This allowed Envisat to provide a detailed map of the ground displacements following the disastrous earthquake in Japan in March 2011. 35). - Since April 2006, the instrument performance is regarded as “fair”, the radiometric and spectral performance is regarded as excellent. ASAR ScanSAR modes (Alternating polarization, Wide swath, and Global monitoring) [8][9] Ground-based radar and the French Pleiades Earth probe were used to image the silent Envisat and look for damage. Both the satellite size (26 m x 10 m x 5 m, 8000 kg) and the number of on-board sensors are unique. - Time per elevation scan - Ocean: monitoring marine biophysical and biochemical parameters (chlorophyll, gelbstoff concentrations, suspended particles). 109), Figure 55: Global mean increase in atmospheric CO2 between 2003 and 2009 (image credit: O. Schneising & M. Buchwitz, IUP, University of Bremen), • SCIAMACHY's current performance (2009) fully supports the extension of the EnviSat mission until 2010.

Perigee: 783 km (486 mi). 26 m (85 ft) × 10 m (33 ft) × 5 m (16 ft) in orbit with the solar array deployed. selectable in range from 0.035 - 0.35 cm-1, Radiometric parameters

The performance of the Steering Front Mechanism of the redundant side degraded since January 2005, due to the malfunctioning of the Telescope Elevation Drive. Background: Originally, two parallel and staggered mission series were proposed in the POEM program. 0.66 µm - The output signal (interferogram) enters the focal-plane subsystem where beam size matching, beam splitting and optical filtering is performed. - Band center knowledge, 0.39 - 1.04 µm (VNIR) - Monitoring natural and man-made pollution over the oceans. Global survey of related stratospheric trace gases (NO2, NO3, H2O), aerosols and temperature. AATSR features two 500 km wide curved swaths, with 555 pixels across the nadir swath and 371 pixels across the forward swath. - IFOV Then, 150 seconds later, or when the satellite has moved by about 1000 km forward along the ground track, a second observation is made of the same scene at the subsatellite point (see Figure 51). 1441-1443, Hamburg, Germany, June 28 - July 2, 1999, 71) “ASAR Advanced Synthetic Aperture Radar,” ESA brochure, 72) http://envisat.esa.int/instruments/asar/, 73) http://envisat.esa.int/handbooks/asar/CNTR3.htm#eph.asar.instr, 74) S. Karnevi, E. Dean, D. J. Q. Carter, S. S. Hartley, “Envisat's Advanced Synthetic Aperture Radar: ASAR,” ESA Bulletin, No. 35). 60, 1998. MERIS (MEdium Resolution Imaging Spectrometer) measures the reflectance of the Earth (surface and atmosphere) in the solar spectral range (390 to 1040 nm) and transmits 15 spectral bands back to the ground segment. 2, pp. Data gap actions will very partially compensate for the lack of Envisat data, i.e.

Envisat’s instruments were slowly switched back on starting on 27 October, and the satellite is now gradually resuming its normal activities. • Chemistry of the stratosphere: O3 (global and polar), NO, NO2, HNO3, HNO4, N2O5, ClONO2, COF2, HOCl. 11-21, URL: http://www.esa.int/esapub/bulletin/bullet105/bul105_1.pdf, 101) M. Gottwald, H. Bovensmann, G. Lichtenberg, S. Noel, A. von Bargen, S. Slijkhuis, A. Piters, R. Hoogeveen, C. von Savigny, M. Buchwitz, A. Kokhanovsky, A. Richter, A. Rozanov, T. Holzer-Popp, K. Bramstedt, J.-C. Lambert, J. Skupin, F. Wittrock, H. Schrijver, J. P. Burrows: “SCIAMACHY, Monitoring the Changing Earth's Atmosphere,” Published by DLR, 2006, http://atmos.caf.dlr.de/projects/scops/sciamachy_book/sciamachy_book.html, 102) http://www.iup.uni-bremen.de/sciamachy/instrument/index.html, 103) A. P. H. Goede, H, Schrijver, “SCIAMACHY: An Atmospheric Chemistry Instrument on ENVISAT,” Proceedings of IGARSS'99, Hamburg, Vol. GOMOS was built by EADS Astrium SAS (formerly MMS), France. 100), 0.55 µm • Sixteen thrusters, 8 allocated to each nominal and redundant actuator chains.

In 2010, the orbit was modified into a 30-day cycle to further extend the mission lifetime with the objective of providing a bridge to the Copernicus Sentinel missions (Sentinel-1, Sentinel-3 and Sentinel-5P). 25.8 kg on average per year). It measures the radar backscatter of the Earth's surface at C-band with a choice of five polarization modes: VV, HH, VV/HH, HV/HH, or VH/VV. The transmit pulse characteristics are: the output is a linear FM up-chirp pulse centered at 124 MHz of the IF carrier. Depending on the optical path difference in the two interferometer arms, the recombined signal is an intensity-modulated interferogram. Since then, the MIPAS instrument has been operated at reduced spectral resolution for tests in August and in December 2004. ESA is trying to reduce the impact of the data gap with two types of initiatives: 19). Local services are also offered to internal users.

20 nm The diffuser provides a reflectance standard across the entire spectral range and FOV. The propulsion module on top of the cone contains four tanks, which hold over 300 kg of hydrazine. In the optical assembly the radiation from the atmosphere is fed by the scanner (consisting of an azimuth and an elevation scanner) into the telescope which directs it onto the entrance slit of the spectrometer. 28) 29), • In the summer of 2011, Envisat is fully operational in its new orbit configuration (30-day repeat cycle) implemented since October 2010. [The Michelson interferometer provides an unapodized spectral resolution of better than 0.035 cm-1 throughout the spectral range. Figure 52: SCIAMACHY detector modules (single detector left, 8 detector modules at right), image credit: SRON), Table 13: Spectral parameters of SCIAMACHY, Figure 53: Optical concept of the SCIAMACHY double spectrometer, Figure 54: Optical arrangement of the SCIAMACHY instrument (image credit: University of Bremen).

The system transmits pulses to and receives echoes from a sub-swath for a period long enough to synthesize a radar image of the area within the beam footprint at the required resolution. As part of that rescue effort, ESA officials asked their international partners for aid in investigating the giant satellite's malfunction, and the French space agency CNES volunteered time with its new Pleiades spacecraft. • A spatial-spread monitoring mode, allowing optimization of position of the CCD read-out regions with respect to that of the stellar spectrum. The new orbit scenario is characterized as follows (Figure 22): - Milestone II : In October 2010 the Envisat orbit is lowered by 17.4 km without changing the inclination of 98.549º (estimated hydrazine consumption : 34 kg).