German military reconnaissance satellite system
A model of a SAR-Lupe satellite on top of a Russian
Kosmos-3M
rocket
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
[1]
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 Aufklarung
(Strategic Reconnaissance Command) of the
Bundeswehr
. The total price of the satellites was over 250 million
Euro
.
[2]
Specifications
[
edit
]
SAR-Lupe's "high-resolution" images can be acquired day or night through all weather conditions. The satellites are able to provide up-to-date imagery from almost all regions of the world.
[2]
The first satellite was launched from
Plesetsk
in
Russia
on 19 December 2006, about a year after the intended launch date; four more satellites were launched at roughly six-month intervals, and the entire system achieved full operational readiness on 22 July 2008.
[3]
The constellation is planned for 10 years of operational life.
[2]
The five satellites operate in three 500-kilometre orbits in planes roughly 60° apart. They use an
X-band
radar with a 3-metre dish, providing a resolution of about 50 centimetres over a frame size of 5.5 km on a side ("spotlight mode", in which the satellite rotates to keep the dish pointed at a single target) or about 1 metre over a frame size of 8 km × 60 km ("stripmap mode", in which the satellite maintains a fixed orientation over the Earth, and the radar image is formed simply by the satellite's motion along its orbit). Response time for imaging of a given area is 10 hours or less.
Thales Alenia Space
provided the core of the synthetic-aperture radar sensors.
[4]
History
[
edit
]
The SAR-Lupe satellites are the first German military satellites.
[2]
The testing of SAR-Lupe involved an inverse procedure, in which the satellite, mounted in a
radome
on Earth, was used to image the
International Space Station
, whose orbit is reasonably close to the one the satellite will eventually be in. One-metre resolution at the ISS was apparently achieved.
[
citation needed
]
On 30 July 2002 a cooperation treaty between
Germany
and
France
was signed, under which the SAR-Lupe satellites and the French
Helios
optical reconnaissance satellite will operate jointly. Other EU countries have been invited to join as well, and
Italy
has shown considerable interest.
Radar component
[
edit
]
XSAR of SAR-Lupe is observing in X-band (center frequency of 9.65 GHz corresponding to a wavelength of 3.1 cm).
- Global observation coverage capability.
- Use of a parabolic SAR reflector antenna of 3.3 m × 2.7 m size. The choice of using a single-beam
offset reflector antenna
instead of an active beam-steering antenna represented a major cost saving in the development of the instrument. SAR-Lupe uses a single-beam offset reflector antenna and a
travelling-wave tube
(TWT) transmitter, illuminated by a feed horn on a deployable boom. The highly efficient TWT and a low-loss high-gain antenna are providing good power potential for radar with efficient DC power utilization.
Prior to an image acquisition, the satellite rolls in an appropriate position and stabilizes its attitude. Then, the SAR image is acquired. After that, the satellite rolls back into its standby attitude and continues to charge its batteries, preparing itself for the next SAR image acquisition.
- Number of scenes of area of interest: ≥ 30/day.
- System response time: < 36 hours.
- System availability: 95%.
- Automated monitoring and control of the constellation via a ground control station.
- Automated data reception and image processing.
- LEOP (launch and early orbit phase) support is provided by DLR/GSOC.
- The mean response time of the system is in the range of 10 hours. System availability is provided by the distribution of the satellites in their orbital planes.
- The modular interface design of the ground segment permits also future integration into an international reconnaissance network (mutual utilization of the system, etc.).
- SAR imaging modes provided: stripmap and spotlight. Stripmap imaging involves antenna pointing into a fixed direction (normally in cross-track). Internally, these modes are referred to as “Strip-SAR” and “Slip-SAR”. Strip-SAR observations are conducted in the nadir direction. In Slip-SAR mode, the entire spacecraft is rotated into the direction of the target to increase the integration time and therefore the in-track resolution.
