Hubble's orbit is 350 miles above Earth and set at a 28.5-degree angle relative to the equator. Just bringing the scope to the ISS's 52-degree orientation would require a tremendous amount of rocket power, but getting it to the station's orbit 150 miles below would kill it. The descent would generate enough atmospheric drag to damage the scope's solar panels. Worse, the space around the ISS is full of gases, liquids and other debris jettisoned from the station that could gum up Hubble's optics.