MIDES infrared sensor for altitude

[draqon]

infrared sensors can be used to find the thermal differences of planet Earth as seen from spacecraft and these differences in layers represent the altitude of spacecraft. How would the architecture of such an apparatus work?

Anyone got a more detailed engineering spec's on MIDES?

[draqon]

Other altitude proposed sensors...wouldn't magnetometer be useful?

[CheskiChips]

Maybe the sensor detects the quantity of a specific band of long-wave radiation, one unaltered by atmospheric conditions. The long wave radiation would follow the inverse square law, and therefore if there was a known amount that should exist altitude could be determined.
Although I don't exactly understand why this would be the preferred technique, one would think there to be many better methods.

A detection of the gravitational pull would be useful, it would have to take into account the change in gravitation along the sphere. If I recall, equatorial gravity is significantly less at long distances compared to polar gravity. However this would seem to be no less effective than accounting for the moderate changes in long-wave radiation expulsion over a daily cycle...or the different geological landforms.

[draqon]

Cheski the problem with gravity change sensor is that their are extremely expensive, heavy, and are prone to brake.

The idea is to have a sensor to determine altitude the cheapest way and a sensor that would weigh the least.

A low weight/power/cost infrared Earth sensor
Falbel, G.
Aerospace Conference, 2004. Proceedings. 2004 IEEE
Volume 4, Issue , 13-13 March 2004 Page(s):2716 - 2722 Vol.4
Digital Object Identifier 10.1109/AERO.2004.1368068
Summary:This paper describes and analyzes a <2.5 cu. in Earth sensor weighing <100 grams, providing ±1° single axis attitude readout accuracy for Earth orbit altitudes below 800 km. Above 800 km, orbit altitudes, the same volume sensor, can provide two axis attitude readout with the same or better accuracy. These low volumes, weights and costs are achieved by using the spacecraft computer to implement a proprietary algorithm that compensates for seasonal Earth horizon infrared radiance variations. This algorithm is described in this paper. Improvements in the ±1° accuracy can also be achieved by sensor fusion with a 40 gram two axis Sun sensor, which is described in a referenced paper.

The above paper shows that IRES sensors can be lightweight and with IR sensors on a low price range these days...assembling an altitude sensor out of it would be possible. Now all I need is an algorithm.

[draqon]

A detection of the gravitational pull would be useful, it would have to take into account the change in gravitation along the sphere. If I recall, equatorial gravity is significantly less at long distances compared to polar gravity.

yeah but you got to ackowledge the fact that the rocket will not fly straight up and the fact that its thrust will vary from instabilities in the combustion and therefore the accelerometer will not be that much of use for altitude perception. And the change in gravity from equatorial to poles are not that great, how would these changes be accounted for on a scale of just 50 miles range for example?

[draqon]

Basically I need orbital mechanics algorthms...anyone know were I can get them?