| On a recent (April 19-May 2, 1999) trip to the
Arctic, personnel from NASA's Goddard Space Flight Center chose the
North Pole as the unique site from which to demonstrate how new
communications technologies and the Internet now make it possible for
scientists working in very remote locations to send and receive data
using NASA communications satellites. Accompanied by nine other
engineers, scientists, and outreach personnel (also from NASA's GSFC),
we traveled to Resolute Bay and Eureka, Canada, before heading north to
the "top of the world" to broadcast the first ever live webcast from the
North Pole. We had two main objectives on this expedition: (1) to
demonstrate the new communications technologies that made our live
webcasts possible, and (2) to take measurements of various aspects of
the Arctic environment.
What is most unique about this expedition is
that students from around the world participated in some of our
scientific activities via their personal computers. This "virtual field
trip" involved the exchange of dialogue from their computers while
hearing responses to their questions as they watched live video
demonstrations by the expedition team.
|Communications and Science
During the expedition, we demonstrated three new communications instruments that scientists can use while conducting field experiments: TILT (TDRS Internet Link Terminal), ECOMM (Early Communications), and PORTCOMM (Portable Communications). Each of these new instruments has design advantages and disadvantages. For instance, the TILT system transmits a high-quality signal appropriate for television or World Wide Web broadcasts at the relatively high rate of 1 megabit per second. The ECOMM system also transmits a television and Web broadcast quality signal, but at the much slower rate of 128 kilobits per second. However, at a fraction of the weight of TILT and consuming only one-third the power, ECOMM is much easier to transport for webcasts from remote locations. The PORTCOMM system yields an added communications capability while on the move. While moving in a car, a helicopter, and even a dogsled, we were able to send data files at a rate of 4.8 kilobits per second (again, much slower than the previous system).
All three communication packages were developed at GSFC and use NASA's Tracking and Data Relay Satellite-1 (TDRS-1) to complete the communication links. Launched in 1983, TDRS-1 is currently in a geosynchronous orbit (an orbit in which the orbital velocity of the satellite matches the spin rate of the Earth) that is inclined sufficiently to make it visible to the polar regions of the globe four hours each day, with a maximum elevation of 1.6 degrees above the horizon.
In addition to the communications element, and as an integral component of the expedition, scientific observations and measurements were made. The team collected ozone measurements with a hand-held Microtops photometer provided by Gordon Labow of GSFC Code 916 and Global Positioning System (GPS) measurements with a Trimble GPS Unit provided by Steve Cohen and Erricos Pavlis of GSFC Code 921. Sea ice thickness measurements were made through holes drilled with both powered and manual ice augers. The ozone measurements will be compared with satellite observations made by NASA's Total Ozone Mapping Spectrometer (TOMS), as checks on both the Microtops and the satellite data. The GPS measurements from Resolute Bay will be used, in conjunction with additional measurements after several years, to examine glacial rebound, i.e., the uplifting of the land surface in response to the removal of the weight of the Pleistocene ice sheet.
The GPS measurements from the North Pole will be compared with corresponding measurements taken concurrently at the South Pole and in equatorial locations, to allow students to quantify easily the polar flattening of the Earth, i.e., the fact that the distance from the North Pole to the South Pole is less than the equatorial diameter of the Earth. The sea ice thickness measurements are being compared with other Arctic ice thickness measurements made from the surface and from submarines (sonar data). In addition, soil samples were collected, air temperatures were measured, and cloud type and cloud cover observations were recorded in conjunction with the protocols set forth by the Global Learning and Observations to Benefit the Environment (GLOBE) program and Elissa Levine of GSFC Code 923. These measurements added a new location for the global atmospheric and soil measuring efforts of the GLOBE program, as students worldwide will compare our data with data from their local schools.