[LMB] Arecibo

Markus Baur baur at chello.at
Mon Nov 23 21:20:46 GMT 2020


snippitites est .. answer inline

Am 23.11.2020 um 21:53 schrieb Marc Wilson:
> On Mon, 23 Nov 2020 20:26:27 +0100, Markus Baur via Lois-Bujold
> <lois-bujold at lists.herald.co.uk> wrote:
>
> Am 23.11.2020 um 19:07 schrieb WalterStuartBushell:
>>> More feasible would put it in low Earth orbit, where there is
>>> radiation protection from the Earth’s magnetic field,
>>> and it can scan more of the sky.
>> yes - it can scan a lot more of the sky .. but you also get  the full
>> dose of earth's radio noise .. putting the telescope on the far side of
>> the moon will cut down on the noise by an absolutely HUGE amount
>>
>> also - it can look at one spot of the sky only at aa time .. but
>> observations are planned a long time ahead - so having to wait 14 days
>> to be able to see the "other side" of the sky usually is not a big burden
>>
>> the long planning ahead also makes the 2 to 3 second communications
>> delay from / to the far side not a big problem .. only if you absolutely
>> need to hold a real time conversation, and even there 2-3 seconds are
>> manageable
>>
>> the logistics of building and maintainnig the telescope will be made
>> easier in LEO yes ..
>>
>> the radiation however will be a lesser problem - lunar regolith is a
>> nice radio shield, but also a good radiation shield (the habitat for the
>> building and maintenance crew will be below the surface)
> How about the L2 point?

https://i.imgur.com/WGOy3qT.png

L2 is an interesting idea ..

compared with the lunar surface it has the advantage of a markedly lower 
dV - by about 2.5 km/s ... a huge advantage in terms of logistics and cost

if you can make the halo orbit around L2 narrow enough the bulk of the 
moon should shield most if earth's radio noise - but i am not sure that 
there will not be edge effects with radio noise grazing the moon's limb 
and "bending" around the moon, so we might need an additional shielding 
against radio (with the mass and costs that would produce) - 
construction and maintenance habitat would also need additional 
shielding as you cannot use local regolith for that

servus

markus



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