From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lang.hm (syn-045-059-245-186.biz.spectrum.com [45.59.245.186]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 0725E3B2A4 for ; Wed, 4 Sep 2024 20:07:36 -0400 (EDT) Received: from dlang-mobile (unknown [10.2.3.133]) by mail.lang.hm (Postfix) with ESMTP id 280F71DE51D; Wed, 4 Sep 2024 17:07:36 -0700 (PDT) Date: Wed, 4 Sep 2024 17:07:36 -0700 (PDT) From: David Lang To: David Lang cc: Brandon Butterworth , Dave Taht via Starlink In-Reply-To: <4n7s5s50-12n0-n4q4-3978-0qr743n043o9@ynat.uz> Message-ID: <3so90614-s27r-21qn-p1p1-1q7n5798193s@ynat.uz> References: <4n7s5s50-12n0-n4q4-3978-0qr743n043o9@ynat.uz> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Subject: Re: [Starlink] lumen orbit X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Sep 2024 00:07:37 -0000 David Lang via Starlink wrote: > On Wed, 4 Sep 2024, Brandon Butterworth via Starlink wrote: > >> On 04/09/2024 15:48:51, "Dave Taht via Starlink" >> wrote: >>> They plan to build a 5GW 4k solar square for data centers in orbit, >>> launched on starship: >>> >>> https://www.lumenorbit.com/ >> >> Maintenance call outs are going to be interesting >> >>> How are they going to cool this thing? >> >> With some big radiators. From >> > https://www.nasa.gov/wp-content/uploads/2021/02/473486main_iss_atcs_overview.pdf >> >> it seems that the ISS units take about 23 * 3.5m area for 35kW so >> about 440 W/m^2, if they are about the same then 5GW will need >> around 11 million sq metres. >> >> That seems a totally unfeasible number so either I messed up the >> calculation, or they have way more efficient radiators than NASA, >> or this is wishful thinking/investor grift. > > the efficiency of radiators goes up drastically as the temperature of the > radiator goes up (there is a T^4 factor in the equasion, T in kelvin) so if > they > can get the coolant hot enough, they can shrink the radiator area by > increasing > the temp. > > but since 0c = ~273K, running the temp up to just over the melting > point of aluminum would let you get to about 1000x efficiency for the > radiators > (@1255c) but would still need a massive radiator. 11k sq meters is still a > lot. > the ISS radiators are a little of 6Kg/sq meter, so you are up to around 70T > worth of radiators (possible with a starship, but still massive) > > designing a heat pump that can pump heat from chips into molten aluminum is > left > as an excercise for the reader :-) correction, sloppy reading (F vs C), molten aluminum is only 660c, to get the 1000x efficiency, you would be up to the temp of molten iron. just don't let if freeze in the pipes :-) David Lang