Thanks for the extremely useful info -- Windell and Cordell should please definitely get in contact. We (here meaning Yorke, Chris Stubbs, Susana, Rob Zee, Bob Abraham, and I, at various different times, and others I am probably forgetting) have certainly discussed CubeSats and other modular educational formats. (BTW, this thread should probably be in our nanosat forum rather than here -- that's of course not a problem.) CubeSats of the type described in the links you mention, i.e. http://www.nasa.gov/directorates/heo/home/CubeSats_initiative.html and http://www.nasa.gov/offices/education/centers/kennedy/technology/elana_feature.html 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.
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).
3) We haven't yet tested this calibration technique from the $300/flight helium balloons that we
already have, so we should almost certainly gain at least a couple of years of scientific experience
with that before we attempt a many-$k launch of a source that needs to be calibrated at sub-
percent levels, in order to be useful, into space.
Nevertheless we'll of course continue working on a calibration nanosat, of a slightly larger and more-precisely-launched variety than the CubeSat format, and very hopefully we'll see one in space before the end of this decade.
cheers, thanks, justin
On Fri, 14 Aug 2015 14:19:24 GMT, Karun Thanjavur wrote:
> Hi Justin et al > When I visited the Canada-France-Hawaii telescope (CFHT) facility on the Big Island of Hawaii > two weeks back, I gave a presentation about Project Altair, which was very well received by the astros > and engineers alike. There was quite a bit of interest expressed in having flights over their > observatory when Altair is ready for science observations. Their instrument complement includes two > wide field imagers (MegaCam, WIRCam), a high resolution echelle spectrograph (Espadons), and the > recently commissioned imaging Fourier Transform Spectrograph (Sitelle) > > One of the engineers there, Windell Jones, worked on a nanosat (cubesat) > design for his Master's thesis at UH Manoa, and was particularly > interested in the nanoAltair design being led by Cordell and his UT > group. I am attaching my email exchange with Windell following my > presentation in which he has provided many useful links as well as a > copy of his thesis. Windell is also willing to participate in our > telecon at some point to discuss ideas, and I hope we can schedule a > telecon at a more reasonable time for him (HST = EDT - 6h) > > Sorry to have missed yesterday's telecon during which I wanted to talk > about this. Looking forward to following this up at our next meeting. > Cheers karun > > Attachment: > http://projectaltair.org/HyperNews/get/AUX/2015/08/14/07.17-76976-indell_cubesat_thesis.pdf > http://projectaltair.org/HyperNews/get/AUX/2015/08/14/07.17-92982-WendellCubeSatInfo.pdf >