14. June 2022
Radar data for remote sensing

Ger­man radar satel­lite Ter­raSAR-X – 15 years in space and still in per­fect shape

The TerraSAR-X and TanDEM-X satellites in formation flight
The Ter­raSAR-X and Tan­DEM-X satel­lites in for­ma­tion flight
Image 1/6, Credit: DLR (CC BY-NC-ND 3.0)

The TerraSAR-X and TanDEM-X satellites in formation flight

The twin satel­lites in for­ma­tion flight in their po­lar or­bits around the Earth. Ter­raSAR-X was launched on 15 June 2007; Tan­DEM-X has been fol­low­ing it since 21 June 2010. Both radar satel­lites pro­vide im­ages us­ing the Syn­thet­ic Aper­ture Radar tech­nique, as well as in­ter­fer­o­met­ric radar im­ages for three-di­men­sion­al map­ping of Earth's sur­face.
Munich city centre
Mu­nich city cen­tre
Image 2/6, Credit: DLR (CC BY-NC-ND 3.0)

Munich city centre

The im­age shown here was cre­at­ed us­ing a time se­ries of 60 Ter­raSAR-X im­ages ac­quired over a pe­ri­od of three years. The mul­ti­ple im­ages were pro­cessed in­to a false-colour im­age us­ing DLR’s RA­DI­AN soft­ware. Struc­tures that have changed dur­ing this pe­ri­od are shown in red. Veg­e­ta­tion is coloured green and un­changed struc­tures are shown in blue.The in­ner city of Mu­nich can be seen with the Marien­platz in the cen­tre, sur­round­ed by the Alt­stadtring, which fol­lows the for­mer sec­ond city wall. To the left is the Hof­garten and the En­glish Gar­den, be­low is the Is­ar with the Deutsches Mu­se­um on Mu­se­um Is­land and the Eu­ro­pean Patent Of­fice op­po­site, vis­i­ble as a bright cross-shaped struc­ture. At the top of the im­age is the There­sien­wiese, where the Spring Fes­ti­val and the Ok­to­ber­fest take place, and to the right is the main rail­way sta­tion with the rail­way tracks.
Karmostaj, Iran – a 'glacier' made of salt
Kar­mostaj, Iran – a 'glacier' made of salt
Image 3/6, Credit: DLR (CC BY-NC-ND 3.0)

Karmostaj, Iran – a 'glacier' made of salt

The Za­gros Moun­tains are lo­cat­ed in the south-east of Iran. This is one of the few places on Earth where rock salt oc­curs on the plan­et's sur­face. Due to tec­ton­ic stress­es be­tween the Eurasian and Ara­bi­an plates, salt domes are re­ac­ti­vat­ed, the plas­ti­cal­ly de­formable salt reach­es the sur­face and flows down the slopes like glaciers. The tec­ton­ic move­ments and changes in the salt glaciers are mea­sured and eval­u­at­ed us­ing da­ta from the Ter­raSAR-X mis­sion, joint­ly con­duct­ed by the DLR Re­mote Sens­ing Tech­nol­o­gy In­sti­tute and the Chair of Ge­ol­o­gy at LMU Mu­nich. This im­age shows the struc­tures of the salt rock that has reached the sur­face.
Congestion at the Panama Canal
Con­ges­tion at the Pana­ma Canal
Image 4/6, Credit: DLR (CC BY-NC-ND 3.0)

Congestion at the Panama Canal

This im­age shows the en­trance to the Pana­ma Canal near Pana­ma City, seen from the South Pa­cif­ic side. Nu­mer­ous ships can be seen wait­ing to pass through. En­larged de­tail 1 shows a ship pass­ing through the canal. De­tail 2 zooms in on the Co­colí Locks, with their three lock cham­bers in a row just north of the Port of Bal­boa docks. De­tail 3 shows the Is­la de Tabo­ga (left), Is­la Urabá (bot­tom cen­tre and Is­la Tabogu­il­la (right), and some ships ly­ing at an­chor. The many ships, con­tain­ers and cranes in the port re­flect the radar sig­nal par­tic­u­lar­ly well and ap­pear as bright struc­tures in the im­age.The im­age was ac­quired us­ing 'Wide Stripmap Mode', which is still the sub­ject of ex­per­i­men­ta­tion. This mode al­lows for a good com­pro­mise be­tween a large swathe width and high res­o­lu­tion. The scene shows an area 100 kilo­me­tres long and 43 kilo­me­tres wide, with a res­o­lu­tion of six me­tres.
Deforestation in the Amazon
De­for­esta­tion in the Ama­zon
Image 5/6, Credit: DLR (CC BY-NC-ND 3.0)

