Another Eye in the Sky

Five years ago today — September 18, 2007 — DigitalGlobe launched WorldView 1, a commercial remote sensing satellite, from Vandenberg AFB on a Delta II rocket.

(WorldView 1 image of President Obama’s inauguration. Image from DigitalGlobe site, for editorial use; available for purchase in their online store.)

WorldView 1 was built by Ball Aerospace for DigitalGlobe, and featured a “panchromatic” camera — sensitive to all colors in the visible spectrum — with half-meter resolution. Even though it’s a commercial imager, the National Imagery and Mapping Agency was among its primary customers.

Here’s a complete data sheet about the satellite.

DigitalGlobe launched the WorldView 2 companion spacecraft in December 2009.


Note: I tried to find DigitalGlobe’s “Images for the Media” page (, to pull an image they had already tagged for editorial use, but that section of their web site appeared no longer to exist.

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Surveying the Ocean's Topography, from Space

Twenty years ago today — August 10, 1992 — an Ariane 42P launch vehicle launched from Kourou, French Guiana, carrying the TOPEX/Poseidon satellite.

(TOPEX/Poseidon. NASA image.)

Officially the Ocean Topography Experiment, TOPEX/Poseidon was a joint mission between NASA and France’s Centre National d’Etudes Spatiales to measure sea-surface heights from a space-based radar platform. It was also the second spacecraft in the “Mission to Planet Earth” program.

The TOPEX/Poseidon spacecraft was decommissioned in January 2006, but the Jason-1 and Jason-2 follow-on spacecraft are continuing the mission. The Ocean Surface Topography page presents details on all of the missions associated with the space-based study of our world’s oceans.

So, next time you’re at the beach and thinking about how high the waves are, remember that satellites hundreds of miles above you are looking down, thinking about the same thing.

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Revolutionizing Civilian Remote Sensing: The Launch of Landsat 1

Forty years ago today — July 23, 1972 — the Earth Resources Technology Satellite (ERTS) 1 launched from Vandenberg AFB atop a Delta rocket.

Renamed Landsat 1, the satellite was the first to demonstrate global remote sensing for “agricultural and forestry resources, geology and mineral resources, hydrology and water resources, geography, cartography, environmental pollution, oceanography and marine resources, and meteorological phenomena.”

(Landsat images of Mount St Helens. NASA image.)

According to this Landsat page, the choice of wavelengths for Landsat’s multispectral scanner (MSS) “was primarily based on forestry and geologic applications that had traditionally used Color IR photography.” At the time, multispectral imaging was “secondary and highly experimental,” according to this page, but scientists soon recognized the utility of the multispectral data.

The spacecraft operated until January 1978, five years longer than expected.

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A New Generation of Environmental Monitoring Capabilities

Thirty years ago today — July 16, 1982 — Landsat 4 launched atop a Delta rocket out of Vandenberg AFB.

(Landsat 4. NASA image.)

Though it was the fourth in the Landsat series of spacecraft, Landsat 4 “was a major step forward in global remote-sensing applications.” According to this NASA page,

In addition to the Multispectral Scanner System (MSS) instrument, Landsat 4 (and Landsat 5) carried a sensor with improved spectral and spatial resolution, i.e., the new satellites could see a wider (and more scientifically-tailored) portion of the electromagnetic spectrum and could see the ground in greater detail. This new instrument was known as the Thematic Mapper (TM).

The Landsat 4 TM instrument had seven spectral bands. Data was collected from the blue, green, red, near-infrared, mid-infrared (2 bands) and thermal infrared portions of the electromagnetic spectrum.

The Thematic Mapper was an important addition to the environmental monitoring instrumentation, and later Landsat spacecraft carried improved versions of it.

Landsat 4 was designed to operate for 3 years. Although some of its components failed, it continued to operate in a limited capacity until 1993. Thereafter, the spacecraft sent telemetry data until 2001, when it was decommissioned.

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Star Wars Day Space History …

… from our little part of this galaxy, not that long ago.

