Research Stories

by Robert Burnham

Question: What weighs 2,600 pounds, would fill a Smart Car to overflowing, and comes from all over the world?

Answer: 10,000 rocks.

Yes, the 10,000th piece of planet Earth arrived at Arizona State University earlier this summer. The bits and pieces and chunks of rock were all contributed by members of the general public as part of ASU’s Rock Around the World (RATW) program.

The landmark rock is a fist-size piece of weathered quartz collected from the bed of the Manumati River, west of Kathmandu, Nepal. It was sent by Mahesh K., a 17-year-old student at Xavier Academy in Kathmandu.

RATW10000 joins 9,999 others sent to the Mars Space Flight Facility on ASU's Tempe campus since the Rock Around the World program began in January 2004.

The rocks were collected by adults, schoolchildren, and all ages in between. They come from 80 countries (and counting). Every continent is represented, including Antarctica (RATW06896). To see where the rocks have come from, visit the RATW site at http://ratw.asu.edu.

“Day after day, I'm amazed by the variety that arrives in the mail,” says RATW founder Philip Christensen. He is the director of the Mars Space Flight Facility and Regents' Professor of geological sciences in the School of Earth and Space Exploration, part of the College of Liberal Arts and Sciences.

“And they're not just from school kids, either. We've gotten rocks from people in their 90s—and from future geologists less than a year old.”

RATW10000 (center) as it was found in the Manumati River, near Kathmandu, Nepal. Photo by Mahesh K.

Words trigger an avalanche
Christensen is the principal investigator for the Miniature Thermal Emission Spectrometer (Mini-TES), a mineral-scouting camera mounted on each of NASA's two Mars Exploration Rovers, Spirit and Opportunity. The rovers landed in January 2004.

During a televised NASA press conference at the time of the rover landings, Christensen made a casual comment that kicked off the Rock Around the World program, almost as an afterthought.

“I mentioned that I had once gone to Iceland to collect rocks, and I had traveled 14 hours to get there,” Christensen recalls. “But when I arrived, I saw a school right across the road from the rocks I was collecting. It struck me that I could have just asked those kids to send me a rock from their school!”

Broadcast worldwide on NASA TV, that comment was enough to start the avalanche.

By the time Christensen got back to campus after the initial rover landing activities, the first rocks had started to arrive. Dozens of rocks followed. Then hundreds of rocks. Then still more. Amid the growing piles of mailbags and boxes—heavy mailbags and boxes—the Rock Around the World program was born.

“The campus mail service wasn't exactly thrilled with us,” says Christensen. Soon, though, the arrival of rocks in the mail became routine. The average now runs 50 to 100 rocks a month.

The Mars Space Flight Facility has one of the world's largest libraries of infrared mineral spectra. Many thousands of sample spectra are made available to scientists. Every rock sent to the Rock Around the World program has its infrared spectrum taken and added to the online library.

“Coming from all over the world, the rocks people send have great scientific interest,” says Christensen. “No one could afford to go out and collect so many rocks from so many places.” And, he adds, while these are all Earth rocks, they're also useful in extraterrestrial ways.

“The Mini-TES instruments on the rovers take infrared spectra of Martian rocks near the rovers,” says Christensen. “The science team compares the Mini-TES spectra with laboratory spectra of terrestrial rocks and minerals. This lets us pick out the best Mars rocks for closer study by the rovers.”

Rock shop
When the donated rocks arrive at the Mars Space Flight Facility, they land in the hands of Theresa Rogers. She coordinates the program and is in charge of the student workers who actually process the rocks.

“As each rock is received,” she says, “we give it a 5-digit ID number, clean it if necessary, photograph it alongside a ruler, and prepare it to be analyzed by the infrared spectrometer.”

Rogers joined the program soon after it began. Her daughter Laurie was one of the original RATW staff members. She called her mom for help as the growing volume of submitted rocks threatened to become unmanageable.

On arrival, each rock is placed in a separate plastic bag, along with whatever documentation the sender supplies. This usually includes photos, copies of maps, and the sample's latitude and longitude as derived from GPS or Google Earth.

Rogers explains the process. “The night before each rock is analyzed it spends eight hours in an oven. This cooks off any moisture inside,” she says. “It also helps the spectrometer give more accurate readings.”

After processing, the numbered rocks are archived permanently in a special storage space. The space is built to preserve the rocks and make them available for access by scientists as needed.

rock 10k2

RATW10K: Himalayan souvenir
RATW10000 is both ordinary and unusual, says Steven Ruff, a research mineralogist at the Mars Space Flight Facility.

“The spectrum is that of nearly pure quartz,” he says. “That makes this rock unremarkable with regard to mineralogy. But it does have a notable texture. It’s pockmarked with many indentations and holes.”

As Ruff explains, “The quartz probably crystallized from hot, silica-rich fluids moving through fractures in pre-existing rock. The texture could come from other minerals that crystallized before or during the quartz crystallization but then dissolved later, leaving the voids.”

There are traces of the original host rock still embedded in the quartz, he says. “Given that this rock came from a riverbed in the vicinity of the Himalayas, I'm speculating that it represents the product of hot fluids produced during the intense metamorphism associated with the mountain building.”

Earthlings: Please send us your rocks
Got an old rock in need of a new home? Find something interesting on your travels and want to share it with geoscientists the world over?

The RATW Web site has directions on how big a sample to collect, what to include when you send it, and where you should send it to. Everyone who submits a rock receives a frameable certificate with the rock's number, printed in color and signed by Philip Christensen.

“Whether you have a rock or a mineral, and regardless of where it came from, we're interested in seeing it,” the ASU scientist adds.