Deforestation in the Amazon

The as­sess­ment and mon­i­tor­ing of for­est re­sources is a key task for cur­rent and up­com­ing radar satel­lite mis­sions. The im­ages show an area in the Brazil­ian state of Rondô­nia, tak­en from DLR's glob­al Tan­DEM-X for­est map. On the left is the ‘con­ven­tion­al’ am­pli­tude im­age as gen­er­at­ed by Ter­raSAR-X alone. The low con­trast dif­fer­ences make it dif­fi­cult to recog­nise forest­ed ar­eas when on­ly a grey-scale im­age is avail­able.This changes when ad­di­tion­al in­for­ma­tion is avail­able, pro­vid­ed by the twin satel­lite Tan­DEM-X and in­clud­ed in a for­est map. The re­sult can be seen in the im­age on the right. The forest­ed ar­eas in green and cleared ar­eas in white can be clear­ly dis­tin­guished from one an­oth­er. With two radar 'eyes', more can be seen than with just one.In this case, in­ter­fer­o­met­ric da­ta ac­quired for the glob­al el­e­va­tion mod­el cre­at­ed us­ing the Ger­man radar satel­lite mis­sion Tan­DEM-X was used and al­go­rithms from the field of ar­ti­fi­cial in­tel­li­gence were ap­plied for glob­al da­ta pro­cess­ing.
Antarctica – ice dynamics and mass loss on the Ekblad Glacier
Antarc­ti­ca – ice dy­nam­ics and mass loss on the Ek­blad Glacier
Image 6/6, Credit: DLR (CC BY-NC-ND 3.0)

Antarctica – ice dynamics and mass loss on the Ekblad Glacier

This im­age shows part of the Queen Eliz­a­beth Range in the Transantarc­tic Moun­tains in Oc­to­ber 2021. In the cen­tre of the im­age is the Ek­blad Glacier, which flows in­to the Ross Ice Shelf. The gold­en arch on the right shows crevass­es around Cape Maude.Ter­raSAR-X pro­vides in­for­ma­tion about the sur­face struc­ture of the glaciers, the dy­nam­ics of the ice and, by al­low­ing com­par­isons be­tween re­peat­ed im­ages, the way these are chang­ing. This al­lows con­clu­sions to be drawn about flow ve­loc­i­ty and mass trans­port, which gives rise to find­ings about the melt­ing of glaciers and the as­so­ci­at­ed mass loss.
  • The German radar satellite TerraSAR-X celebrates its 15th anniversary in space on 15 June 2022.
  • TerraSAR-X allows researchers worldwide to document and better understand the changes on our planet.
  • TerraSAR-X serves two missions – the TerraSAR-X mission and the TanDEM-X mission for three-dimensional mapping of Earth's surface.
  • Experts are already working on the next generation of radar satellites for climate research and environmental observation – Tandem-L.
  • Focus: Space, Earth observation, radar technology

Fifteen years – who would have thought it? The German radar satellite TerraSAR-X, which was launched from the Baikonur Cosmodrome in Kazakhstan at 08:14 local time on 15 June 2007, was originally designed to last five and a half years – until the end of 2012. It has been delivering data of outstanding quality ever since, regardless of weather conditions, cloud cover and daylight levels. The scientific mission for TerraSAR-X and the satellite itself are operated by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR).

As it turns 15, TerraSAR-X can look back on 83,050 orbits of Earth, having travelled approximately 3.59 billion kilometres – a vast distance. If the satellite were travelling away from Earth in a straight line, it would have crossed the orbit of Uranus by late 2018 and would now be roughly midway between the orbits of Uranus and Neptune. At the grand old age of 15, TerraSAR-X is still in perfect shape.

Thanks to its robust design, combined with the highest measurement accuracy and stability, the satellite is still providing radar images that far surpass the original requirements for the mission. The high-resolution data and continuous view provided by TerraSAR-X enables researchers from all over the world to document and better understand the changes taking place on Earth, while facilitating the early detection of irreversible damage and pinpointing where intervention is needed. Such data provides an essential foundation for developing measures at a political and social level.

