On Jul 16, 2010, at 6:48 AM, Peter Portanova wrote:

Hello,

Congratulations, Joe and Luciano, on your outstanding, record-setting QSO! We must also give credit to the " Powers of the Heavens Above" who have kept AO-7 communicating with us!

The "Powers of the Heavens Above" do not keep AO-7 communicating with us. Careful and innovative design work, exhaustive parts selection for reliability, positive power budget, and meticulous attention to detail in fabrication 35 plus years ago made for a reliable bird. After failing due to a short in the battery cells, 20 some odd years of its own attempts to charge the battery and thermal cycling over 120,000 orbits opened the battery short and allowed the bird to transmit free form on its solar power only. There is nothing supernatural about it. Give credit where credit is due, to those who contributed to AO-7 conception, design, test, and construction: Jan King, W3GEY, Karl Meinzer, DJ4ZC, Werner Haas, DJ5KQ, Wallace Mercer W4RUD, Dick Daniels WA4DGU, Joe Kasser G3ZCZ/W3, Perry Klein, K3JTE, Tom Clark, W3IWI, Roy Soifer, W2RS, and Marie Marr. And to Drew, KO4MA, who has been coordinating satellite operations since it returned to service. - Duffey

-- James Duffey KK6MC, LM 1718 DM65tc Cedar Crest NM

Mr. Duffy,

I glad that you mentioned those individuals who made incredible sacrifices of their time and expertise to launch AO-7. 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!

73's Pete WB2OQQ www.massapequanyweather.com

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 -- KK6MC James Duffey Cedar Crest NM