Top 10 Strategies for Interplanetary Communication

Essential Insights

On Earth, we’ve grown accustomed to the convenience of smartphones, enabling us to call, message, or share photos and videos from nearly any location. Additionally, we increasingly rely on the ever-expanding wealth of online information, whether for scientific endeavors or navigating daily tasks like finding the fastest route to a destination.

However, the kind of immediate connectivity and high-speed data transfer we enjoy on Earth is still absent in space. The vast distances between celestial bodies introduce significant delays in electronic communications, and signals must traverse through space radiation, which diminishes their quality. Additionally, the constant movement of planets can cause their mass—or even the sun—to obstruct signals entirely.

Picture yourself as an astronaut tasked with setting up a colony on Mars, which is between 35 million and 140 million miles (56 to 226 million kilometers) away from Earth. These communication barriers would pose a serious challenge. With current technology, sending a message or making a call to mission control on Earth would involve a delay ranging from three to 21 minutes, making real-time conversation nearly impossible. Capturing and sharing a live video of something extraordinary on Mars is out of the question, as even transmitting a single photo is a slow and cumbersome process. NASA confirms that live video streaming from Mars is beyond our current capabilities. Even the latest upgrades allow robotic rovers on Mars to achieve data speeds of only about 256 kilobits per second—comparable to Earth's dial-up internet in the 1990s. Tasks like using cloud-based applications or exploring high-resolution maps of Mars would be impractical.

The challenges would grow exponentially if you traveled beyond Pluto and attempted to communicate with an Earth-like planet in another solar system. This is why scientists have spent decades brainstorming ways to bridge the immense cosmic distances and establish contact across the universe. Over the years, they’ve proposed numerous innovative solutions, and here are 10 of the most promising ideas.

10: Build a Network of Communication Satellites Across the Solar System

The concept of constructing a satellite network spanning nearly 3.7 billion miles (6 billion kilometers) across the solar system, from Mercury to Pluto, may seem overwhelming. However, in 1945, when British scientist and science fiction author Arthur C. Clarke proposed a global network of orbital satellites in a magazine article, it likely appeared equally far-fetched. Today, satellites are ubiquitous, enabling phone calls, texts, and emails from virtually any location on Earth. Interestingly, even before the first telecommunications satellites were launched, visionaries were already imagining an interplanetary version of Clarke's global network.

In 1959, space scientists George E. Mueller and John E. Taber presented a paper titled "An Interplanetary Communication System" at an electronics convention in San Francisco. Their work outlined methods for establishing long-distance digital transmissions in space using radio waves. Decades later, scientists Stevan Davidovich and Joel Whittington proposed an intricate system involving three satellites in polar orbit around the sun, complemented by additional satellites in geosynchronous or polar orbits around various planets.

This network of satellites would relay radio messages from manned spacecraft or robotic probes, transmitting them across the solar system until they reached Earth. However, no steps have been taken to build such a system, likely due to the astronomical costs associated with deploying multiple satellites around distant celestial bodies.

9: Transitioning from Radio Signals to Lasers

As highlighted earlier, data transmission speeds in space are currently far slower than the broadband internet we rely on Earth. The primary reason, without delving into complex mathematics, is that radio waves operate at frequencies that limit their data-handling capacity. This limitation is similar to the experience of using a wireless internet router, which is often slower and less reliable than a wired connection.

In contrast, laser light, with its shorter frequency and concentrated energy, can transmit significantly more data. Lasers also require less power than radio transmissions because they don’t disperse as widely. NASA’s Deep Space Optical Communications Project aims to replace radio transmitters and receivers with lasers, potentially increasing data transmission rates by 10 to 100 times. This advancement could make interplanetary internet speeds comparable to Earth’s broadband. However, implementing laser communication in space is challenging. NASA has conducted small-scale tests and is developing a system for lunar orbit trials. Eventually, lasers could enable high-definition live video streaming from Mars.

