[Server-sky] S band versus phone

Keith Lofstrom keithl at gate.kl-ic.com
Wed Jul 3 12:49:53 UTC 2013

On Tue, Jul 02, 2013 at 03:22:30PM +0900, Michael Turner wrote:
> It's been proposed (sorry for the vagueness, there's some ITAR
> sensitivity here from my source) that PhoneSat become a kind of
> standard cubesat bus. It will lack S-band of course but will have a
> camera and bluetooth.

My interest in S band is that the space station software radio is
a ram-facing agile system that has the bandwidth to collect lots
of video data.  I've been swapping emails with Jim Lux, the co-P.I.
at JPL, about this.


To do the experiment I have in mind, we need to release into a
near-circular orbit - an apogee below ISS will have way too much
ram drag.  As it is, there will only be a few orbits (20? WAG)
before the orbit decays down into the high drag zone, and perhaps
50 more before reentry.  

The way the orbital mechanics works is that when an object is
"slowed" by drag, it drops into a lower orbit and revolves faster.
Relative to the launch point, it drops and appears to accelerate
forwards in the "ram" direction.  So the SCaN radio is pointed 
the right way, and the data collection systems are available to
downlink our data (a lot of video).    

> The "tent" could double as a de-orbiting mechanism later in flight.
> There's been some persuasive talk of a standard for deorbiting cubesat
> using this technique
>    http://repository.tudelft.nl/view/ir/uuid%3A49d86db1-8909-4464-af1b-fe1655c9c376/
> If there could at least be an option in the standard for tent-fabric
> transparency, there might be other space-sci/tech uses for it, by
> other researchers who'd like long-duration nanogravity themselves,
> together with solar insolation. Well, OK, maybe only other solar-sail
> researchers. But still.

That is good thinking.  There are many other research projects that can
use this;  if the tent is "evacuation pumped" to the rear, it recreates
conditions at higher altitudes for many different experiments, as well
as the insolation and black body characteristics at the high altitudes
if transparent.  

There is a business here.  A lot of researchers will just want to run
their experiments without worrying about all the complications of
managing a cubesat. 

There is already a precedent;  the US Naval Academy offers an
experimental compartment in a 2U cubesat to outside experimenters.
Plug your "sub-cube" into theirs, and they will provide power and
communication and mission control.  This is for cadet training;
these will soon be the officers who manage the Navy's space assets.


P.S. on the "Drag" web page, I show altitudes for the Virgin Galactic
spaceship 1 and 2 on the graph.  As Michael points out, those aren't
orbital, they move far slower and the drag is much less.  I should
redraw the graph with those points far below the line.  Or better yet,
I should attach sources and let one of you redraw it.

Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993

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