NASA’s Suomi Satellite: The Suomi National Polar-orbiting Partnership (NPP)

The Suomi National Polar-orbiting Partnership (NPP) mission represents a critical first step in building the next-generation Earth-observing satellite system that will collect data on both long-term climate change and short-term weather conditions. NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense.

NPP will extend and improve upon the Earth system data records established by NASA’s Earth Observing System (EOS) fleet of satellites that have provided critical insights into the dynamics of the entire Earth system: clouds, oceans, vegetation, ice, solid Earth and atmosphere.

The NPP spacecraft lifted off aboard a United Launch Alliance Delta II rocket from Space Launch Complex 2 at Vandenberg Air Force Base in California on Oct. 28, 2011 at 5:48 a.m. EDT.

Image 1: Overnight on October 4-5, 2012, a mass of energetic particles from the atmosphere of the Sun were flung out into space, a phenomenon known as a coronal mass ejection. Three days later, the storm from the Sun stirred up the magnetic field around Earth and produced gorgeous displays of northern lights. NASA satellites track such storms from their origin to their crossing of interplanetary space to their arrival in the atmosphere of Earth.

Using the “day-night band” (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS), the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite acquired this view of the aurora borealis early on the morning of October 8, 2012. The northern lights stretch across Canada’s Quebec and Ontario provinces in the image, and are part of the auroral oval that expanded to middle latitudes because of a geomagnetic storm.

The DNB sensor detects dim light signals such as auroras, airglow, gas flares, city lights, and reflected moonlight. In the case of the image above, the sensor detected the visible light emissions as energetic particles rained down from Earth’s magnetosphere and into the gases of the upper atmosphere. The images are similar to those collected by the Operational Linescan System flown on U.S. Defense Meteorological Satellite Program (DMSP) satellites for the past three decades. “When I first saw images like this as a graduate student, I was immediately struck by the fluid dynamic characteristics of the aurora,” said Tom Moore, a space physicist at NASA’s Goddard Space Flight Center. “Viewing the aurora in this way makes it immediately clear that space weather is an interaction of fluids from the Sun with those of the Earth’s upper atmosphere. The electrodynamics make for important differences between plasmas and ordinary fluids, but familiar behaviors (for example, waves and vortices) are still very apparent. It makes me wonder at the ability of apparently empty space to behave like a fluid.”

Auroras typically occur when solar flares and coronal mass ejections—or even an active solar wind stream—disturb and distort the magnetosphere, the cocoon of space protected by Earth’s magnetic field. The collision of solar particles and pressure into our planet’s magnetosphere accelerates particles trapped in the space around Earth (such as in the radiation belts). Those particles are sent crashing down into Earth’s upper atmosphere—at altitudes of 100 to 400 kilometers (60 to 250 miles)—where they excite oxygen and nitrogen molecules and release photons of light. The results are rays, sheets, and curtains of dancing light in the sky.

Auroras are a beautiful expression of the connection between Sun and Earth, but not all of the connections are benign. Auroras are connected to geomagnetic storms, which can distort radio communications (particularly high frequencies), disrupt electric power systems on the ground, and give slight but detectable doses of radiation to flight crews and passengers on high-latitude airplane flights and on spacecraft.

The advantage of images like those from VIIRS and DMSP is resolution, according to space physicist Patrick Newell of the Johns Hopkins University Applied Physics Laboratory. “You can see very fine detail in the aurora because of the low altitude and the high resolution of the camera,” he said. Most aurora scientists prefer to use images from missions dedicated to aurora studies (such as Polar, IMAGE, and ground-based imagers), which can offer many more images of a storm (rather than one per orbit) and can allow researchers to calculate the energy moving through the atmosphere. There are no science satellites flying right now that provide such a view, though astronauts regularly photograph and film auroras from the International Space Station.

NASA Earth Observatory image by Jesse Allen and Robert Simmon, using VIIRS Day-Night Band data from the Suomi National Polar-orbiting Partnership (Suomi NPP) and the University of Wisconsin’s Community Satellite Processing Package. Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense. Caption by Mike Carlowicz.

Image and caption: NASA Earth Observatory

Image 2: Early on August 28, 2012, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi-NPP satellite captured this nighttime view of Tropical Storm Isaac and the cities near the Gulf Coast of the United States. The image was acquired just after local midnight by the VIIRS “day-night band,” which detects light in a range of wavelengths from green to near-infrared and uses light intensification to enable the detection of dim signals. In this case, the clouds of Isaac were lit by moonlight.

Image: NASA Earth Observatory

Image 3: This image was taken from the VIIRS instrument aboard NASA’s Earth-observing satellite, Suomi NPP. This composite image uses a number of swaths of the Earth’s surface taken on January 4, 2012. The NPP satellite was renamed ‘Suomi NPP’ on January 24, 2012 to honor the late Verner E. Suomi of the University of Wisconsin.

Image and caption: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

Image 4: The new image is a composite of six separate orbits taken on January 23, 2012 by the Suomi National Polar-orbiting Partnership satellite. Both of these new ‘Blue Marble’ images are images taken by a new instrument flying aboard Suomi NPP, the Visible Infrared Imaging Radiometer Suite (VIIRS).

