What we need now: Guidance system and other issues

Re: What we need now: Guidance system and other issues

Postby DaveHein » Sun Apr 10, 2011 6:42 pm

pyramids wrote:could you elaborate on horizontal sensor? That expression always makes me think of the gravity-detecting kind, which obviously does not work for a guidance system (gravitational and inertial forces are indistinguishable). One would need something else, like optical detection, which will be harder than the sun sensor we discussed.

A horizon sensor is based on infrared or optical detectors. The Earth's surface has an average temperature around 290K, so it's black-body radiation can be distinquished from the backgound radiation of space, which is much colder. Infrared horizon detectors use sensors that are sensitive to wavelengths around 10 to 15 microns since the peak black body radiation is in that range for a temperature of 290K. This type of sensor works whether the earth is illuminated by the Sun or not.

An optical sensor can be used when the visible portion of the earth is illuminated by the Sun. Pictures from high altitude balloons and from space show a fairly well defined boundary between the illuminated Earth and the black of space. However, there is a blue haze at the horizon, which obscures the boundary between space and the Earth. This can be reduced by filtering out the higher optical frequencies and using only the the red or near infrared frequencies.

Dave
DaveHein
 
Posts: 40
Joined: Wed Oct 28, 2009 2:30 am

Re: What we need now: Guidance system and other issues

Postby pyramids » Mon Apr 11, 2011 9:30 am

That should work (assuming again that we sufficiently well block out the rocket's exhaust flare from the sensors, but we've been assuming that all along).
Thanks, Dave!
pyramids
 
Posts: 25
Joined: Fri Mar 25, 2011 3:07 am

Previous

Return to Launch Vehicles

Who is online

Users browsing this forum: No registered users and 1 guest

cron