8: Integrating Probes and Rovers into an Interplanetary Communications Network

Earlier, we discussed the ambitious idea of creating a vast network of dedicated communication satellites spanning the solar system. While this would be a monumental effort, a more cost-effective and gradual approach might exist. Historically, spacecraft and satellites have communicated directly with Earth-based stations, using mission-specific software and equipment that is often discarded after use.

What if every spacecraft or object sent into space—such as space stations, orbital telescopes, probes orbiting Mars or other planets, and even robotic rovers exploring alien terrains—were equipped to communicate with each other, forming a vast interplanetary network? To draw a parallel, think of how your laptop, tablet, smartphone, gaming console, webcam, and home entertainment system can all connect to a wireless router and share data seamlessly.

Beyond relaying data, this interplanetary network could ideally integrate with Earth’s internet, allowing scientists to access orbital satellites or rovers and observe their findings in real-time, much like browsing NASA’s website today.

A 2005 article in IEEE Spectrum described how NASA’s future network might enable scientists to uncover groundbreaking details about Martian geology, the oceans beneath Jupiter’s icy moon Europa, or Venus’s turbulent atmosphere. It could also serve as the medium for astronauts to send emails back to Earth, bridging the vastness of space.

7: A Space-Compatible Internet

We’ve already discussed the concept of linking spacecraft and probes into a vast interplanetary network, allowing scientists to access them like websites on the internet. However, critics argue this approach may not be ideal because the internet’s fundamental design isn’t well-suited for space. The internet protocol used on Earth divides all transmitted data—whether text, voice, or streaming video—into small packets, which are reassembled at the destination. This method works well on Earth, where data travels quickly with minimal delays or losses, but space presents unique challenges.

In space, where distances are vast, celestial objects can obstruct signals, and electromagnetic radiation interferes with transmissions, delays and interruptions are unavoidable. To address this, scientists are developing a modified version of the internet using a new protocol called disruption-tolerant networking (DTN). Unlike Earth’s internet, DTN doesn’t assume a constant connection. Instead, it stores data packets until a connection is reestablished. NASA compares this to a basketball player holding the ball until a teammate is open, rather than making a risky pass. In 2008, NASA successfully tested DTN by transmitting images from a spacecraft 20 million miles (32.187 million kilometers) away.

6: Developing Satellites and Relay Stations for Other Planets

Communicating with a Mars base poses a significant challenge due to the planet’s constant motion. At times, the base may face away from Earth, and approximately every 780 Earth days, Mars and Earth align with the sun directly between them. This alignment, known as conjunction, can disrupt or block communication for weeks, a daunting scenario for astronauts or Martian colonists. Fortunately, European and British researchers may have a solution to this problem.

Satellites typically follow Keplerian orbits around planets, named after the 17th-century astronomer Johannes Kepler, who formulated the mathematical laws governing their motion. However, European and British researchers have proposed placing two communication satellites around Mars in non-Keplerian orbits. This means the satellites would not orbit Mars in a circular or elliptical path but would instead remain slightly offset, avoiding the planet’s center. To maintain this position, the satellites would need to counteract Mars’ gravitational pull using electric ion propulsion engines. These engines, powered by solar energy and fueled by small amounts of xenon gas, would allow the satellites to relay radio signals continuously, even during Mars-Earth conjunctions.

5: Deploy a Chain of Relay Stations

Interplanetary communication isn’t limited to our solar system. Since the discovery of the first exoplanet orbiting a sun-like star in 1995, scientists have identified numerous other exoplanets. In October 2012, they found an Earth-sized planet orbiting Alpha Centauri B, the closest star system to us, located approximately 2.35 trillion miles (3.78 trillion kilometers) away.

While this distance is immense, some scientists envision launching a massive starship—a self-sustaining, Earth-like vessel capable of supporting multiple generations of astronauts. This starship would journey across interstellar space to reach habitable planets and potentially establish contact with extraterrestrial civilizations.

Project Icarus, an initiative by space scientists and futurists to design a mission to the stars, tackled the challenge of maintaining communication with Earth as the spacecraft ventured deeper into space. One innovative solution proposed was for the ship to periodically release empty fuel canisters equipped with relay devices, creating a chain of signal stations. This chain would transmit messages back to Earth over shorter distances, reducing the need for high transmitter power or large antennas. As British engineer Pat Galea explained in 2012, this approach could also increase the data transmission rate.

