Space blog

All five RapidEye satellites were successfully launched this morning by Dnepr from Baikonur, Kazakhstan.

Following this morning’s launch, the spacecraft separated from the launch vehicle in slightly different orbits to allow constellation phasing and will eventually be positioned equally spaced within the same orbit about 19 minutes apart. SSTL will control the constellation throughout the two week Launch and Early Operation Phase (LEOP) in a coordinated effort between their mission control facilities in the UK and the ground station supplied to RapidEye in Brandenburg, Germany. A team of three SSTL operators and three support staff will work with the MDA and RapidEye teams in Brandenburg, with the UK team analysing data as it is received and on standby to react to any technical challenges.

Project manager Ben Stocker commented: “The simultaneous launch of five satellites is not without its challenges. Commissioning will be performed from both the RapidEye ground station in Brandenburg and the SSTL mission control centre in Guildford. The five satellites will gradually disperse from each other following separation from the launch vehicle, allowing three satellites to be tracked and operated from Brandenburg with the remainder under the control of the Guildford operators. This method of operation offers the most efficient route to achieving the maximum amount of contact time per satellite during the early days of commissioning following launch. As the satellites are gradually manoeuvred into position around the orbit during the commissioning phase, the Brandenburg ground station will assume full control over the constellation.”

Following separation from the launch vehicle, the spacecraft activate three GaAs solar panels, generating up to 105W in sunlight. The power system will then assume active control of the battery charge management system, enabling operators to initiate communication with the five RapidEye satellites via the S-band system. Within hours the team plan to upload programs to the on-board computers that will enable early operations and checkout to commence.

The attitude control system on each spacecraft will use magnetometers, magnetorquers, sun sensors and reaction wheels to achieve 3-axis stabilization, whilst using high accuracy attitude information from a star camera to finalise accurate nadir (towards Earth) pointing before proceeding with more advanced roll manoeuvres.

Following LEOP, the full functionality of the satellites, including the imaging payloads built by German company Jena-Optronik GmbH, will be tested by collecting imagery over a 10-week period. During this time MDA will demonstrate the performance of the constellation before RapidEye AG takes delivery of the system and commences commercial imaging operations.

RapidEye plans to operate the mission to deliver agricultural land information products and services such as crop monitoring and mapping, yield prediction and natural disaster assessment.

SSTL’s Chairman, Sir Martin Sweeting, commented: “SSTL long ago established the benefits of small satellite constellations and launched the Disaster Monitoring Constellation in 2002, paving the way for a new paradigm in remote sensing. The launch of RapidEye will fully realise the business potential of constellations.

The simultaneous build of five satellites is the largest mission so far in terms of maximising and managing production at SSTL’s Guildford facilities. Expert in-house engineering and project management teams worked closely with MDA, streamlining the design, build and test of all five satellite platforms.”

SSTL has won a contract worth €1.6 million from Astrium GmbH, Germany to proceed with work on a new contract to develop and supply the Multi-Spectral Imager (MSI) for the European Space Agency’s (ESA) EarthCARE Mission.

Earth Explorer Missions are part of the Earth Observation Envelope Programme (EOEP). They are missions led by the European Space Agency to address primary research objectives. The EarthCARE Mission has been approved for implementation as the third Earth Explorer Core Mission. The mission will be implemented in collaboration with Japanese Aerospace Exploration Agency who will provide one of the core Instruments. The EarthCARE mission has been specifically defined with the basic objective of improving the understanding of cloud-aerosol-radiation interactions so as to include them correctly and reliably in climate and numerical weather prediction models.

The EarthCARE mission aims to improve the understanding of the Earth's radiation balance and to minimize uncertainties in climate change prediction models by acquiring accurate vertical profiles of clouds and aerosols, as well as measurements of top of the atmosphere radiance. The Multi Spectral Imager produced by SSTL will provide information on the horizontal structures of clouds, such as cloud type and cover, and cloud optical and microphysical properties. The instrument's 150 km swath will be used to extend to three dimensions the validity of the aerosol, cloud and radiance measurements made by the active EarthCARE instruments which are all directed towards the satellite ground track.

This contract is for the first stage of the Phase B design study; the full Phase B is a 15 month programme. This will be followed by a Phase C/D leading to mission launch in 2013. SSTL is supported in the MSI programme by TNO from The Netherlands who are acting as subcontractors to SSTL.

This may sound like a familiar joke - but for the 5 RapidEye spacecraft built by SSTL a fit-check is an important preparation before the ultimate launch. The SSTL and MDA (the prime) launch teams visited the KB Yuznoye works at Dnepropetrovsk, April 14th – 18th, to conduct a spacecraft fit-check with the Dnepr launch vehicle.

Fit-check is an important event in the launch schedule as its purpose is to technically clear the way for successful integration of the flight spacecraft at the Cosmodrome.

The fit-check established that all the physical interfaces between the spacecraft and the launch vehicle were correct. During meetings, the launch teams were able to qualify the actual route of integration – an especially important activity when, as in this case, five spacecraft are being launched on a single launch vehicle.

So the answer, dear Space Blog reader is 5 - or at least 5 RapidEye spacecraft.

DMC International Imaging was on regular 24/7 duty as the Emergency On-Call Officer (ECO) for the International Charter; Space & Major Disasters from 21st to 28th January 2008. Gary Crowley, DMCii Operations Manager, coordinated the scheduling of images from DMC satellites as well as Envisat, Radarsat, ALOS, SPOT-5, IRS (Pan & LISS-3), Ikonos and QuickBird, for the Charter response to two disaster activation calls.

Last Tuesday (22nd January) DMCii monitored a volcanic eruption in Ecuador. The images below are by kind permission of NASRDA.



Just last Friday (25th January) the International Charter was activated to image flooding in Bolivia.