- Spatial resolution of SAR data: 0.5 m in spotlight mode for a scene of about 5.5 km × 5.5 km in size; a stripmap scene has a size of 60 km × 8 km. It can provide NESZ (noise equivalent sigma naught) range up to ?19.91 dB.
- Satellite operations permit “spotlight imaging” of a scene. This involves rotation of the entire spacecraft about a target area to increase the integration time of the scene (the SAR beacon is pointable). In SAR-Lupe terminology, spotlight imaging is referred to as “Slip-SAR”.
- An onboard image storage capability of 128 Gbit (EOL) is provided.
- The main image products are: 1) stripmap scenes of size 60 km × 8 km, and 2) square scenes of 5.5 km × 5.5 km in size.
- The following additional products can also be generated: a) elevation models from multipass interferometric products, b) multipass stereo products, c) change detection products, d) products with enhanced radiometric resolution.
Launches
[
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]
Satellite
|
COSPAR
|
Date
|
Carrier rocket
|
Launch site
|
Launch status
|
SAR-Lupe-1
|
2006-060A
|
19 December 2006
|
Cosmos-3M
[1]
|
Plesetsk
|
Success
|
SAR-Lupe-2
|
2007-030A
|
2 July 2007
|
Cosmos-3M
[2]
|
Plesetsk
|
Success
|
SAR-Lupe-3
|
2007-053A
|
1 November 2007
|
Cosmos-3M
[3]
|
Plesetsk
|
Success
|
SAR-Lupe-4
|
2008-014A
|
27 March 2008
|
Cosmos-3M
[4]
[5]
|
Plesetsk
|
Success
|
SAR-Lupe-5
|
2008-036A
|
22 July 2008
|
Cosmos-3M
[6]
|
Plesetsk
|
Success
|
SARah-1
|
2022-063A
|
18 June 2022
|
Falcon 9 Block 5
|
Vandenberg
SLC-4E
|
Success
|
SARah-2
|
2023-204_
|
24 December 2023
|
Falcon 9 Block 5
|
Vandenberg
SLC-4E
|
Success
|
SARah-3
|
2023-204_
|
24 December 2023
|
Falcon 9 Block 5
|
Vandenberg
SLC-4E
|
Success
|
Contractors
[
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]
Future
[
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]
A replacement of SAR-Lupe, called SARah, will be put into service from 2022. It will consist of 2 radar satellites and one optical satellite. The satellites of SARah will be bigger and more capable than those of SAR-Lupe.
[7]
SARah-1, a
phased-array-antenna
satellite, launched on
Falcon 9 Block 5
on 18 June 2022 and SARah-2 and SARah-3, passive-antenna synthetic aperture radars launched on Falcon 9 on 24 December 2023.
[8]
See also
[
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]
References
[
edit
]
- ^
SAR-Lupe ground station: Zentrum fur Nachrichtenwesen der
Bundeswehr
(ZNBw), Max-Planck-Str. 17, 53501 Gelsdorf
50°34′06″N
7°02′11″E
/
50.5683°N 7.0363°E
/
50.5683; 7.0363
.
- ^
a
b
c
d
"SAR-Lupe 1, 2, 3, 4, 5"
.
- ^
Stephen Clark (July 22, 2008).
"Radar reconnaissance spacecraft launched"
.
Spaceflight Now
. Retrieved
May 6,
2014
.
- ^
"Successful Launch Of Sar-lupe Satellite, With Thales Alenia Space's SAR Sensor Electronics Units"
(Press release). July 3, 2007. Archived from
the original
on May 6, 2014
. Retrieved
May 6,
2014
.
- ^
OHB-System AG (SAR-Lupe)
- ^
LSE Space Engineering & Operations AG
Archived
2006-10-24 at the
Wayback Machine
- ^
Nassauer, Otfried (26 June 2013).
"SARah: Bundeswehr will drei neue Spionagesatelliten kaufen"
.
Der Spiegel
.
- ^
"Deutsche Lastentransporte in den Weltraum"
(PDF)
(in German). January 21, 2019
. Retrieved
October 24,
2020
.