Hundreds of trees have been to the Moon. How they got there and back again is a curious tale.

by Dr Tony Phillips

Scattered around our planet are hundreds of living things that have been to the Moon and back again. None of them are human. They outnumber active astronauts 3:1. And most are missing.

They're trees. "Moon Trees."

NASA scientist Dave Williams has found 40 of them and he's looking for more. "They were just seeds when they left Earth in 1971 onboard Apollo 14," explains Williams. "Now they're fully grown. They look like ordinary trees - but they're special because they've been to the Moon."

How they got there and back is a curious tale.

It begins in 1953 when Stuart Roosa parachuted into an Oregon forest fire. He had just taken a summer job as a US Forest Service "smoke jumper," parachuting into wildfires in order to put them out. It was probably adventure that first attracted Roosa to the job, but he soon grew to love the forests, too. "My father had an affinity for the outdoors," recalls Air Force Lt. Col. Jack Roosa, Stuart's son. "He often reminisced about the tall Ponderosa pine trees from his smoke jumping days."

Thirteen years later, NASA invited Roosa, who had since become an Air Force test pilot, to join the astronaut program. He accepted. Roosa, Ed Mitchell and Al Shepard eventually formed the prime crew for Apollo 14, slated for launch in 1971.

"Each Apollo astronaut was allowed to take a small number of personal items to the Moon," continued Jack. Their PPKs, or Personal Preference Kits, were often filled with trinkets - coins, stamps or mission patches. Al Shepard took golf balls. On Gemini 3, John Young brought a corned beef sandwich. "My father chose trees," says Jack. "It was his way of paying tribute to the US Forest Service."

The Forest Service was delighted.

"It was part science, part publicity stunt," laughs Stan Krugman, who was the US Forest Service's staff director for forest genetics research in 1971. "The scientists wanted to find out what would happen to these seeds if they took a ride to the Moon. Would they sprout? Would the trees look normal?" In those days biologists had done few experiments in space; this would be one of the first. "We also wanted to give them away as part of the Bicentennial celebration in 1976."

Stuart Roosa, Apollo 14 command module pilot, in 1971.

Krugman himself selected the varieties: Redwood, Loblolly pine, Sycamore, Douglas Fir and Sweetgum. "I picked redwoods because they were well-known, and the others because they would grow well in many parts of the United States," he explained. "The seeds came from two Forest Service genetics institutes. In most cases we knew their parents (a key requirement for any post-flight genetic studies)."

On January 31, 1971, Apollo 14 blasted off. Only Shepard and Mitchell actually walked on the Moon. On Feb. 5th they landed the lunar module Antares in Fra Mauro - a hilly area where Shepard famously launched his golf balls using a geology tool as a makeshift driver. Roosa remained in orbit as pilot of the mission's command module Kitty Hawk. Inside his PPK was a metal cylinder, 6 inches long and 3 inches wide, filled with seeds. Together they circled the Moon 34 times.

Apollo 14 was a success. Scientists were delighted with the mission's geology experiments and they were eager to study the 43 kg of Moon rocks collected by Shepard and Mitchell. Krugman was just as eager to study the seeds.

"We had a bit of a scare," Krugman recalls. During decontamination procedures, the seed canister was exposed to vacuum and it burst. The seeds were scattered and traumatized. "We weren't sure if they were still viable," he says. Working by hand, Krugman carefully separated the seeds by species and sent them to Forest Service labs in Mississippi and California. Despite the accident, nearly all of them germinated. "We had [hundreds of] seedlings that had been to the Moon!" Thirty-one years later, Krugman still sounds excited.

During the years that followed, the trees thrived as scientists watched. "The trees grew normally," he continued. "They reproduced with Earth trees and their offspring, called half-Moon trees, were normal, too." (He notes, however, that DNA analysis wasn't routinely done in the early '70's, and so the Moon trees weren't tested in that way. There might be subtle differences yet to be discovered.)

A Moon tree at the NASA Goddard Space Flight Centre.

Finally, in 1975, they were ready to leave the lab. "That's when things got out of hand," he says.

Everyone wanted a Moon tree. In 1975 and '76, trees were sent to the White House, to Independence Square in Philadelphia, to Valley Forge. "One tree went to the Emperor of Japan. Senators wanted trees to dedicate buildings. We even did some plantings in New Orleans because the mayor there, Mayor Moon, wanted some," says Krugman. There were so many requests that "we had to produce additional seedlings from rooted cuttings of the original trees."

No one kept systematic records, notes Dave Williams. That's why the whereabouts of the trees today are mostly unknown.

One of the them went to a Girl Scout camp in Cannelton, Indiana, where 3rd grade teacher Joan Goble found it in 1996. (She knew it was a Moon Tree because a sign said so. Most Moon trees were planted with ceremony; there's usually a sign or plaque nearby that identifies them.) "My students love it," she says. "It looks like an ordinary tree, but they feel it's special anyway because of its trip to the Moon." Jack Roosa has since become a pen pal of Goble's class, encouraging the students to explore and learn as his father did.

When Goble contacted Dave Williams to ask for more information about Moon trees, "I was clueless," Williams admits. Like many people who were young in the 1970's, Williams had never heard of such trees, but he soon became an enthusiast. "I found one Moon tree right here at Goddard near my office," he laughs. "I had no idea it was there."

Often that's how they're encountered - by accident. Williams now maintains a web site listing all known Moon trees. If you stumble across one then contact him. He'll investigate the find and add it to the collection if it's authentic.

more Students in Goble's 3rd grade class made this sign for their Moon tree in Indiana.

Moon trees are long-lived, adds Krugman. The redwoods could last thousands of years, and the pines have a life expectancy of centuries. Indeed, they've already outlived Stuart Roosa and Al Shepard - two of the humans who took them to the Moon.