Compiled by NASA Goddard scientist Norman Kuring, this image has the perspective of a viewer looking down from 7,918 miles (about 12,742 kilometers) above the Earth’s surface from a viewpoint of 10 degrees South by 45 degrees East. The four vertical lines of ‘haze’ visible in this image shows the reflection of sunlight off the ocean, or ‘glint,’ that VIIRS captured as it orbited the globe. Suomi NPP is the result of a partnership between NASA, NOAA and the Department of Defense.

Image and Caption: NASA/NOAA

Image 5: Fifteen orbits of the recently launched Suomi NPP satellite provided the VIIRS instrument enough time (and longitude) to gather the pixels for this synthesized view of Earth showing the Arctic, Europe, and Asia.

Image: NASA/GSFC/Suomi NPP

Image 6: The world is currently in an active period for the production of atmospheric aerosols, according to Colin Seftor, an atmospheric physicist at NASA Goddard Space Flight Center in Greenbelt, Md., who compiled this image. Seftor works for Science Systems and Applications, Inc. This image is a combination of a VIIRS RGB image with OMPS aerosol index (AI) data for September 15, 2012.

The OMPS AI shows dust from the Sahara over northern Africa that is being blown over the Atlantic (with yellow, less opaque colors representing less dust and pink, more opaque colors representing more dust). Dust can also be seen over Saudi Arabia and parts of Iran, Afghanistan, and Pakistan. However, the aerosol index signal over the Western U.S. is due to dense smoke from wildfires, while smoke from agricultural biomass burning is visible over both South American and southern Africa. The sun glint in the middle of each swath shows the pattern of the satellite’s view in orbit.

Image: NASA Goddard Space Flight Center

Image 7: A ‘true-color’ image of the Southeastern United States taken on January 19, 2012, the first day the full complement of VIIRS’ 22 channels were active. This images was taken between 5:57 pm USA EST and 6:04 pm USA EST (17:57 - 18:04 UTC).

Suomi NPP is carrying five instruments on board. The biggest and most important instrument is The Visible/Infrared Imager Radiometer Suite or VIIRS.

Image and caption: NASA/Suomi NPP/Atmosphere PEATE/Univ. of Wisconsin-Madison/Liam Gumley

Image 8: From its vantage 824 kilometers (512 miles) above Earth, the Visible Infrared Imager Radiometer Suite (VIIRS) on the NPOESS Preparatory Project (NPP) satellite gets a complete view of our planet every day. This image from November 24, 2011, is the first complete global image from VIIRS.

The NPP satellite launched on October 28, 2011, and VIIRS acquired its first measurements on November 21. To date, the images are preliminary, used to gauge the health of the sensor as engineers continue to power it up for full operation.

Rising from the south and setting in the north on the daylight side of Earth, VIIRS images the surface in long wedges measuring 3,000 kilometers (1,900 miles) across. The swaths from each successive orbit overlap one another, so that at the end of the day, the sensor has a complete view of the globe. The Arctic is missing because it is too dark to view in visible light during the winter.

The NPP satellite was placed in a Sun-synchronous orbit, a unique path that takes the satellite over the equator at the same local (ground) time in every orbit. So, when NPP flies over Kenya, it is about 1:30 p.m. on the ground. When NPP reaches Gabon—about 3,000 kilometers to the west—on the next orbit, it is close to 1:30 p.m. on the ground. This orbit allows the satellite to maintain the same angle between the Earth and the Sun so that all images have similar lighting.

The consistent lighting is evident in the daily global image. Stripes of sunlight (sunglint) reflect off the ocean in the same place on the left side of every swath. The consistent angle is important because it allows scientists to compare images from year to year without worrying about extreme changes in shadows and lighting.

The image also shows a band of haze along the right side of every orbit swath. When light travels through the atmosphere, it bounces off particles or scatters, making the atmosphere look hazy. The scattering effect is most pronounced along the edge of the swath, where the sensor is looking at an angle through more of the atmosphere. Scientists can correct for this scattering effect, but need measurements from a range of wavelengths to do so. The degree to which light scatters depends partly on the wavelength of the light. Blue light scatters more than red light, for example, which is why the sky is blue. VIIRS measures 22 different wavelengths of light, but not all of the sensor’s detectors are operating at peak performance yet. Those measuring thermal infrared light are not yet cold enough to collect reliable measurements.

Once VIIRS begins full operations, it will produce a range of measurements from ocean temperature to clouds to the locations of fires. These measurements will help extend the record from earlier sensors like the Moderate Resolution Imaging Spectroradiometer (MODIS). VIIRS is very similar to MODIS, but flies at a higher altitude to measure the whole planet without gaps. (MODIS daily measurements have gaps at the equator. See the MODIS image from November 24.) VIIRS also sees the Earth in less detail, 375 meters per pixel, compared to 250 meters per pixel for MODIS.

Image: NASA Earth Observatory

(Source: Wired)