[amsat-bb] Re: AO-7 Record
jamesduffey at comcast.net
Sat Jul 17 14:14:30 PDT 2010
On Jul 17, 2010, at 9:46 AM, Peter Portanova wrote:
> However, I can't think of too many satellites that have "come back to life" call it luck and possibly
> another force that also contributed to this marvelous piece of engineering
> to still be giving us enjoyment and world records!
Most commercial satellites are turned off or decommissioned when they reach the end of their useful life. In amateur radio, we operate under a different paradigm, that is we can and will use the space asset as long as it is viable. In the commercial world it is usually not economically viable to support an aging satellite when the assets can be applied to a newer satellite with more economic potential. That is why we seldom see commercial satellites come back to life.
In the amateur realm, I believe only RS10-RS11 have been turned off, and that was unintentional. Apparently it is irreversible. Others have deorbited.
There has been a significant change in the philosophy of what to do with aging and failed or failing satellites since AO-7 was launched. Early on pretty much a "who cares?" attitude dominated as satellites were left to fail and left in orbit. WIth orbital slots scarce these days and spectrum even scarcer, it is generally not considered good space engineering practice to let a spacecraft up to its own devices at the end of its life. It is considered good practice to ensure that the aging satellite will deorbit, or go into an orbit where it will not interfere with other active satellites. Although it is a great engineering feat to have our hardware still partially operational after 36 years in orbit, in some sense it is a bit embarrassing to have hardware in orbit that we cannot control. Fortunately, in AO-7s case the inability to control the satellite is largely benign.
One reason for decommissioning satellites is that rules governing their operation change over time. The 432 uplink for AO-7 now lies outside the WARC allocation for the Amateur Satellite Service, and it does not conform to the IARU band plan for satellite uplinks. The uplink is in the weak signal portion of the 70cm band, which is much more used these days than in 1974, and the uplink to AO-7 can cause a problem during high activity, such as 70cm.
We are fortunate to have another linear satellite to use, but we need to be mindful of the consequences of having a satellite in space that we cannot fully control. - Duffey
Cedar Crest NM
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