How Mars Rovers Communicate with Earth

Ethan Wong

July 15, 2022

The most frustrating and infuriating thing that is universally agreed upon by all humans is poor connection. Whether a destructive interference due to geological or atmospheric problems, to lousy network issues, terrible reception is the one nuisance that can corrupt a society overnight. However, fast connections and service are merely tiny advancements and can be easily fixed, in comparison to a communications system using radio waves that travels more than 125 million miles across 2 planets. Since 1993, the Mars Exploration Program has worked to send rovers over the years to explore Mars for past life, geological samples, and exploration; yet the ability for NASA to obtain communication with the Rovers itself is a huge feat throughout space engineering and exploration.

Although communication between the ISS, the Moon, and Earth have all been established, nothing compares to that of Mars. The amount of delay that is normally received on a call between the Moon and Earth is a mere 1 second, while the ISS and the Moon is less than a second. The time of signals and communication between Mars and Earth using radio waves can vary from 5 to 20 minutes; whatever happens on Mars, NASA will only know about it at least 5 minutes after it has occurred on the red planet. The main way that Mars rovers and Earth maintain connection is through a unique type of electromagnetic waves known as X-band, which are radio waves that have a much higher frequency than traditional radio waves used by Frequency Modulation Systems (FM systems). These radio waves are transmitted back to Earth in two different ways: directly back to Earth using a Deep Space Network antenna (DSN), or by orbiters that continuously orbit Mars.

NASA has two satellite crafts: Mars Odyssey, and Reconnaissance Orbitors, that orbit Mars to receive and transmit radio waves from rovers back to Earth; the satellites are in place because the rovers will lose connection with NASA. Since Mars is constantly spinning, the rover will eventually become hidden in a blind spot, where it will disappear from the range of connection and view from Earth, regardless of the DSN position/location. This is where the orbiters come in handy. Mars Rovers use Ultra-High Frequency (UHF) antennas to transmit radio waves directly toward Deep Space Network Antennas back on Earth. The UHF antennas equipped on the rovers can also be utilized to send signals to the orbiters as well. The rovers also have a High-Gain Antenna (HGA) which is used for the Rover to directly speak to Earth; the antenna is steerable which enables the rover to save energy. The Mars Odyssey Orbiter detects radio waves from Rovers during and after landing and immediately sends them to Earth, whereas the Mars Reconnaissance Orbiter acts as a “backup” and gathers the radio waves, then transmits them hours later. This is because Odyssey is moving quickly around the planet, causing it to only detect the radio waves sent by rovers for a short amount of time. The orbiters are also closer to the rover, allowing it to conserve energy, while still being able to communicate back to Earth.

Despite the previous use of this communication for the Voyager missions, which have gone into a much further space territory, this exciting way of using electromagnetic waves creates a whole new opportunity for discovery and advancements in communication and technology in space. However, there are still plenty of challenges to tackle before the first human sets out toward Mars. Calls from space centers and Mars need to be engineered to experience less time delay, while solar conjunctions are still short inconveniences. Yet, this amazing technological advancements will continue to help safely land and contact astronauts and capsules and furthering space exploration.