Space blog

From its Guildford headquarters SSTL design and manufacture small satellites, subsystems and optical equipment for missions in Low Earth Orbit (LEO), Geostationary Earth Orbit (GEO) and interplanetary missions to the Moon and beyond. These capabilities wil be on show at the IAC from 29 September to 3 October, with representation across its projects, engineering and business development teams, who will present 16 papers throughout course of the week.

The SSTL team will be on-hand to answer questions about small satellites and their wide-ranging application in our daily lives, which include communications and Earth observation. If you are interested in a career in the space industry, you can also discuss opportunities to join the company’s growing team in Guildford and Sevenoaks.

IAC 2008 will take place at the Scottish Exhibition and Conference Centre , situated on the banks of the River Clyde in Glasgow. It will provide an international focus for the global space industry, academic researchers and students worldwide through the presentation of the latest ideas, current activities and future ambitions across a diverse range of space-related topics.

The long awaited results of the UK Space Competition, brainchild of SSTL's Dr. Stuart Eves will also be announced at the event. The winning school team will receive assistance from SSTL to develop their experiment which and launch it into space enabled by £100,000 British National Space Centre (BNSC) sponsorship.

The city of Glasgow is an important international centre for business, education and the arts and provides an excellent meeting place, mid-way between West and East, to host the exchange of ideas and stimulation of new concepts by participants from all nations through a combination of technical sessions, social and outreach events.

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.