From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x232.google.com (mail-lf0-x232.google.com [IPv6:2a00:1450:4010:c07::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id E4E423CB43 for ; Tue, 13 Mar 2018 21:49:36 -0400 (EDT) Received: by mail-lf0-x232.google.com with SMTP id q69-v6so2315511lfi.10 for ; Tue, 13 Mar 2018 18:49:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=EhV7Wf9n964vl2T2feZdo6MZJJd/684fjEDkgIA8af8=; b=lsIcFcH5hDnHIA2E5sodk1DYUYU+8VSFCoN4YiCPDYd6R+TDv0Pv3crFdS1mMq9cJD Jsnzm3sxy0D7SUS+DospZiqyXsb4ny4HZwNd+tZpS/UtQ+0roWHNxr50+Zf8gUP1jSXa gLUF3b8DM8TnyeaHNF2fguBduY41rdmVT4qb7eCF4dUReew24xmD2M56No3tjpAG3DYp vK2gaDzB3nood1hy79qAJdTz1uRjovnMJHXAtHG2C9nMFXsHnmf5A35Lg9o8Eq94FHG5 OVxk7xn/bG4xs/zWuUFKWQBZ/pF5edCbqWIwzhtL0ier+wxywyqkeS75WpdNTOrxf6jZ CDJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=EhV7Wf9n964vl2T2feZdo6MZJJd/684fjEDkgIA8af8=; b=HojK09Rgjwr327a6Y798VGwaSPsNpy60aK+tYen2KoSCkW/LUDIEVr+CHTVa1CK5S4 uAdiOlaMUMFBHZpod4K2XMgDMcI8oMI3Dx1g0Cnb75sQu1Ia/3ovqQLUxSAHb3niFARD ymVDPgHuqdOFg7tSmU6pjPeOVqSV2NxoIXGXfYkxg2pbAxdDCbe0HeSUCkmgZUUyODVW rwk4wcl1sgqqZAleflQzVij9eoJbFzslh/nazDVaxRQa1XlHRIgk0VrAICIVmlBFSHc6 PQpSbDfS3DweWf4NAr4/16pUvsWdotW9r6vw1bvubshKyUrC7xfT/ud/Y0ltqQtMYqB4 jqPQ== X-Gm-Message-State: AElRT7GyQp5zZkqYHov2z9dvp1AqlkXKPCxhs4r6h3kdbA4YEtPs5v4s cYrh5acOkHnu0+1qa6W1FTw= X-Google-Smtp-Source: AG47ELu/g/V1+tki17b8xnydW4FBUoGtMWl38mPZPx0flgpQDa9/bm9OOT7vQCOyC+v7lWcy3T+aSA== X-Received: by 2002:a19:7103:: with SMTP id m3-v6mr1924911lfc.29.1520992175823; Tue, 13 Mar 2018 18:49:35 -0700 (PDT) Received: from [192.168.239.216] (83-245-237-207-nat-p.elisa-mobile.fi. [83.245.237.207]) by smtp.gmail.com with ESMTPSA id r26sm340239ljc.8.2018.03.13.18.49.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Mar 2018 18:49:34 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.2 \(3445.5.20\)) From: Jonathan Morton In-Reply-To: Date: Wed, 14 Mar 2018 03:49:32 +0200 Cc: Jim Gettys , cerowrt-devel@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: References: <1520875105.31683592@apps.rackspace.com> <1520881804.31539998@apps.rackspace.com> To: Dave Taht X-Mailer: Apple Mail (2.3445.5.20) Subject: Re: [Cerowrt-devel] spacebee X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Mar 2018 01:49:37 -0000 > On 13 Mar, 2018, at 7:31 pm, Dave Taht wrote: >=20 >> Size, until the object gets really small, really doesn't matter. >=20 > The odds of a collision drop proportionally (what's the math?) to > size. Imagine useful sats this small, or smaller, in lower orbits that > burn up in a few years, and constant replacement and technological > refreshment... Observation: we're talking about an object that's substantially bigger = than a bullet, substantially heavier than a bullet, and travelling = *faster* than a bullet. Collisions with such an object would be = extremely high-energy, and spacecraft don't have the weight budget for = the tank-grade armour required to survive such an impact. I don't think the occupants of the ISS would be very happy with being = hit by a titanium cricket ball at 10,000 kph relative. Also, the probability of collision, given random trajectories, depends = on the sizes of *both* objects involved - and rather more strongly on = the size of the *larger* object. If you reduce the size of a 10cm = object by 50%, it has much less effect on the combined collision radius = than reducing the size of a 10m object by 50%. - Jonathan Morton