Tuesday, September 20, 2011

UARS Is Definitely Descending From Orbit

UARS is predicted to make its reentry sometime this weekend possibly late Friday evening or early Saturday morning depending on one's time zone. I have been studying the changes in the satellite's orbital elements and did a polynomial fit to the UARS's perigee as a function of the UTC day of the year. The plot below is the "altitude" as defined by the difference between UARS's perigee and the Earth's equatorial radius. The eccentricity is also decreasing which means that the orbit is becoming more circular.

It is predicted that UARS will reenter off the east coast of Africa but the exact location and time are somewhat uncertain. UARS probably has its greatest interaction with the Earth's upper atmosphere near the Equator because of the equatorial bulge and greater height of the atmosphere there.

If you have ever seen a meteoric bolide they are truly impressive. UARS should be heated to luminescence on reentry. As it passes overhead at night UARS is not alway visible since it is usually in the Earth's shadow but one may be able to capture an IR image if it is heated enough by atmospheric friction.

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