TerraSAR-X

Last updated

TerraSAR-X
TerraSAR-X and TanDEM-X satellites in formation flight over Europa.jpg
An rendering of the satellites TerraSar-X and TanDEM-X flying over Europe.
Mission type Radar imaging
Operator DLR
COSPAR ID 2007-026A OOjs UI icon edit-ltr-progressive.svg
SATCAT no. 31698
Mission durationElapsed: 16 years, 11 months, 24 days
Spacecraft properties
Manufacturer EADS Astrium
Launch mass1,230 kg (2,710 lb)
Start of mission
Launch date15 June 2007, 02:14 (2007-06-15UTC02:14Z) UTC
Rocket Dnepr
Launch site Baikonur 109/95
Contractor ISC Kosmotras
Orbital parameters
Reference system Geocentric
Regime Low Earth
Semi-major axis 6,886.39 kilometres (4,279.00 mi) [1]
Eccentricity 0.0001445 [1]
Perigee altitude 514 kilometres (319 mi) [1]
Apogee altitude 516 kilometres (321 mi) [1]
Inclination 97.44 degrees [1]
Period 94.79 minutes [1]
Epoch 25 January 2015, 02:35:23 UTC [1]
TerraSARX Logo.png  

TerraSAR-X, is an imaging radar Earth observation satellite, a joint venture being carried out under a public-private-partnership between the German Aerospace Center (DLR) and EADS Astrium. The exclusive commercial exploitation rights are held by the geo-information service provider Astrium. TerraSAR-X was launched on 15 June 2007 and has been in operational service since January 2008. With its twin satellite TanDEM-X, launched 21 June 2010, TerraSAR-X acquires the data basis for the WorldDEM, the worldwide and homogeneous DEM available from 2014.

Contents

Satellite and mission

Radar image First bistatic radar image acquired by the twin satellites TanDEM-X and TerraSAR-X in tandem flight.jpg
Radar image

Using a phased array synthetic aperture radar (SAR) antenna (X-band wavelength 31mm, frequency 9.65 GHz [2] ), TerraSAR-X provides radar images of the entire planet from an Earth polar orbit of 514km altitude. This is selected so that the satellite follows a Sun-synchronous orbit. This specific orbit means that the satellite moves along the Day-Night boundary of the Earth and allows it to present the same face to the Sun: thus, providing the best solar incidence angles to its solar cells for power. TerraSAR-X is designed to carry out its task for five years, independent of weather conditions and illumination, and provides radar images with a resolution of up to 1m.

TerraSAR-X imaging modes

TerraSAR-X acquires radar data in the following three main imaging modes:

In addition, the design of TerraSAR-X's SAR antenna allows a variety of polarimetric combinations: single or dual polarization, or full polarimetric data takes.

Depending on the desired application, one of four different processing levels is selected:

TanDEM-X and WorldDEM Akida

TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) is a second, similar spacecraft launched on 21 June 2010 from Baikonur Cosmodrome in Kazakhstan. Since October 2010, TerraSAR-X and TanDEM-X have orbited in close formation at distances of a few hundred metres and record data synchronously. [4] This twin satellite constellation will allow the generation of WorldDEM, the global digital elevation models (DEMs). With higher accuracy, coverage and quality – WorldDEM is a consistent DEM of the Earth's land surface is envisaged to be acquired and generated within three years after launch. Available from 2014, WorldDEM is to feature a vertical accuracy of 2m (relative) and 10m (absolute), within a horizontal raster of approximately 12x12 square meters, slightly varying depending on the geographic latitude. [5]

Satellite radar

Radar stands for Radio Detection and Ranging and contains traditionally:

Satellite radar systems came into operation over fifteen years after the adoption of optical camera systems. The resolution is lower than optical imaging, but radar can gather information at any time of the day or night and independent of cloud cover.

Early radar satellite techniques were e.g. the Altimetrie (leveling over the sea), NASA's SEASAT (launched in 1978), regulation of waves/wind or soil data. The military has used radar since the late 1930s and radar satellites at least since 1978. [6]

Novel design features of TerraSAR X

TerraSAR X introduced some technical-industrial novelties. One of these innovations is a kind of zoom shot, with the resolution and scanning field vice versa changeable in a 1:10 relationship, either a larger area to grasp or a small area with the highest possible resolution.

Furthermore, the antenna can be aligned by electronics within an angle range so that the point of view is adjustable. Earlier radar satellites could radiate the antenna only in one direction.

Scanning and trajectory

With the adjustable angle radar sensor – along with other course refinements (precession by the earth flattening) – any place on earth can be observed preferentially within 1 to 3 days.

