XPost: rec.radio.shortwave
From: bit_bucket@gmx.com
On 11/13/2011 2:19 PM, Lord Valve wrote:
> John Smith wrote:
>
>> On 11/13/2011 10:25 AM, Lord Valve wrote:
>>> Don Pearce wrote:
>>>
>>>> On Sun, 13 Nov 2011 08:38:28 -0700, Lord Valve
>>>> wrote:
>>>>
>>>>> dave wrote:
>>>>>
>>>>>> On Sun, 13 Nov 2011 11:39:03 +0000, Geoffrey S. Mendelson wrote:
>>>>>>
>>>>>>>> It is much more important to know exactly how long and how well your
>>>>>>>> satellite is going to work than to hope to get longer by using a
>>>>>>>> technology that might last longer, but will more probably die
>>>>>>>> unexpectedly when struck by a cosmic ray burst.
>>>>>>>
>>>>>>> Sometimes you can not predict how long a satellite will be used. A
>>>>>>> friend of mine worked on a civilian satellite for a defense contractor
>>>>>>> and just before the division was sold off, cleaned out any old
documents
>>>>>>> and files they had on it.
>>>>>>>
>>>>>>> Since the satellite he had worked on was way past its expected life
(but
>>>>>>> still in use), the contracts had long expired, the work was not
>>>>>>> classified and a new improved one was due to be launched in a few days,
>>>>>>> he was told to dump it all.
>>>>>>>
>>>>>>> A few days later, the booster exploded on the pad, and the replacement
>>>>>>> was destroyed.
>>>>>>>
>>>>>>> The sattelite was kept running for many years, although there were no
>>>>>>> documents on what to do or how it was built.
>>>>>>>
>>>>>>> Geoff.
>>>>>>
>>>>>> What good is a diagram if the unit is 24,000 miles in the air?
>>>>>
>>>>> It had better *not* be in the air... ;-)
>>>>>
>>>>> Besides - I saw mention upthread of using the ambient
>>>>> vacuum with just the tube elements, rather than a typical
>>>>> evacuated glass (or other material) enclosure...is the
>>>>> vacuum in geosynchronous orbit really hard enough?
>>>>> It would seem to me that there are probably plenty of
>>>>> gas molecules floating around at that height, even if
>>>>> it would still qualify as a "soft" vacuum. Anybody?
>>>>>
>>>>> Lord Valve
>>>>>
>>>>>
>>>>
>>>> For all sorts of other reasons, standard enclosed tubes are used. Main
>>>> reasons are first to contain the electrons so other metalwork doesn't
>>>> get involved, and second to maintain the correct physical positioning.
>>>> The helix is of very fine tolerance in both pitch and positioning.
>>>> Space is certainly hard enough, but the environment around a satellite
>>>> is frequently not space, but a diffuse cloud of exhaust gas which
>>>> would extinguish a TWT immediately.
>>>>
>>>> d
>>>
>>> Ah. Good point!
>>>
>>> Satellites do indeed need to use propellant of some sort
>>> to keep in position; I didn't think of that at all. And it
>>> would seem that even if the ambient vacuum were
>>> hard enough, conventional construction of the TWT
>>> would be needed to keep contaminants out of it during
>>> the satellite assembly process down on Terra firma.
>>> But I must admit, the idea of using ambient vacuum
>>> tickles my fancy a bit. ;-)
>>>
>>> Lord Valve
>>>
>>>
>>>
>>
>> I don't recall anyone ever claiming there was no enclose on the devices
>> ... just the reasons for enclosing them the way we do on earth is now
>> gone ...
>>
>> Regards,
>> JS
>
> Do you actually read this shit, or have you been into the medicine cabinet?
>
>
> Lord Valve
>
>
>
I usually don't read imbecilic stuff ... such as yours. But, if I do, I
certainly do not take it seriously ... perhaps you will have better luck
with others.
Regards,
JS
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