Forty-five years ago today — May 4, 1967 — an Atlas Agena rocket launched from Cape Canaveral carrying the Lunar Orbiter 4 on its mission to the Moon.

Because the previous three Lunar Orbiters had “completed the required needs for Apollo mapping and site selection,” NASA tasked this fourth orbiter to “perform a broad systematic photographic survey of lunar surface features in order to increase the scientific knowledge of their nature, origin, and processes, and to serve as a basis for selecting sites for more detailed scientific study by subsequent orbital and landing missions.”

Lunar Orbiter 4 developed problems with the camera door, however: it did not open and close correctly when commanded, and mission controllers feared that it might stick closed so they commanded it to remain open.

This required extra attitude control manuevers on each orbit to prevent light leakage into the camera which would ruin the film. On 13 May it was discovered that light leakage was damaging some of the film, and the door was tested and partially closed. Some fogging of the lens was then suspected due to condensation resulting from the lower temperatures. Changes in the attitude raised the temperature of the camera and generally eliminated the fogging. Continuing problems with the readout drive mechanism starting and stopping beginning on 20 May resulted in a decision to terminate the photographic portion of the mission on 26 May.

Even with those problems, the spacecraft was able to read and transmit “419 high resolution and 127 medium resolution frames were acquired covering 99% of the Moon’s near side at resolutions from 58 meters to 134 meters.”

And in more recent space history …

Just a decade ago, on this date in 2002, the remote sensing spacecraft Aqua was launched from Vandenberg AFB by a Delta-II rocket.

(A depiction of the “A-Train” formation of satellites in similar orbits. Aqua was the first vehicle in the A-Train. NASA image.)

Originally known as Earth Observation System Afternoon One (EOS-PM1) for the time of day it would cross the equator, the mission was renamed Aqua

for the large amount of information that the mission is collecting about the Earth’s water cycle, including evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover on the land and ice. Additional variables also being measured by Aqua include radiative energy fluxes, aerosols, vegetation cover on the land, phytoplankton and dissolved organic matter in the oceans, and air, land, and water temperatures.

If I recall, one of the folks I worked with at the Defense Technology Security Administration came to us from the Aqua program. Pretty cool.

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Space History Today: Fourth Hubble Servicing Mission

Ten years ago today — March 1, 2002 — the Space Shuttle Columbia launched from the Kennedy Space Center on the fourth servicing mission to the Hubble Space Telescope.

(The Hubble Space Telescope in the shuttle cargo bay for repairs and upgrades, with a background of sunrise “airglow” on Earth’s horizon. NASA image.)

Astronauts Scott D. Altman, Duane G. Carey, John M. Grunsfeld, Nancy J. Currie, James H. Newman, Richard M. Linnehan, and Michael J. Massimino made up the crew of STS-109, and accomplished five spacewalks on this important mission.

The crew

  • removed and replaced the telescope’s two solar arrays with new, higher-efficiency arrays
  • installed a new Reaction Wheel Assembly
  • replaced the Power Control Unit
  • replaced Hubble’s Faint Object Camera with the Advanced Camera for Surveys
  • installed the Electronic Support Module and a cryocooler and Cooling System Radiator for an experimental cooling system for the Near-Infrared Camera and Multi-Object Spectrometer

All of us who have enjoyed Hubble’s images and discoveries through the years can appreciate the effort to maintain and improve it over its operational life. Well done!


For a little bonus space history, on the same day that Columbia launched, the European Space Agency launched ENVISAT-1 on an Ariane-5 rocket out of Kourou. At 8.1 tonnes (nearly 18,000 lb), ENVISAT-1 was “reported to be the most massive and expensive of the European satellites.” It carried ten instruments for remote sensing of terrestrial environmental conditions such as global warming and desertification.

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India's Space Program Matures

Five years ago today — January 10, 2007 — a PSLV-C7 rocket launched from Sriharikota, India, carrying four spacecraft including India’s first recoverable space capsule.

(CartoSat-2 remote sensing satellite. ISRO image.)