For a specific point on the Earth's equator, TerraSAR X has a revisit cycle of 11 days. The revisit time decreases towards the poles, e.g. Northern Europe has a revisit time of typically 3–4 days.

Ground segment

The ground operating mechanism and controls for the TerraSAR X is developed by the DLR in Oberpfaffenhofen. It consists of Mission Operating Equipment, the Payload ground segment and the Instrument Operation and Calibration Segment. At the base of the ground segment lies the German Space Operation Center (GSOC), the German Remote Sensing Datum Center (DFD) as well as Institutes for Methodology of Remote Sensing (MF) and the Institute for High-Frequency Engineering and Radar Systems (HR) which are all part of the DLR.

Applications

Applications of the high-resolution TerraSAR-X radar imagery include:

Scientific use of TerraSAR-X data

The scientific use of the TerraSAR-X data will be coordinated through the TerraSAR-X Science Service System by the DLR. [11] The new-quality data records, as provided by TerraSAR-X, will offer a vast amount of new research incentives, for instance in ecology, geology, hydrology and oceanography. The smallest movements of the Earth's surface (plate tectonics, volcanism, earthquake) are further scientific fields of application.

Commercial use of TerraSAR-X data

To ensure the commercial success of the mission, EADS Astrium founded its 100% subsidiary Infoterra in 2001; the company being responsible for establishing a commercial market for TerraSAR-X data as well as TerraSAR-X-based geo-information products and services.

See also

The radar remote sensing satellites TanDEM X and Terra SAR X photographed while flying in close formation (photo by Marco Langbroek, Leiden, the Netherlands). Movement is from lower right to upper left in this 10-second exposure. TandemX TerraSarXduo satellites.jpg
The radar remote sensing satellites TanDEM X and Terra SAR X photographed while flying in close formation (photo by Marco Langbroek, Leiden, the Netherlands). Movement is from lower right to upper left in this 10-second exposure.

Radars on the Space Shuttle:

(the TerraSAR-X authors were involved in SRL and SRTM missions)

Related Research Articles

<span class="mw-page-title-main">Digital elevation model</span> 3D computer-generated imagery and measurements of terrain

A digital elevation model (DEM) or digital surface model (DSM) is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet, moon, or asteroid. A "global DEM" refers to a discrete global grid. DEMs are used often in geographic information systems (GIS), and are the most common basis for digitally produced relief maps. A digital terrain model (DTM) represents specifically the ground surface while DEM and DSM may represent tree top canopy or building roofs.

<span class="mw-page-title-main">German Aerospace Center</span> German research center for aerospace and power engineering

The German Aerospace Center is the national center for aerospace, energy and transportation research of Germany, founded in 1969. It is headquartered in Cologne with 35 locations throughout Germany. The DLR is engaged in a wide range of research and development projects in national and international partnerships.

<span class="mw-page-title-main">Satellite imagery</span> Images taken from an artificial satellite

Satellite images are images of Earth collected by imaging satellites operated by governments and businesses around the world. Satellite imaging companies sell images by licensing them to governments and businesses such as Apple Maps and Google Maps.

<span class="mw-page-title-main">Satellite geodesy</span> Measurement of the Earth using satellites

Satellite geodesy is geodesy by means of artificial satellites—the measurement of the form and dimensions of Earth, the location of objects on its surface and the figure of the Earth's gravity field by means of artificial satellite techniques. It belongs to the broader field of space geodesy. Traditional astronomical geodesy is not commonly considered a part of satellite geodesy, although there is considerable overlap between the techniques.

<span class="mw-page-title-main">Space-based radar</span> Use of radar systems mounted on satellites

Space-based radar or spaceborne radar is a radar operating in outer space; orbiting radar is a radar in orbit and Earth orbiting radar is a radar in geocentric orbit. A number of Earth-observing satellites, such as RADARSAT, have employed synthetic aperture radar (SAR) to obtain terrain and land-cover information about the Earth.

<span class="mw-page-title-main">Seasat</span> American ocean observation satellite

Seasat was the first Earth-orbiting satellite designed for remote sensing of the Earth's oceans and had on board one of the first spaceborne synthetic-aperture radar (SAR). The mission was designed to demonstrate the feasibility of global satellite monitoring of oceanographic phenomena and to help determine the requirements for an operational ocean remote sensing satellite system. Specific objectives were to collect data on sea-surface winds, sea-surface temperatures, wave heights, internal waves, atmospheric water, sea ice features and ocean topography. Seasat was managed by NASA's Jet Propulsion Laboratory and was launched on 27 June 1978 into a nearly circular 800 km (500 mi) orbit with an inclination of 108°. Seasat operated until 10 October 1978 (UTC), when a massive short circuit in the Agena-D bus electrical system ended the mission.

