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Light Up the Sky – With Your Radio

LightCube CubeSat

The planned launch of LightCube, a CubeSat, will be the latest man-made object in the sky that will flash on command. The command will be a coded radio transmission sent from something as simple as your handheld operating in the licensed Ham bands. The bright Xeon Strobe should be visible from the ground letting you know that your radio triggered it.

The first satellite built for use by Amateur Radio Operators was called Oscar 1 and was launched in December 1961. I would have been 6 years old, and this was just 4 years after the first ever man-made object transmitting from space Sputnik 1. This gives some perspective on how quickly this technology was developing. Oscar 1 weighed 22lb and was 6" by 10" by 13". It transmitted on the 2M band with 140mW. It broadcast the CW signal "HI" for about three weeks before falling silent.

Compare that first launch to SMOG-1 (Magyar-OSCAR 110), which was launched in March of 2021. It is the first functioning PocketQube satellite, the size of a 2" cube and under 9oz. The telemetry frequency is 437.345 MHz with callsign HA5BME and can be decoded using a Raspberry PI with an SDR.

The latest launch I could find was on June 22, 2021, MIR-SAT1 was deployed from the International Space Station. It was designated MIRSAT-OSCAR112. This is a bigger CubeSat (4" cube) and uses an Uplink of 145.988MHz and Downlink of 436.925MHz. It was given a "free launch" which is often offered to these small payloads. Its stated goals in order are: 1- Performance of its technology, 2 – Collect images of the Rep of Mauritius, 3 – Experimental communications with other Islands useful for emergency purposes.

Most of the Amateur Satellites get placed in low earth orbit which means they spin round the earth at high speed. They rise and fall in the sky in a predictable way typically remaining in range of a fixed point for around 10minutes (highly dependent on specific tracks). This means that continuous operation through one satellite would not be practicable, you would need to constantly switch as they come into and out of range. Although this sounds complicated it the basis of how Starlink operates.

Commercial satellites, such as those providing TV service, circle the earth in a Geostationary orbit. This has to be much further away from the earth but means that their orbit matches the rotation of the earth, so they appear stationary from the ground. These do provide reliable 24/7 communications, at the expense of needing more power and operation at higher frequencies. Typically, a microware dish antenna is needed.

There are a few Geostationary Amateur Radio satellites in operation. Es'hail-2 launched in 2018 has transponders for use by Amateurs.They operate on 2.4GHz and 10.5GHz for narrowband linear signals (SSB) and wideband digital including TV.

Much of the motivation to develop and launch Amateur Satellites is driven by the desire to explore the possibility of building them with pioneering circuit design and communicating using the less proven digital techniques. Satellites have already been demonstrated as capable of passing messages in a simulated emergency and for public events. With the ever-increasing launch frequency and geostationary orbits, they could become part of an Emergency Ham Network? But for now, keep an eye out for LightCube and send your own message from the Sky.

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Wednesday, 24 July 2024