The largest of the four spacecraft was CartoSat-2, a three-axis-stabilized remote sensing platform with one-meter resolution. The SRE-1 technology demonstrator was the recoverable capsule, equipped with a heat shield for re-entry and a floatation system. SRE-1 “re-entered in the Bay of Bengal precisely as planned at 04:14 UT on 22 January at 150 km east of Sriharikota, and was hauled by a helicopter from a coast guard vessel.”

The other two spacecraft were LAPAN-Tubsat, a microsatellite built by Indonesia, and PehuenSat-1, a picosatellite from Argentina.

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Dual Launch on a Delta-II, and an Old Test Satellite

Ten years ago today — December 7, 2001 — a Delta-II launch vehicle carried two satellites into orbit from Vandenberg AFB.

(Artist’s conception of the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics [TIMED] satellite. NASA image.)

Jason-1 was a joint mission between the U.S. and France: an oceanographic satellite intended to monitor the level and wave heights of the ocean surface. The Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics, or TIMED, satellite was designed to study “the physical and chemical processes acting within and upon the coupled mesosphere,” i.e., that portion of the atmosphere between 60-180 km altitude. This region of the atmosphere “is difficult to study because it is too high for even the largest research balloons and still dense enough to quickly cause a satellite to decay from orbit.”

In earlier space history, on this date 45 years ago, Applications Technology Satellite 1 (ATS-1) launched from Cape Canaveral atop an Atlas Agena rocket. ATS-1 was a test platform for new spacecraft design concepts, particularly propulsion and attitude control, as well as a remote sensing satellite that collected meterological data and cloud cover images. ATS-1 also tested improved satellite communications.

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I haven’t had a lot of space history posts recently. I try to limit myself to anniversaries in multiples of 5 years, to keep from repeating things, and to keep the pace from getting overwhelming. I also try not to include “routine” events like the launch of the Nth in a series of satellites … not that anything about space operations has become truly routine, of course. But here’s one for the record:

Five years ago today — October 26, 2006 — a Delta 2 rocket out of Cape Canaveral placed two solar observatories in orbit.

(STEREO spacecraft. NASA image.)

The Solar Terrestrial Relations Observatory consisted of two identical spacecraft, STEREO-A and STEREO-B. Once in space, the two satellites were allowed to drift into different heliocentric orbits: STEREO-B ahead of the Earth (leading), and STEREO-A behind the Earth (lagging). From those vantage points, their observations could be combined to image the Sun “stereographically” and predict whether a coronal mass ejection was heading toward the Earth.

On February 6th of this year, STEREO A and B reached 180 degrees of separation, which “enabled, for the first time, the simultaneous observation of the entire Sun.”

In other news, I’m heading to the World Fantasy Convention today. Folks have been urging me to go to WFC for years; it’s a small convention, primarily of SF&F professionals. It seems a little odd to think of myself as an SF&F professional in my own right, but my 3rd and 4th professional sales are forthcoming: more on those later, when the contracts are signed (or when the editors give me the okay).

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ADEOS (Midori) and the First Frenchwoman in Space

Fifteen years ago today — August 17, 1996 — the Japanese launched the first of a series of environmental remote sensing satellites, and the Russians launched a mission to Mir that included the first female French astronaut.

(Artist’s conception of ADEOS spacecraft. JAXA image.)

ADEOS, which was later renamed “Midori,” was the ADvanced Earth Observation Satellite and was launched from Tanegashima Space Center on an H-2 rocket. The spacecraft operated until mid-1997, measuring winds, ocean surfaces temperature, atmospheric aerosols, ozone, and greenhouse gases. You can read more about the first ADEOS/Midori spacecraft on this JAXA page.

And Soyuz TM-24 launched from the Baikonur Cosmodrome atop a Soyuz-U launch vehicle, bound for the Mir space station. Russian cosmonauts Valery G. Korzun and Alexander Y. Kaleri flew on this mission with Claudie Andre-Deshays, the first French woman in space.

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