How the Deep Space Climate Observatory satellite is taking Earth’s ultimate selfie
On July 6, a new satellite sent the first photo of Earth’s entire sunlit face since the famous “Blue Marble” shot taken by Apollo 17 astronauts in 1972. All other “photos” since 1972 have been several images stitched together. The Deep Space Climate Observatory (DSCOVR) can capture new images every other hour because it is locked in a spot a million miles above the Earth. But DSCOVR isn’t just up there to make pretty pictures, and it certainly isn’t alone.
Images taken
July 6
Taken July 16
Moon
Gravitational pulls of the Earth and sun hold DSCOVR in place at Lagrange Point 1.
Drawing is schematic.
L1
Earth
Sun
SATELLITE ORBIT RANGES
Earth
Lagrange Point 1
1
2
3
4
1
LOW EARTH ORBIT
11 miles to 1,250 miles from Earth
669 satellites
Most Earth images are taken at this relatively close range. Some satellites take images of the same place at the same time each day to monitor changes.
2
MID-EARTH ORBIT
1,250 miles to 22,200 miles from Earth
94 satellites
This distance works well for navigation and communications satellites that monitor specific areas. It’s too far away for satellites whose primary function is taking images of Earth.
3
HIGH EARTH ORBIT
Above 22,000 miles from Earth
465 satellites
High Earth orbit begins roughly a tenth of the way to the moon. Satellites that reach 22,300 miles above sea level hit a sweet spot called geostationary orbit in which they travel at the same speed as the Earth's rotation, so they stay in place over the equator. Many weather and communications satellites operate in this area.
4
LAGRANGE POINT 1
1,000,000 miles from Earth
DSCOVR is positioned in a sweet spot between Earth and the sun, called Lagrange Point 1, where competing gravity fields hold it in place. This gives DSCOVR a constant, unobstructed view of the sun. Only a handful of satellites are positioned at this point or beyond.
While Earth selfies may be the DSCOVR satellite’s neatest party trick, its main purpose is to observe the sun. The product of NASA, NOAA and the U.S. Air Force was launched in February to monitor space weather and provide early warning of solar storms that might wreak havoc with satellites, communication systems
and Earth’s power grid.
DSCOVR
What are
satellites doing?
Of the 1,265 satellites that were in orbit as of Jan. 31, more than 300 are primarily observing — and taking images of — Earth. Most are there for other reasons, mainly communications. The oldest satellite still operating is a U.S. amateur radio satellite that had a three-year life expectancy when it was launched in 1974.
Primary purpose
Communications
Earth observation
Technology
Navigation
Space science,
research and
observation
660
309
135
95
66
Their users
Commercial
Government
Military
Civil
479
356
346
84
Origins
United States
China
Russia
Other
528
132
131
474
Launch year for
active satellites
As of Jan. 31
160
1
4
’74
’78
’88
’15
Satellite counts are as of Jan. 31,
the month before DSCOVR was launched.
Alternate views
of Earth
Not all satellites that monitor Earth create images using the spectrum of light that humans can see. Many produce other types of images for specific purposes. Some examples, provided by the Committee on Earth Observation Satellites (CEOS):
THERMAL
An aerial photo of this 2013 wildfire in Australia would show only smoke, but this image tracks the fire using its heat signature.
Landsat-7
U.S. Geological Survey
USGS via CEOS
INFRARED
Another type of image from the same satellite detects vegetation cover (in red), defining the extent to which the fire had burned the area.
Landsat-7
U.S. Geological Survey
USGS via CEOS
RADAR
Radar can penetrate cloud cover to monitor changes in Earth’s surface features such as amounts of sea ice, snow cover and vegetation. The left image of Mount Fuji on a cloudy day shows what our eyes would see. The one on the right was produced using radar.
Landsat-8
U.S. Geological Survey
USGS via CEOS
ALOS-2
Japan Aerospace Exploration Agency
Japan Aerospace Exploration Agency via CEOS
SPOTLIGHT
Spotlight imaging mode shows extremely detailed portions of relatively small sections at a time. A two-satellite team captured this high-resolution image of Hamilton Island over the Great Barrier Reef. These satellites cross the equator at the same local time each day, making the angle of sunlight consistent for comparisons over time.
Pléiades HR1 A and B
Centre National d’Études Spatiales (CNES) — France
Copyright 2015 CNES/Distribution AIRBUS DS Via CEOS
COMPOSITE
Data from images taken over the same location over a long period can be combined to show cyclical patterns or to detect changes over time. The small images below are among hundreds of images used to create the composite at bottom, which showed the dropping water supply in rural Menindee Lakes, Australia, between 2000 and 2007.
