Round-trip latency is the time it takes a signal to travel from Earth to Mars and back.

As Mars and Earth orbit around the sun, their distance relative to each other is constantly changing. The minimum distance from Earth to Mars is 35,000,000 miles, and the maximum is 249,375,000 miles.

Since light travels at 670,000,000 miles per hour in a vaccuum, we can calculate the minimum and maximum round-trip latency:

  Minimum round-trip latency
  = (2 * 35,000,000 miles) / (670,000,000 miles per hour)
  = (0.167164 hours) * (60 hours per minute
  = 10.0299 minutes

  Maximum round-trip latency
  = (2 * 249,375,000 miles) / (670,000,000 miles per hour)
  = (0.744402 hours) * (60 hours per minute
  = 44.6642 minutes