Alphasat's Champagne moment!
The party to celebrate the launch of our Alphasat telecommunication satellite on the 25th of July was great fun. Watching the live feed of the Ariane 5 rocket lifting-off majestically from French Guiana was a truly inspiring moment for everyone involved in this key project.
During the launch party, my colleagues and I re-lived some key moments from the Alphasat project, both positive and negative, as we architected, designed, built, tested, qualified, delivered, and integrated the payload – I remember helping to write the original proposal with my managers that we submitted to ESA back in 2004/05!
After we had developed and tested the prototype hardware in our Stevenage labs, we all moved to our Portsmouth cleanroom, 165 km south, to test and commission the qualification and flight-grade hardware. For many of my colleagues and me, this involved living in a hotel on Hayling Island for six months to two years.
The days were long and gruelling, but exciting, and during the winter months, the only daylight we ever saw was that during the short walk to the canteen at lunchtime. In fact, it was only last Christmas that I removed the emergency suitcase from the trunk of my car in case we received the dreaded phonecall, "Stevenage, we have a problem!" Several of the team then moved from Portsmouth to Toulouse in France, to assist with spacecraft-level testing and integration.
The spacecraft reached geo-stationary orbit last week requiring four burns of its apogee engine as well as consuming almost three tonnes of fuel to reach 36,000 km. Both its 40-m solar panels as well as its 11-m antenna reflector have been successfully deployed, and some of my colleagues are currently assisting Inmarsat to power-up the payload for initial in-orbit testing.
The spacecraft was developed as a result of a public-private partnership between ESA and Inmarsat and will live at 25°E in geostationary orbit covering Europe, Africa and the Middle East. The satellite weighed 6,605 kg at launch, has a size of 7.1 m x 2.5 m x 2.8 m, consumes 12 kW, and is illustrated below:
Alphasat is the most sophisticated and largest European telecommunication satellite ever built and some of its key technologies simply did not exist when we drafted the original proposal.
The mission's primary purpose is to offer flexible, mobile, communications making better use of an already congested L-band. The satellite supports over 400 spot beams processing more than 750 simultaneous channels for maritime, aeronautical and other mobile users. Forward and return links are supported simultaneously and the following video illustrates some of the communications capability:
The digital, beamforming processor provides unprecedented flexibility and operational capability in terms of routing, channelization and combining channels to the desired beam. The payload contains eight of these RF-DSP integrated processors, which are key elements for the generation of spot beams and associated channel gains. This provides Inmarsat with maximum flexibility in both frequency and power allocation to beams allowing it to meet traffic demands and optimize link budgets. The integrated processor developed by Astrium Ltd. is shown below.
The launch of Alphasat also represents the first flight of Alphabus, a new, high-capacity platform capable of supplying up to 22 kW of power, as well as supporting payloads up to 2000 kg providing a total spacecraft capability of 8800 kg. A video of the platform and how it mates with the payload can be viewed below:
The Alphasat payload does not use all the power generated by the solar panels and the spacecraft also includes four, smaller, technology-demonstration, hosted payloads as shown below. The secondary payloads include an optical communication terminal to relay data from LEO to GEO, a Q/V-band demonstrator, a star tracker, and a radiation monitor. The star tracker hosted payload was the first to be switched on to measure the spacecraft's attitude.
The Alphasat telecommunication satellite has significantly advanced the capability and expertise of everyone involved in this exciting project. In case you missed the launch, this can be viewed below:
The launch kit can be downloaded from the Arianespace website: "A Dual Launch for Mobile Communications and Meteorology Satellites" (PDF)
Two payloads were placed in orbit by the 70th Ariane 5 launch: Alphasat and INSAT-3D, the latter built and operated by ISRO.
On behalf of everyone at Astrium, I'd like to take this opportunity to thank all our partners: commercial, industrial, component, test, EDA, and many others, for helping to deliver the Alphasat telecommunication satellite to Inmarsat – you have all been Out-Of-This-World!
I'll be presenting a speech on the Alphasat Payload Processor at CERN's TWEPP in Italy next month. If you are in the audience, please come and say hi!
P.S. I'd like to credit Astrium and ESA for the photographs and videos used in this post.
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