Complex sentence: 's Shuttle Radar Topography Mission STS-99 reveals part of the diameter ring of the crater; clustered around the crater's trough are numerous sinkholes, suggesting a prehistoric oceanic basin in the depression left by the impact.
Split into simpler sentences: 's Shuttle Radar Topography Mission STS-99 reveals part of the-diameter ring of the crater. The numerous sinkholes clustered around the trough of the crater suggest a prehistoric oceanic basin in the depression left by the impact.