EOM April 2005 > SHARING IN GEOTECHNOLOGIES

Continued


No, this is not an artist's rendition. It is the northern lights over Svalbard, Norway, which is a prime location for the reception of satellite data and imagery in the northern latitudes. Solar storms sometimes cause shimmering, often colorful lights called auroras to appear in the night skies. Auroras usually appear in the northern latitudes but occasionally can be seen from points further south. Photo courtesy: B. Hillestad, Kongsberg Satellite Services (KSAT).

NPOESS Space Environmental Sensor Suite
So what is being done to mitigate the effects of space weather? NPOESS is at the forefront, among the many space-based and ground-based sensors currently deployed and being developed. NPOESS will advance near-Earth space environmental sensing capabilities and deliver critical observations to space weather forecasters in NOAA and the USAF faster than ever before. New technologies from the research community will be incorporated into NPOESS under a program for Pre-Planned Product Improvement (P3I). NPOESS will provide improved operational capabilities beyond those currently available from the Department of Defense's (DoD) Defense Meteorological Satellite Program (DMSP) and NOAA's Polar-orbiting Operational Environmental Satellite (POES) systems that NPOESS will replace.

NPOESS will expand the ranges and sensitivities of the DMSP and POES sensors for monitoring the near-Earth space environment. Currently, DMSP and POES satellites measure the space environment in the vicinity of the spacecraft using a variety of sensor technologies. An ionospheric cold plasma sensor, auroral ion and electron spectrometers, and a magnetometer are deployed on each DMSP spacecraft. Sensors aboard NOAA's POES spacecraft measure the differential flux of ions and electrons over a wide energy range.

DMSP also carries ultraviolet (UV) remote sensing instruments for broad-area observations of charged and neutral particle densities within the atmosphere. Instruments comprising the Space Environmental Sensor Suite (SESS) will be included in each of the three NPOESS orbits. These evenly spaced, sun-synchronous orbits will provide global coverage every four hours, with increased spatial and temporal resolution that will provide significant improvements over current capabilities.

An intense aurora over Norway and Sweden on October 30, 2003 as seen from the Defense Meteorological Satellite, which will be replaced by NPOESS in 2009. Space weather observation is an important role for NPOESS as key parts of our nation's infrastructure are vulnerable to solar storms.

Within the space environment, the NPOESS SESS will provide measurements needed to satisfy user requirements for 11 Environmental Data Records (EDRs), including specifications of the ionosphere and neutral atmosphere, measurements of energetic charged particles, and the morphology of the high-latitude aurora. Similar to the instruments on DMSP and POES, the SESS will rely on a combination of in-situ and remote sensing techniques to measure the assigned set of space environment EDRs:

• The Thermal Plasma Sensor (TPS) will monitor the temperature, density, and motion of the local ionosphere at the 828-km altitude of the NPOESS satellite.
• A complement of particle detectors will measure the flux and energy of charged particle precipitation into the atmosphere along magnetic field lines that trace to distant space.
• Precipitating charged particles ranging in energy from 30 electron volts (eV) to over 100 million eV will be measured within three distinct energy bands by the Low Energy Particle Sensor (LEPS), the Medium Energy Particle Sensor (MEPS), and the High Energy Particle Sensor (HEPS).
• Remote optical imagery of UV emissions measured by the UV-Limb/Disk Imager will be used to determine the density profiles of the ionosphere and thermosphere.
• UV-Limb/Disk Imager data with supporting measurements from the NPOESS Visible/Infrared Imager Radiometer Suite (VIIRS) will be used to measure the auroral energy-deposition rates. When fused with ancillary data from other NPOESS sensors, the space environmental measurements from SESS will better meet user needs for near-Earth space environmental data.

NPOESS is also seeking innovative approaches to address other space environment EDRs, such as measuring the geomagnetic field using data from other, more suitable, spacecraft and employing the NPOESS infrastructure to bring these observations to users.

A revolutionary improvement in data retrieval is planned for NPOESS. The SafetyNet ground data receptor network will enable users to receive and process NPOESS environmental data in less than 28 minutes from the moment it was captured for 95 percent of the data, compared to about two hours for the DMSP and POES systems. Considering that space environmental conditions can vary on time scales of tens of minutes, SafetyNet will allow space weather service providers to better support time-critical operations and space- based resource protection.

Preparing For The Future
Although the NPOESS space environment sensors will be quite capable, there is a need for improved measurements. In fact, thanks in part to the active participation of the future NPOESS users, planned NPOESS SESS capabilities have already improved some 40 percent over the original design. The developers of NPOESS are keenly aware that even the best sensors are of little use unless the science is adequate to yield efficient and reliable algorithms to convert raw data into useable environmental products. To this end, the NPOESS prime contractor (Northrop Grumman Space Technology), the NPOESS Integrated Program Office (IPO), and the scientific community participate in Operational Algorithm Teams (OATs).

The DMSP energetic particle sensor (SSJ5), which is the heritage sensor for the NPOESS LEPS (Low Energy Particle Sensor)

The NPOESS P3I program, previously discussed, will also address shortfalls in meeting user needs, including requirements for measuring ionospheric scintillation. Ionospheric scintillation is among the military's top space weather concerns due to the potential degradation of Ultra High Frequency (UHF) communications and Global Positioning System (GPS) navigation. The NPOESS IPO is working closely with the user community, the research community, and industry to insert the latest capabilities into NPOESS to meet validated user needs.

NPOESS will carry on a long legacy of operational space-based measurements of the space environment. As the civilian and military sectors continue to expand their reliance on space it will become imperative that our monitoring, analysis, and forecasting tools for space weather improve to meet our increased needs.

NPOESS will become a key component of our national strategy for space weather. The active involvement of the user community is critical to NPOESS and will allow the program to meet near- term operational requirements and be poised to meet future needs. When it comes to space weather, what appears to be science fiction today will be science fact of tomorrow. A developing space weather monitor-and- alert system will indeed help us to live a safer and more efficient life on planet Earth.

Fountains of multimillion-degree, electrified gas in the atmosphere of the Sun have revealed the location where the solar atmosphere is heated to temperatures 300 times greater than the Sun's visible surface. Image from NASA TRACE (Transition Region and Coronal Explorer) spacecraft

NPOESS capabilities to sense the space environment will benefit numerous communities — in particular industry, the military, the communications sector, and the public. NPOESS terrestrial weather observations will bring great advantages to the rest of society as well. In the next article in this series we'll explore how NPOESS will help feed and further protect the passengers of "spaceship earth."

About the Authors
Lt. Col. Mike Bonadonna is the U.S. Air Force User Liaison for the NPOESS Integrated Program Office and can be reached at [email protected].
Dr. William Denig is a research physicist with the U.S. Air Force Research Laboratory, Space Vehicles Directorate, Hanscom Air Force Base, Massachusetts. His areas of expertise are Space Weather and the effects of the space environment on military/civilian systems. He can be reached at [email protected].
Dave Jones is Founder, President, and CEO of StormCenter Communications, Inc. (stormcenter.com). He is also President of the Foundation for Earth Science and sits on the Executive Committee of the Federation of Earth Science Information Partners (ESIP Federation).

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