4: Deploy a Network of Giant Antennas to Capture Signals

The team behind Project Icarus—a speculative endeavor to design a starship capable of reaching the nearest star system, approximately 2.35 trillion miles (3.78 trillion kilometers) away—dedicated significant effort to solving the communication challenge. While the previous section discussed a relay chain left by the starship, Earth-based monitoring would still face the difficulty of detecting faint signals amidst space’s electromagnetic noise. Earth’s atmosphere further complicates this by weakening incoming signals.

To address this, Project Icarus planners proposed building multiple solar system receiving stations (SSRS) with extensive antenna arrays spread across Earth. These antennas would work together to detect and amplify faint signals from the starship. Just as a baseball is more likely to be caught in a crowded stadium, a network of antennas increases the chances of capturing distant signals. Since Earth’s rotation limits each SSRS’s visibility to the starship, and weather can interfere, constructing multiple arrays in different locations would ensure near-continuous communication.

3: Harness the Sun as a Signal Amplifier

Another innovative concept from the Project Icarus team involves leveraging Einstein’s theory of relativity, which states that massive objects can bend and focus light passing near them, much like a magnifying glass. The researchers proposed positioning a communication spacecraft in interstellar space, approximately 51 billion miles (82 billion kilometers) from the sun, directly opposite the starship’s trajectory. This craft would use the sun’s gravitational field to amplify signals from the starship and relay them to Earth via a satellite network with laser links. While this idea is groundbreaking, it comes with significant challenges, such as maintaining precise alignment of the receiver spacecraft.

Engineer Pat Galea explained in 2012 that this method could drastically reduce the transmitter power needed on the starship or significantly increase the data transmission rate. However, the complexity of keeping the receiver spacecraft perfectly aligned poses a major hurdle. Despite its ingenuity, this approach requires overcoming substantial technical difficulties.

2: Ultra-Sensitive Receivers for Detecting Weak Space Signals

By the time signals from a distant spacecraft reach Earth, they are so degraded that they may carry less energy than a single photon. Photons, the smallest units of energy, are incredibly tiny; for comparison, a cell phone emits around 10^24 photons every second. Detecting such an incredibly faint signal amidst the noise of space is akin to finding a message in a bottle in the vast ocean. However, researchers have proposed a solution, supported by NASA’s Space Technology Program, to address this challenge.

Instead of transmitting a single signal, a spacecraft could send multiple copies of the same signal simultaneously. Upon reaching Earth, mission control would use a structured optical receiver, or Guha receiver (named after its inventor, Saikat Guha), to reassemble the fragmented and weakened signals into a coherent message. Think of it like shredding a thousand copies of a typed message, mixing the pieces, and then reconstructing the original text from the surviving fragments.

1: Faster-than-Light Communication Using Neutrinos

Despite the advanced technology we develop to decode faint signals from deep space, we face an even greater challenge: the vast distances within our solar system make real-time communication, like a Skype video call, impossible with current technology. For interstellar travel to planets beyond our solar system, communication becomes nearly unthinkable. For instance, a message to or from the Alpha Centauri star system, trillions of miles away, would take 4.2 years to travel one way. This has led visionaries to explore the idea of faster-than-light communication using subatomic particles.

While this might sound like a simple solution, it’s far from it. Such a method would seemingly violate Einstein’s theory of special relativity, which states that nothing can exceed the speed of light. However, in 2012, two mathematicians published a paper suggesting a way to reinterpret Einstein’s calculations to allow for faster-than-light speeds. Even if their theory holds, we still lack evidence that particles can travel faster than light.

In 2011, a widely-publicized experiment at CERN claimed to have detected neutrinos traveling slightly faster than light. However, the results were later attributed to a faulty fiber-optic cable connection, which produced an inaccurate reading. This setback has temporarily halted hopes of developing faster-than-light communication using neutrinos.