SEDSAT-2 Payload Design Notes 20070420
From SEDSWiki
SEDSAT2: Payload Study –
Contents |
Thermal imaging
This idea has been recommended by the Payload team as a possible secondary payload for SEDSAT-2. Reason: Getting infrared images could possibly be done using the primary imaging device without alteration (if supported). Pro: Modest requirements. Con: Focus will not be optimal.
Purpose: To observe the earth through the Infra red spectrum.
Approach
Using a conventional cmos chip it is possible to observe the IR spectrum, an average cmos chip can image wavelengths up to 1100nm using certain filters. The same cmos chip could do both the IR and visible imagine, thus saving mass and weight. This would only be a viable option if we are capable of discerning the difference in temperature between the oceans and continents at the very least.
This would only really be considered as a secondary payload concept due to the limitations of its use. However, this would make observations of the earth very interesting.
Conclusion
This is a feasible concept, it would not be a complex module to implement, it would also be suitable due to the fact that it would not use any more mass or weigth than an any other cmos chip.
Sun/star imaging
This idea has NOT been recommended by the Payload team. Reason: Using the same amount of resources to acquire Earth images will yield better results. Too demanding to be a secondary payload.
Purpose: To observe the suns chronosphere.
Approach
Using a secondary camera fitted with a H-alpha filter, observe the sun.
To be able to image the sun’s interesting features such as sun-spots, filaments and prominences would require a camera fitted with a H-alpha filter.
A filter with a bandwidth of 2Å may only show prominences but a 1Å filter (which is considered narowband) will show prominences and surface detail. Some filters now go down to as low as .1Å. The narrower the bandwidth, the more contrast disk detail tends to have but the higher the price.
H-alpha has a certain width due to physical processes going on on the sun. The "wings" of H-alpha are the edges of this profile off the centerline wavelength. 6562.8 Angstroms is the so-called "centerline" (the middle of the spectral line's profile) and is where the filter should be tuned to generally.
The "wings" of solar H-alpha emission are nearly one angstrom wide, although usually we observe something like 0.7 Angstroms off the peak when we are looking in "the wings". Much farther off the peak than 1 Angstrom and we often see nothing but white-light detail (unless it is material from a really energetic solar flare, which can be a couple of Angstroms off).
All the H-alpha filters found sofar have been for general telescopes, so filter size may be an issue, I havent found any that are directly suitable for cmos cameras, most are attached to telecopes first.
Sources Novac, SWAC.
Another aspect of solar imagine would be the need for altering the attitude an determination necessary for taking an image.
Also would the orbit matter greatly in the feasability of the such a payload?
Conclusion
The ability to observe the suns chromosphere could be possible, but the draw backs could be the mass of a secondary camera/H-alpha filter and added complexity.
Also the fact that the possible orbit may hinder the effectiveness of solar observations.
