training in Coronado, Calif. More than half of SEAL students drop out, but not Carter, a stocky 5-foot-5 and outdoor athlete who loved physical challenges.
Once he was in the SEALs, his rise through the ranks was swift. He deployed during the U.S. campaign to topple the Taliban in Afghanistan and then during the early stages of the U.S. mission in Iraq.
His fellow SEALs gave him the nickname Badger after the small but ferocious animal. The name was bestowed after Carter beat a 6-foot-5 opponent in a wrestling match.
Two months ago, Carter got word that he had been promoted to chief petty officer. He e-mailed his friends about his excitement at getting promoted and being part of a SEAL team involved in missions aimed at thwarting the insurgency in Iraq.
The same friends got an e-mail or phone call recently telling them that Carter, 27, had been killed in combat Dec. 11 on an undisclosed mission in Iraq.
Although he had spent much of his career with West Coast SEAL teams, Carter was part of an East Coast team based at Little Creek Naval Amphibious Base in Norfolk, Va., when he was killed.
The facts behind his death and earlier service in Afghanistan and Iraq may never be fully known. Like other special forces units, the SEALs keep a tight hold on their identities and the facts behind their missions. His parents, Cindy and Dr. Thomas Carter, now of Council Bluffs, Iowa, have declined to speak to the media.
Although SEALs do multiple tasks, one of Carter's specialties was keeping team members in radio contact during missions. When team members cannot communicate with each other, high-risk missions can go awry.
"Without a good comm guy, you can't complete a mission," said Petty Officer 1st Class Steve Otten, who teaches at the SEALs school and will soon leave active duty. "Next to the officer in charge, the comm guy is probably the most important. Mark was one of the best."
Carter's funeral last week at Arlington National Cemetery was heavily attended by Navy officers and enlisted sailors, many with the security clearance necessary to know the details about his death and prior deployments. At the service, Carter's family received his third Bronze Star for valor.
Among the speakers was an ensign who went through boot camp and SEALs training with Carter. He praised Carter as the "embodiment of the warrior ethos." In an interview, the ensign remembered Carter's upbeat attitude. "You'd be in the ocean and very, very cold, and then look over at Mark," said the ensign, who began his career in the enlisted ranks. "He'd be grinning and laughing."
Off-duty, Carter enjoyed rock climbing, mountaineering, diving and shooting. He was not married. "He dedicated his life to being the best SEAL he could be," the ensign said.
SEAL teams from Coronado were in Afghanistan and then in Iraq before the assault by conventional troops. In Iraq, SEALs searched for biological weapon storehouses, helped direct airstrikes and mapped the routes used by Army and Marine convoys in their race to Baghdad.
In Iraq, Carter was part of a sniper team. "He was the kind of guy who was determined to be the first to kick down a door," said a fellow sniper, a SEAL who asked to be identified only as Eddie.
Another SEAL, a senior chief petty officer, said that when he had the chance to pick the members of his platoon, Carter was his first choice.
"There were dozens and dozens of guys, but Mark was the best," the senior chief said. "He had a contagious personality. He always found the sunny skies in the grayest of days."
Although the SEALs, like other military units, have suffered casualties in Iraq and Afghanistan, the loss of Carter has been particularly painful, the SEALs said.
"You hate to see the space Mark occupied go vacant," the senior chief said.