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RazakSat, formerly known as MACSat, was originally scheduled to fly on the third Falcon 1, in 2006 or 2007. Its launch was delayed after several previous launches failed, but following the Falcon 1’s successful test flight last September, it is finally ready to fly.

Once the demonstration flight was completed, the RazakSat launch was scheduled for early 2009. However, just a few days before a scheduled launch attempt on 20 April, the launch was postponed due to excessive vibrations.

A mitigation system was installed in the payload adaptor, but in order to allow this to be installed, two CubeSats – which were originally scheduled to have been launched as secondary payloads – were removed. It is currently unclear if and when these spacecraft, named CubeSAT and InnoSAT, will be launched in the near future.

RazakSat was built by the Satrec Initiative and ATSB, using an SI-200 bus. It will be the first SI-200 to be launched, with the second, DubaiSat 1, currently scheduled to fly aboard a Dnepr on 25 July. It has a mass of 180 kilograms, and is expected to operate for at least three years.

Its primary mission is electro-optical Earth imaging, however it will also be used for technology demonstration and weather research. Its main instrument, the Medium-sized Aperture Camera (MAC), is designed to capture images with a resolution of 2.5 to 5 metres.

The Falcon 1 is 21 metres tall, with a diameter of 1.7 metres, and a mass of 27.67 tonnes. The first stage of the Falcon 1 is powered by a Merlin-1C engine, which will deliver 347 kilonewtons of thrust at liftoff. It will burn for about 169 seconds, propelling the rocket to an altitude of around 90 kilometres.

The first stage will then shut down, and a few seconds later it will separate by means of a pneumatic system. The first stage was designed to be recovered by parachute for reuse, however this is yet to be demonstrated. First stage recovery is not believed to be planned for today’s launch.

The second stage is propelled by a single Kestrel engine, delivering 31 kilonewtons of thrust. It will deploy RazakSAT into a circular orbit with an altitude of 685 kilometres, and nine degrees of inclination.

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.

Tree Topology

Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.