In order be in orbit around the Earth, a satellite needs to go very fast (greater than 12,000 miles per hour), and very high (greater than 125 miles up). Ordinary airplanes can’t go that high or fast, and even the fastest jet ever built, the SR‐71, could only go 2,200 mph at 15 miles up.n order be in orbit around the Earth, a satellite needs to go very fast (greater than 12,000 miles per hour), and very high (greater than 125 miles up). Ordinary airplanes can’t go that high or fast, and even the fastest jet ever built, the SR‐71, could only go 2,200 mph at 15 miles up.