During a meeting with the Mars Exploration Program Analysis Group, an internal NASA working crew dedicated to supporting missions to Mars included a pitch from Elon Musk’s SpaceX to deploy Starlink satellites around the red planet to create “Marslink.” Having a thick layer of satellites around Mars would certainly make transmission easier, as it would make the comms target larger than the planet itself and would likely speed up intra-Mars comms when that becomes necessary. But it probably won’t demonstrably speed up communication between Earth and Mars, at least not to the extent Elon is pitching, because Mars is really fucking far away.
The Marslink pitch includes “multiple SpaceX satellites placed in Mars orbit to provide full visibility and interoperability for ground and orbital assets,” and the ability to “exceed” NASA’s requirement for 4 mbps transfer. For reference, your average internet connection in the U.S. is humming around 250 mpbs, and you need around 100 mbps for reliable video streaming. Last week Elon Musk said in one of his 100-plus daily tweets that “This is just a very basic first step. Earth and Mars will ultimately need greater than petabit/sec connectivity.” Petabit/second speeds are currently only theoretically possible with fiberoptic cables, and we’re definitely not linking Earth to Mars with fiber internet.
Mars does not move in the same orbit around the sun, or at the same speed as Earth. At its closest, Mars is a mere 34 million miles away, about half the distance from the Earth to the Sun. When Mars is opposite Earth in its orbit, with the Sun between them, that distance increases to over 250 million miles. If you could communicate at the speed of light, as many laser-based satellite transmissions can, the speed at which you can load anything is still dependent on the speed of light. That 250 million miles takes 22 minutes and 22 seconds for light (or information) to traverse. Petabit/second speeds between Mars and Earth are impossible until we develop faster-than-light travel, which is, you know, not possible based on our current understanding of physics.
Elon Musk, again on Twitter, suggested that Starlink could create a “data bridge” to hop data from one satellite to another along a relay system. One follower even suggested a “web of satellites around the sun” to keep people in space and on other planets connected to the Earth internet. “A long chain of modified future generation Starlink satellites between 1 and 1.5 AU would do it,” claims Musk. If you don’t know, an AU (Astronomical Unit) is 93 million miles, or the average distance between the Earth and the Sun.
Here’s the problem. Satellite hopping does not reduce the speed at which you can communicate with a distant planet. Space is still space, lightspeed is still lightspeed, and the distance doesn’t get shorter because you put a few satellites between here and there. It’s possible that jumping from satellite to satellite could increase the size of the data transfer, but it will not reduce latency time between Mars and Earth in any way. In fact, hopping from satellite to satellite will actually increase processing time and make the whole thing slower.
Is Elon Musk going to be the one to crack faster-than-light travel and quantum entanglement? I’m going to go out on a limb here and say I have my doubts. SpaceX is scheduled to deploy five unmanned rockets to Mars in 2026, and Elon says people will be going to Mars by 2028. Again, I have my doubts.