<span class="mw-page-title-main">Shuttle Radar Topography Mission</span> Project to create a digital topographic database of Earth

The Shuttle Radar Topography Mission (SRTM) is an international research effort that obtained digital elevation models on a near-global scale from 56°S to 60°N, to generate the most complete high-resolution digital topographic database of Earth prior to the release of the ASTER GDEM in 2009. SRTM consisted of a specially modified radar system that flew on board the Space Shuttle Endeavour during the 11-day STS-99 mission in February 2000. The radar system was based on the older Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR), previously used on the Shuttle in 1994. To acquire topographic data, the SRTM payload was outfitted with two radar antennas. One antenna was located in the Shuttle's payload bay, the other – a critical change from the SIR-C/X-SAR, allowing single-pass interferometry – on the end of a 60-meter (200-foot) mast that extended from the payload bay once the Shuttle was in space. The technique employed is known as interferometric synthetic aperture radar. Intermap Technologies was the prime contractor for processing the interferometric synthetic aperture radar data.

<span class="mw-page-title-main">SAR-Lupe</span> German military reconnaissance satellite system

SAR-Lupe is Germany's first reconnaissance satellite system and is used for military purposes. SAR is an abbreviation for synthetic-aperture radar, and "Lupe" is German for magnifying glass. The SAR-Lupe program consists of five identical (770 kg) satellites, developed by the German aeronautics company OHB-System, which are controlled by a ground station responsible for controlling the system and analysing the retrieved data. A large data archive of images will be kept in a former Cold War bunker belonging to the Kommando Strategische Aufklärung of the Bundeswehr. The total price of the satellites was over 250 million Euro.

<span class="mw-page-title-main">STS-68</span> 1994 American crewed spaceflight

STS-68 was a human spaceflight mission using Space ShuttleEndeavour that launched from Kennedy Space Center, Florida on September 30, 1994.

<span class="mw-page-title-main">Interferometric synthetic-aperture radar</span> Geodesy and remote sensing technique

Interferometric synthetic aperture radar, abbreviated InSAR, is a radar technique used in geodesy and remote sensing. This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite or aircraft. The technique can potentially measure millimetre-scale changes in deformation over spans of days to years. It has applications for geophysical monitoring of natural hazards, for example earthquakes, volcanoes and landslides, and in structural engineering, in particular monitoring of subsidence and structural stability.

<span class="mw-page-title-main">COSMO-SkyMed</span> Italian radar observation satellite system

COSMO-SkyMed is an Earth-observation satellite space-based radar system funded by the Italian Ministry of Research and Ministry of Defence and conducted by the Italian Space Agency (ASI), intended for both military and civilian use. The prime contractor for the spacecraft was Thales Alenia Space. COSMO SkyMed is a constellation of four dual use Intelligence, surveillance, target acquisition, and reconnaissance (ISR) Earth observation satellites with a synthetic-aperture radar (SAR) as main payload, the result of the intuition of Giorgio Perrotta in the early nineties. The synthetic-aperture radar was developed starting in the late nineties with the SAR 2000 program funded by ASI.

<span class="mw-page-title-main">Sentinel-1</span> Earth observation satellite

Sentinel-1 is the first of the Copernicus Programme satellite constellations conducted by the European Space Agency. The mission was originally composed of a constellation of two satellites, Sentinel-1A and Sentinel-1B, which shared the same orbital plane. Two more satellites, Sentinel-1C and Sentinel-1D are in development. Sentinel-1B was retired following a power supply issue on December 23, 2021, leaving Sentinel-1A the only satellite of the constellation currently operating. Sentinel-1C is currently planned to launch in the final quarter of 2024.

<span class="mw-page-title-main">Spaceborne Imaging Radar</span> NASA radar

The Spaceborne Imaging Radar (SIR) – full name 'Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR)', is a synthetic aperture radar which flew on two separate shuttle missions. Once from the Space Shuttle Endeavour in April 1994 on (STS-59) and again in October 1994 on (STS-68). The radar was run by NASA's Space Radar Laboratory. SIR utilizes 3 radar frequencies: L band, C band (6 cm) and X band (3 cm), allowing for study of geology, hydrology, ecology and oceanography. Comparing radar images to data collected by teams of people on the ground as well as aircraft and ships using simultaneous measurements of vegetation, soil moisture, sea state, snow and weather conditions during each flight. The imaging radar was able to take images anytime regardless of clouds cover. The Radar-C system was built and operated by NASA's Jet Propulsion Laboratory (JPL). The mission was a joint work of NASA with the German and Italian space agencies. Each of the week long mission scanned about 50 million square kilometers of the Earth's surface,.

