Same Time of Day

All of the tests have been conducted at essentially the same time of day-with the planned intercept occurring two to four hours before local sunset at Kwajalein where the intercept took place. This means that the sun is in a similar location for each test, and illuminates the mock warhead and other objects from behind the kill vehicle. As a result, the illumination of the objects is very similar in each test and the kill vehicle is approaching the objects with the sun to its back.

The time of day at which the test occurs is relevant in part because the infrared signature of an object in space depends strongly on the whether the object is in sunlight or the earth's shadow (at night), and for how long it is in sunlight.