Landsat-7
U.S. Geological Survey
Images by USGS; composite image by Geoscience Australia via CEOS
Images taken
July 6
Taken July 16
Moon
Gravitational pulls of the Earth and sun hold DSCOVR in place at Lagrange Point 1.
Earth
L1
Sun
92.96 million miles
from Earth
Drawing is schematic.
LAGRANGE POINT 1
1,000,000 miles from Earth
DSCOVR is positioned in a sweet spot between Earth and the sun, called Lagrange Point 1, where competing gravity fields hold it in place. This gives DSCOVR a constant, unobstructed view of the sun. Only a handful of satellites are positioned at this point or beyond.
DSCOVR
1,000,000
DSCOVR
While Earth selfies may be the DSCOVR satellite’s neatest party trick, its main purpose is to observe the sun. The product of NASA, NOAA and the U.S. Air Force was launched in February to monitor space weather and provide early warning of solar storms that might wreak havoc with satellites, communication systems and Earth’s power grid.
The Moon orbits about
240,000 miles from Earth
HIGH EARTH ORBIT
Above 22,200 miles from Earth
High Earth orbit begins roughly a tenth of the way to the moon. Satellites that reach 22,300 miles above sea level hit a sweet spot called geostationary orbit in which they travel at the same speed as the Earth's rotation, so they stay in place over the equator. Many weather and communications satellites operate in this area.
50,000
465 satellites
40,000
30,000
MID-EARTH ORBIT
1,250 miles to 22,200 miles from Earth
This distance works well for navigation and communications satellites that monitor specific areas. It’s too far away for satellites whose primary function is taking images of Earth.
20,000
94 satellites
LOW EARTH ORBIT
10,000
11 miles to 1,250 miles from Earth
Most Earth images are taken at this relatively close range. Some satellites take images over the same location at the same time each day to monitor changes.
669 satellites
Satellite counts are as of Jan. 31, the month before DSCOVR was launched.
What are satellites doing?
Of the 1,265 satellites that were in orbit as of Jan. 31, more than 300 are primarily observing — and taking images of — Earth. Most are there for other reasons, mainly communications. The oldest satellite still operating is a U.S. amateur radio satellite that had a three-year life expectancy when it was launched in 1974.
Primary purpose
160
Their users
Communications
Earth observation
Technology
Navigation
Space science, research and observation
660
Commercial
Government
Military
Civil
479
309
356
135
346
95
84
66
Launch year for
active satellites
As of Jan. 31
Origins
United States
China
Russia
Other
528
132
4
131
1
’74
’78
’88
’15
474
Satellite counts are as of Jan. 31, the month before DSCOVR was launched.
Alternate views of Earth
Not all satellites that monitor Earth create images using the spectrum of light that humans can see. Many produce other types of images for specific purposes. Some examples, provided by the Committee on Earth Observation Satellites (CEOS):
THERMAL
INFRARED
An aerial photo of this 2013 wildfire in Australia would show only smoke, but this image tracks the fire using its heat signature.
Another type of image from the same satellite detects vegetation cover (in red), defining the extent to which the fire had burned the area..
Landsat-7
U.S. Geological Survey
Landsat-7
U.S. Geological Survey
USGS via CEOS
USGS via CEOS
RADAR
Radar can penetrate cloud cover to monitor changes in Earth’s surface features such as amounts of sea ice, snow cover and vegetation. The left image of Mount Fuji on a cloudy day shows what our eyes would see. The one on the right was produced using radar.
Landsat-8
U.S. Geological Survey
ALOS-2
Japan Aerospace Exploration Agency
USGS via CEOS
Japan Aerospace Exploration Agency via CEOS
SPOTLIGHT
Spotlight imaging mode shows extremely detailed portions of relatively small sections at a time. A two-satellite team captured this high-resolution image of Hamilton Island over the Great Barrier Reef. These satellites cross the equator at the same local time each day, making the angle of sunlight consistent for comparisons over time.
Pléiades HR1 A and B
Centre National d’Études Spatiales (CNES) — France
Copyright 2015 CNES/Distribution AIRBUS DS Via CEOS
COMPOSITE
Data from images taken over the same location over a long period can be combined to show cyclical patterns or to detect changes over time. The small images below are among hundreds of images used to create the composite at bottom, which showed the dropping water supply in rural Menindee Lakes, Australia, between 2000 and 2007.