<span class="mw-page-title-main">TanDEM-X</span> German Earth observation satellite

TanDEM-X is the name of TerraSAR-X's twin satellite, a German Earth observation satellite using SAR - a modern radar imaging technology. Implemented in a Public-Private-Partnership between the German Aerospace centre (DLR) and EADS Astrium, it is a second, almost identical spacecraft to TerraSAR-X (TSX). TanDEM-X (TDX) is also the name of the satellite mission flying the two satellites in a closely controlled formation with typical distances between 250 and 500 m. The twin satellite constellation allowed the generation of WorldDEM global digital elevation models starting in 2014.

The modular optoelectronic multispectral scanner (MOMS) is a scanning system for spaceborne, geoscientific remote sensing applications used in satellite navigation systems for sensing atmospheric and oceanic systems. The scanner is combination of separate spectrometer blocks.

<span class="mw-page-title-main">NISAR (satellite)</span> Joint NASA-ISRO synthetic radar aperture spacecraft

The NASA-ISRO Synthetic Aperture Radar (NISAR) mission is a joint project between NASA and ISRO to co-develop and launch a dual-frequency synthetic aperture radar on an Earth observation satellite. The satellite will be the first radar imaging satellite to use dual frequencies. It will be used for remote sensing, to observe and understand natural processes on Earth. For example, its left-facing instruments will study the Antarctic cryosphere. With a total cost estimated at US$1.5 billion, NISAR is likely to be the world's most expensive Earth-imaging satellite.

<span class="mw-page-title-main">High Resolution Wide Swath SAR imaging</span>

High Resolution Wide Swath (HRWS) imaging is an important branch in synthetic aperture radar (SAR) imaging, a remote sensing technique capable of providing high resolution images independent of weather conditions and sunlight illumination. This makes SAR very attractive for the systematic observation of dynamic processes on the Earth's surface, which is useful for environmental monitoring, earth resource mapping and military systems.

<span class="mw-page-title-main">Paz (satellite)</span> Spanish military Earth observation satellite

Paz is a Spanish Earth observation and reconnaissance satellite launched on 22 February 2018. It is Spain's first spy satellite. The satellite is operated by Hisdesat. Paz was previously referred to as SEOSAR.

RISAT-2B, or Radar Imaging Satellite-2B is an Indian radar reconnaissance satellite that is part of India's RISAT programme and the third satellite in the series. It is built by Indian Space Research Organisation (ISRO) to replace RISAT-2.

<span class="mw-page-title-main">German Antarctic Receiving Station</span> German receiving station in Antarctica

German Antarctic Receiving Station or GARS O'Higgins is a German polar research station in Antarctica.

References

  1. 1 2 3 4 5 6 7 "TERRA SAR X Satellite details 2007-026A NORAD 31698". N2YO. 25 January 2015. Retrieved 25 January 2015.
  2. "Observing Systems Capability Analysis and Review Tool: SAR-X Instrument details". World Meteorological Organization. 15 June 2021. Retrieved 7 June 2023.
  3. StripMap & ScanSAR: acquisition length extendable to up to 1,650 km.
  4. DLR – Blogs – The satellites have 'eye contact'
  5. GIM International: Weber, Marco; Koudogbo, Fifamè, January 2009, TerraSAR-X 1m Spaceborne Radar – Use, Features, Products and TanDEM-X.
  6. (Jensen, J. R. 2007. Remote Sensing of the Environment: An Earth Resource Perspective)
  7. GeoBerichte 14, Landesamt für Bergbau, Energie und Geologie in Niedersachsen:Schrage, Thomas;Jacob, Philipp, June 2009, Flächenverbrauch und Bodenversigelung in Niedersachsen.
  8. GIM International: Balz, Timo; Scheuchl, Bernd;Li, Deren, October 2008, The Sichuan Earthquake(1)-Satellite Imagery for Rapid Response.
  9. GIM International: Shao, Yun; Scheuchl, Bernd, November 2008, The Sichuan Earthquake (2)- Spaceborne SAR in Earthquake Response.
  10. GIM International: Koudogbo, Fifamè; Müller, Marc; Scheuchl, Bernd, December 2008, The Sichuan Earthquake (3)- Satellite-based Global Flood Response.
  11. TerraSAR-X Science Service System