Hi Justin,
Just wanted to add a few things to your responses. Please see below.
Thanks,
Cordell

On 8/14/2015 3:58 PM, Justin Albert wrote:
> *** Discussion title: ALTAIR General
>
> CubeSats of the type described in the links you mention
> are certainly very interesting, but have three fundamental issues that
> would most likely prevent them from being used as high-precision
> calibration sources for the purposes we intend:
>
>    1) They are not launched into very accurately pre-determined orbits, and thus the chance that
>       a) such a CubeSat would be launched into an orbit that would be visible from observatories in, for
>          example, Hawaii or Chile -- or any major observatories anywhere -- and
>       b) remain in a useful orbit for a multi-year duration,
>       would be vanishingly small.
The orbit depends entirely on the launch that you choose. Many cubesats 
have been opting for launches that have low altitudes and sometimes low 
inclinations. As a result, their global coverage is poor and their 
lifetimes short.

However, there is nothing (but money) preventing those cubesats from 
going on a vehicle that is going into a more useful and long-lived sun 
synchronous orbit.
>
>     2) The PPOD picosatellite format of the type in the links above is truly tiny: a 10 cm cube with a
>        total power supply output maximum (when in daylight -- i.e. when it would not be useful to
>        us) of about 2 watts (and note that any batteries to store a useful amount of energy, plus of
>        course voltage regulator etc, would use up the majority of those space and weight limits,
>        leaving none for integrating sphere / light diffuser, light sources, calibrated photodiode, and
>        readout).
Completely agree. A cubesat is too small for this mission. As we've 
found there are some significant challenges even at 20cm per side.

-- 
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* Cordell Grant, M.A.Sc.
* Manager, Satellite Systems
* Space Flight Laboratory
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