A data repository and research subject

Over its lifetime, TerraSAR-X has acquired more than 400,000 radar images, collecting 1.34 petabytes of data in the process. This is equivalent to 1,340,000 gigabytes or the streaming of around 270,000 high-definition feature films, which would take around 60 years to run through. The satellite’s legacy is becoming more comprehensive, more valuable and more widely used every day. More than 1100 leading researchers from 64 countries are now drawing upon and processing its data as part of 1875 ongoing research projects. Not only does the range of applications encompass the full spectrum of geosciences, including geology, glaciology, oceanography, meteorology and hydrology, but the radar data are also essential for environmental research, land use mapping, vegetation monitoring, and urban and infrastructure planning. Cartography, navigation, logistics, crisis management and defence and security also rely on TerraSAR-X data.

The satellite itself is the subject of research and development as well, particularly in the field of radar technology. With its flexible design, the radar system enables experiments to be conducted using new imaging modes such as a 'super wide angle' and 'super zoom', similar to a camera being fitted with different lenses. Officially referred to as 'WideScanSAR' and 'Staring Spotlight Mode', these were introduced during the course of the mission and then made available to users. The satellite continues to conduct radar experiments to test new techniques that might be used on future radar missions.

A third dimension with TanDEM-X

Since 21 June 2010, TerraSAR-X has been accompanied by the TanDEM-X satellite, which is almost identical in design. TanDEM-X and TerraSAR-X form the first reconfigurable Synthetic Aperture Radar (SAR) interferometer in space, recording precise height information for creating digital elevation models. This means that TerraSAR-X is now being used for two missions – the original TerraSAR-X mission and the TanDEM-X mission for three-dimensional mapping of Earth’s surface.

Despite its unprecedented longevity, the day will eventually come when TerraSAR-X is no longer able to fulfil its tasks. Resources such as propellant and battery capacity are steadily being depleted. However, if there are no major incidents, TerraSAR-X could remain in operation until the end of the 2020s.

Environmental observation in future – Tandem-L

With the TerraSAR-X and TanDEM-X satellite missions, DLR has set new standards in radar remote sensing. Its experts are already working on the next generation of radar satellites for climate research and environmental monitoring, in the form of Tandem-L, a highly innovative radar satellite mission. This could see Germany provide a system for the objective recording of the environment and the observation of environmental changes all over the world. The goal is to provide critical information to tackle highly relevant issues. For example, the latest report by the Intergovernmental Panel on Climate Change (IPCC) calls for the development of climate protection measures and the review of measures taken on a global scale, as a matter of urgency.

With Tandem-L, it would be possible to record a large number of dynamic processes in the biosphere, geosphere, cryosphere and hydrosphere with unprecedented quality and resolution. The new satellite constellation could provide up-to-date 3D imaging of Earth's entire landmass on a weekly basis and measure seven essential climate variables simultaneously. In doing so, Tandem-L would make a significant contribution towards a better understanding of processes that are now seen as drivers of local and global climate change.

About the mission

The DLR Microwaves and Radar Institute and Remote Sensing Technology Institute, together with the German Remote Sensing Data Center and the German Space Operations Center, form the SAR Center of Excellence. The institutes and facilities involved cover all areas of the TerraSAR-X mission, from sensor technologies and mission design to high-precision operational processing, all the way through to delivering refined end-user products. Together, these institutes and facilities are responsible for the construction and operation of the mission's ground segment and the coordination of its scientific utilisation.

The TerraSAR-X mission is being implemented on behalf of the German Aerospace Center (DLR), with funding from the Federal Ministry of Economic Affairs and Climate Action. It is the first German satellite to have been created as part of a Public–Private Partnership (PPP) between DLR and Airbus Defence and Space GmbH (formerly Astrium). Airbus Defence and Space shared the costs of the development, construction and deployment of the satellite. The Geo-Intelligence Programme Line at Airbus D&S (formerly Infoterra GmbH) is responsible for the commercial marketing of the data. Since 2016, the project has been operated under a continuation agreement with Airbus.

Contact
  • Bernadette Jung
    Ed­i­tor
    Ger­man Aerospace Cen­ter (DLR)

    Cor­po­rate Com­mu­ni­ca­tions
    Telephone: +49 8153 28-2251
    Fax: +49 8153 28-1243
    Münchener Straße 20
    82234 Weßling
    Contact
  • Dr.-Ing. Stefan Buckreuß
    Ger­man Aerospace Cen­ter (DLR)
    Mi­crowaves and Radar In­sti­tute
    Münchener Straße 20
    82234 Oberpfaffenhofen-Weßling
    Contact

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