As seen in the photos below from https://terra.nasa.gov/about Terra is reddish, so the answer to
Why is Terra reddish?
is exactly what you have suspected; because it is wrapped in a thermal protection film that is reddish in color.
However, the answer to a more interesting question:
Why am I surprised that Terra appears reddish?
would have several ...
The category of "observation satellites" is broad, because there are many types of observation (different wavelengths that reveal different characteristics of the observed planet). Because you're referring to 'high-resolution images' I'm going to assume you want visible-light photography.
Yes, this is available for many bodies, although most planets have ...