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.”

Since our last update How many spacecraft can you fit in a Dnepr? regarding the 5 RapidEye fit-check in Baikonur, an MDA / SSTL launch team set to work in July preparing the small satellite constellation for launch.

All five RapidEye satellites have now been been integrated with the Dnepr launch vehicle at the Baikonur Cosmodrome in Kazakhstan and are ready for launch at 0715 UTC (0815 BST, 0915 CEST) this Friday (29th August).

SSTL designed, built the spacecraft bus and performed the assembly, integration and test its facilities in Guildford, UK. It also supplied the spacecraft control centre. MDA’s subcontractor Jena-Optronik GmbH of Jena, Germany, designed and built the imaging payloads.

MDA is the prime contractor of the RapidEye mission that is delivered turnkey and in-orbit to RapidEye AG. MDA has direct responsibility for the mission design, the spacecraft design and the ground planning and image processing system. The Canadian Commercial Corporation, a Government of Canada Crown corporation, is acting as the contracting agency between MDA and RapidEye AG.

RapidEye is a commercial small satellite mission that will enable global monitoring of the Earth’s surface. The constellation is designed to provide insurance and food companies, farmers, government and other agencies and institutions throughout the world with valuable, up-to-date, customised information products and services of the highest quality.

The dedicated launch will place the five satellites in a common sun-synchronous orbit of 630 km, with the satellites equally spaced about 19 minutes apart in their orbit, ensuring frequent imaging of particular areas of interests.

The RapidEye system will image any area in the world at all latitudes between +/- 75 degrees within one day and cover the entire agricultural areas of North America and Europe within an average of five days. The multi-spectral pushbroom style imager onboard each spacecraft will image the Earth in five spectral bands, scanning a 78 km swath at 6.5m resolution.

SSTL has just signed up to an interesting study under ESA's Project for On-Board Autonomy (Proba) with Spanish company Deimos. The PROBA-IP study will investigate a mission to perform in-orbit validation of technologies required to reduce the operations costs of Solar System exploration missions and to enable Near Earth Object (NEO) characterisation missions.

Near-Earth Objects (NEOs) are comets and asteroids that have orbits that allow them to come into close proximity with the Earth. They are mostly composed of water ice embedded with dust particles. They attract some scientific interest because they have remained relatively unchanged since the formation of the solar system 4.6 billion years ago.

The PROBA-IP mission concept is also intended to demonstrate micro and mini-spacecraft capabilities in the interplanetary mission domain. This is already an area of focus within SSTL because of its involvement with low cost lunar exploration under the NASA / MSU Magnolia mission experiments.

The study is led by Deimos, whilst SSTL is investigating the platform design and the spacecraft Failure, Detection, Isolation and Recovery (FDIR) concept. FDIR is an increasingly important part of small satellite design because functionality previously implemented in hardware is often replaced by on-board software.

Fail-safe and fail-over systems and FDIR are an essential part of modern small satellite design. Satellite failure, no matter what architecture is always a risk in space missions - particularly in the unknown environments that could be encountered during interplanetary exploration and the risk must be managed.

During the study with Deimos, SSTL will draw upon its 27 mission heritage in developing and defining software architectures that support FDIR functions to guarantee dependable and autonomous systems in space that are suitable for interplanetary exploration.

The Space Experiment Competition is now approaching the final, which will be held at the IAF congress in Glasgow on 3 October. Six teams have been downselected to compete for the pize of flying their experiment on an SSTL mission in the 2010 timeframe, and all six have now had the chance to visit SSTL and take a tour of our clean-room.

Indisputably the most entertaining question we were asked during these tours was

"Do you have a 'No Farting' rule in the clean room?"

...we're still trying to think of an appropriate response!

At BNSC's invitation, the teams have also had the opportunity to attend the Farnborough international airshow and present their experiments to Science Minister Ian Pearson, who expressed his admiration for the high quality of the science that the teams were hoping to do. All the teams were presented with copies of the book "BANG!" as a momento of their participation in the competition.

The teams have until September 12th to finalise their designs and submit them to the judging panel, which includes Colin Pillinger of the Open University, Pallab Ghosh the BBC's Science Correspondent, and Keith Mans the president of the Royal Aeronautical Society.

Further information can be found at www.spaceexperiment.info, and the BBC have also been following the competition (see Space experiment contest launched, Six teams vie for satellite prize) aswell as industry well wishers SatNews (SSTL Pumps Up Students With Awesome Sat Creation Contest)