Landsat-7
U.S. Geological Survey
Images by USGS; composite image by Geoscience Australia via CEOS
July 6
Taken July 16
Images taken
July 6
Moon
Gravitational pulls of the Earth and sun hold DSCOVR in place at Lagrange Point 1.
Drawing is schematic.
While Earth selfies may be the DSCOVR satellite’s neatest party trick, its main purpose is to observe the sun. The product of NASA, NOAA and the U.S. Air Force was launched in February to monitor space weather and provide early warning of solar storms that might wreak havoc with satellites, communication systems and Earth’s power grid.
L1
Earth
This side
faces the
sun
The EPIC
imager
faces Earth
Sun
92.96 million miles
from Earth
1,000,000
50,000
40,000
30,000
20,000
10,000
1,250
DSCOVR
Moon
LAGRANGE POINT 1
HIGH EARTH ORBIT
MID-EARTH ORBIT
LOW EARTH ORBIT
240,000
miles
11 miles to
1,250 miles
1,000,000 miles from Earth.
Above 22,000 miles
1,250 miles to
22,200 miles
94 satellites
669 satellites
465 satellites
DSCOVR is positioned in a sweet spot between Earth and the sun, called Lagrange Point 1, where competing gravity fields hold it in place. This gives DSCOVR a constant, unobstructed view of the sun. Only a handful of satellites are positioned at this point or beyond
High Earth orbit begins roughly a tenth of the way to the moon. Satellites that reach 22,300 miles above sea level hit a sweet spot called geostationary orbit in which they travel at the same speed the Earth's rotation, so they stay in place over the equator. Many weather and communications satellites operate in this area.
This distance works well for navigation and communications satellites that monitor specific areas. It’s too far away for satellites whose primary function is taking images of Earth.
Most Earth images are taken at this relatively close range. Some satellites take images of the same place at the same time each day to monitor changes.
Satellite counts are as of Jan. 31, 2015, the month before DSCOVR was launched.
What are
satellites doing?
Of the 1,265 satellites that were in orbit as of Jan. 31, more than 300 are primarily observing — and taking images of — Earth. Most are there for other reasons, mainly communications. The oldest satellite still operating is a U.S. amateur radio satellite that had a three-year life expectancy when it was launched in 1974.
160
Origins
Launch year
for active satellites
As of Jan. 31
Primary purpose
Their users
United States
China
Russia
Other
Communications
Earth observation
Technology
Navigation
Space science,
research and observation
528
Commercial
Government
Military
Civil
479
660
132
356
309
135
131
346
1
4
95
474
84
’74
’78
’88
’15
66
Satellite counts are as of Jan. 31, the month before DSCOVR was launched.
Alternate
views of Earth
Not all satellites that monitor Earth create images using the spectrum of light that humans can see. Many produce other types of images for specific purposes. Some examples, provided by the Committee on Earth Observation Satellites (CEOS):
RADAR
THERMAL
INFRARED
Radar can penetrate cloud cover to monitor changes in Earth’s surface features such as amounts of sea ice, snow cover and vegetation. The left image of Mount Fuji on a cloudy day shows what our eyes would see. The one on the right was produced using radar.
An aerial photo of this 2013 wildfire in Australia would show only smoke, but this image tracks the fire using its heat signature.
Another type of image from the same satellite detects vegetation cover (in red), defining the extent to which the fire had burned the area.
ALOS-2
Japan Aerospace Exploration Agency
Landsat-8
U.S. Geological Survey
Landsat-7
U.S. Geological Survey
Landsat-7
U.S. Geological Survey
Japan Aerospace Exploration Agency via CEOS
USGS via CEOS
USGS via CEOS
USGS via CEOS
COMPOSITE
SPOTLIGHT
Spotlight imaging mode shows extremely detailed portions of relatively small sections at a time. A two-satellite team captured this high-resolution image of Hamilton Island over the Great Barrier Reef. These satellites cross the equator at the same local time each day, making the angle of sunlight consistent for comparisons over time.
Data from images taken over the same location over a long period can be combined to show cyclical patterns or to detect changes over time. The small images below are among hundreds of images used to create the composite at bottom, which showed the dropping water supply in rural Menindee Lakes, Australia, between 2000 and 2007.
Pléiades HR1 A and B
Centre National d’Études Spatiales (CNES) — France
Landsat-7
U.S. Geological Survey
Images by USGS; composite image by Geoscience Australia via CEOS
Copyright 2015 CNES/Distribution AIRBUS DS Via CEOS
SOURCE: Union of Concerned Scientists, NASA, National Oceanic and Atmospheric Administration, European Space Agency, Radio Amateur Satellite Corporation, Committee on Earth Observation Satellites.