UCAR > Communications > Staff Notes > August 1995 Search

HAO Scientist Adapts to Climate Change

With the budget ax whirring in Washington, dollars for science dwindling, and the ever-present need for accurate, comprehensive measurements not letting up, scientists are getting terribly creative. Tom Woods of the High Altitude Observatory (HAO), for example, is involved in two experiments with tiny budgets and potentially big payoffs.

In one, he's taken his extreme ultraviolet (EUV) spectrograph and photometer off a sounding rocket and put them on a satellite with 12 other instruments. In the other, he is co-investigator for a small satellite to be designed, built, and operated by University of Colorado students to measure nitric oxide and solar x-rays.

Tom Woods and the SEE team gather around the shiny payload at its going-away party last spring. In front are Clarke Chambellan (left) and Ron Lull. From left to right (standing) are Paul Willis, Terry Leach, Greg Ucker, Kim Streander, Tom, Ray Wrigley, Howard Hull, Chris Pankratz, and Paula Rubin.

A bird in the hand . . .
When NASA's Marshall Space Flight Center first called Tom about the Multiple Experiment Transporter to Earth Orbit and Return (METEOR) project, he recalls, "There was a lot of head shaking, mostly horizontal." Building a satellite instrument in two months seemed impossible. But "when I considered the scientific benefit of having a couple of years of daily solar EUV irradiance measurements versus five minutes per year from our existing sounding rocket program, I changed my mind."

To help things along, the data-gathering instruments already existed. Tom had been rocket-launching an EUV spectrograph and soft x-ray photometer every year from White Sands Missile Range in New Mexico. Still, a few things had to be taken care of in the project's two- month prep time. Engineer Greg Ucker made a special packaging to house the instruments on the spacecraft. Greg Card, Howard Hull, Terry Leach, and Ron Lull designed, built, and tested the electronic interface for the commercial microprocessor Tom had located in a week. Ray Wrigley and Chris Pankratz conducted thermal vacuum tests at CU, followed by vibration tests at Ball Aerospace. Meanwhile Ray and Paula Rubin designed and built the ground support equipment. And that was it--with a week to spare.

Called the Solar Extreme Ultraviolet Experiment (SEE), Tom's project was originally planned as part of NASA's elaborate Thermosphere, Ionosphere, and Mesosphere: Energy and Dynamics mission to study the upper atmosphere. TIMED's budget had already been scaled back several times and could still die before the satellite's 1999 launch date.

Meanwhile, from the METEOR orbit 400 kilometers above the earth, the EUV spectrograph will measure the extreme ultraviolet wavelengths of the solar spectrum from 25 to 120 nanometers (nm) at 0.2 resolution. The photometer will cover 1 to 40 nm in a chunk of 10 nm at a time. Although its resolution is coarser than the spectrograph's, the photometer degrades more slowly, so its measurements remain accurate over a longer period. Besides, the spectrograph planned to measure the lowest wavelengths for TIMED wasn't ready for a transplant to METEOR.

Scientists need to place their instruments high up to measure EUV because it is absorbed in the upper atmosphere, never reaching the earth's surface. Short and wild, these wavelengths bring enormous energy into the earth system. They can push temperatures in the upper atmosphere several hundred degrees from day to night and up to 1,000íC over the course of the sun's 11-year cycle. These drastic swings in heating and cooling diminish as solar energy journeys down through the layers of our atmosphere, but the sun still powers the climate we experience at the surface.

Only when scientists have succeeded in accurately measuring both short-term fluctuations and long-term trends in solar input will they be able to separate the sun's natural effects on climate from warming caused by human activities. Toward this goal, the SEE data will provide a far more comprehensive and accurate picture than the measurements from the 1970s currently relied on by solar-terrestrial researchers.

If it all works, that is
"Our instrument works fine," says Tom, "but the spacecraft itself has 30 to 40 components, so a lot could go wrong." Even scarier, the rocket is brand-new. Designed by EER Systems of McLean, Virginia, to carry midsize satellites into space, the Conestoga rocket will be making its very first voyage when it launches SEE later this month from Wallops Island, Virginia. EER operates a commercial launch facility there, not far from NASA's. (At press time, the launch date was uncertain.)

NASA is funding 7 of the 13 experiments, including SEE. The other six are commercial payloads, with several from Motorola. In its current incarnation, SEE's total budget is a slim $250,000 for this fiscal year.

"This opportunity is literally once-in-a-lifetime," Tom says. If it crashes, there won't be a second chance. "In the old days, they made back-ups for backups. Now NASA builds less expensive, faster missions with no redundancy. Failure rate is up, but cost is down."

The instrument will open its door and begin gathering data three weeks after the launch. CTA Space Systems, which integrated the instruments on the satellite and prepared it for flight, will also operate the control center in McLean. Twice daily they will forward about 100 kilobytes of data to Tom over E-mail.

"It's a high-risk mission on an unproven spacecraft and rocket. But if it works, the benefits would exceed all our expectations for the near future. I'm willing to take that gamble."

SNOE: Student power lowers costs
A new way of doing things is also in hand at CU. There Tom is co- investigator in the Student Nitric Oxide Experiment (SNOE), funded through NASA's Student Explorer Demonstration Initiative. STEDI was designed to assess the potential of smaller, low-cost space flight missions with large student involvement. A mere $4.4 million covers the entire mission, except the launch vehicle and launch services.

CU undergraduate and graduate students will work on the project under faculty guidance at CU's Laboratory for Atmospheric and Space Physics (LASP), with additional help from Ball Aerospace engineers and Tom. A computer drafting class from Arapahoe High School in Littleton will also participate. "The idea here is to excite and educate the next generation of aerospace professionals," comments deputy principal investigator Stan Solomon of LASP. Charles Barth, also of LASP, is principal investigator.

The student experiment will study how nitric oxide in the middle and upper atmosphere responds to variations in the solar energy input. Nitric oxide plays a key role in the energy balance of the thermosphere and ionosphere. At lower altitudes, it can destroy ozone. The relevant energy input is from solar soft x-rays and auroral energetic electrons. To measure the soft x-rays, Tom and others in the instrument group at HAO will help the students build a set of soft x-ray photometers similar to the one used in SEE.

"The SNOE program is an outstanding opportunity for students to contribute to a real science project instead of the typical textbook laboratory experiment," says Tom. "Consequently, the students' enthusiasm and quality of work have both been extremely high."

Scheduled for a March 1997 launch, SNOE is expected to orbit the earth for at least a year. It will be launched on a Pegasus rocket by Orbital Sciences Corporation, who put UNAVCO's GPS/MET satellite into space last spring. SNOE is one of two experiments selected from 66 applications by the Universities Space Research Association, which is administering the STEDI program for NASA. --Anatta

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Edited by Bob Henson, bhenson@ucar.edu
Last revised: Wed Mar 29 17:33:36 MST 2000