Buzz
Mars' orbiting satellites could play a key role in transmitting data back to Earth via an interplanetary network.The Internet and advancements in electronic communication have made it possible to connect with people anywhere on Earth almost instantly. Now, scientists and space explorers are working on a method to communicate quickly beyond Earth. The next stage of the Internet will extend to distant parts of our solar system, paving the way for communication systems supporting manned missions to Mars and beyond.
To uncover more about other planets, we will need an upgraded communication system for future space missions. Currently, space communication is incredibly slow compared to Earth's network. Several factors contribute to this delay:
- Distance – On Earth, communication happens almost instantaneously since we are just a tiny fraction of a light second apart. However, as we venture further into space, there is a delay of several minutes or hours due to the vast distances light must travel to bridge the gap between transmitter and receiver.
- Line of sight blockage – Anything that obstructs the line between the signal transmitter and receiver can disrupt communication.
- Weight – Powerful antennas designed to improve communication with deep space probes are often too heavy to be sent on a mission, as the spacecraft must carry a light, efficient payload.
It’s quite possible that humans will reach Mars before the next century begins. How will we keep in touch with these faraway explorers? Scientists, engineers, and programmers are already working on creating an interplanetary Internet to link us to space probes and astronauts, enabling more data to be sent back to Earth. If you’ve ever dreamt of space travel, this edition of How Stuff Will Work will explain how the interplanetary Internet could make it possible for anyone to journey into space, just as the Internet lets us explore foreign lands from our desks. It will also delve into the technologies that will support such a vast communication system in space.
Connecting the Solar System
A set of six microsatellites could be placed in low Mars orbit to enhance data transmission from Mars missions.
Photo courtesy NASA / JPLLooking back at the 1997 Mars Pathfinder rover mission will highlight the need for an interplanetary Internet to enable deeper space communications. During the Pathfinder mission, data trickled back at a rate of just 300 bits per second. Your computer probably transfers data over 200 times faster than that! An Internet connection between Mars and Earth could provide speeds of 11,000 bits per second, which, while still slow compared to your computer, would be enough to transmit clearer images of Mars' surface. Mars Network researchers anticipate that speeds could eventually reach 1 Megabyte (8,288,608 bits) per second, allowing for virtual trips to Mars.
An interplanetary Internet would function much like the Earth-based Internet but on a grander scale and with certain improvements. Here are the three essential components of the proposed interplanetary Internet:
- NASA's Deep Space Network (DSN) is a crucial system.
- A new method has been developed for transferring data.
The DSN's extensive array of antennas is instrumental in transmitting and receiving data over the interplanetary Internet.
Image courtesy of NASA / DSNThe Deep Space Network (DSN) is a worldwide network of antennas managed by NASA, responsible for tracking and controlling the navigation of spacecraft exploring the solar system. This system is designed to maintain constant radio communication with spacecraft, though some recent missions, like the Mars Climate Orbiter and Mars Polar Lander in 1999, experienced communication failures. The DSN consists of three global facilities located in California, Australia, and Spain. Each of these sites has various antennas, including one 111-foot (34-meter) diameter high-efficiency antenna, one 111-foot beam waveguide antenna (with three in California), one 85-foot (26-meter) antenna, one 230-foot (70-meter) antenna, and one 36-foot (11-meter) antenna.
In an interplanetary Internet, the DSN serves as Earth’s main connection point to the network. According to a paper from MITRE Corp., the company sponsoring the Interplanetary Internet Study, it is suggested that the DSN antennas could be aimed at Mars to maintain a connection between Earth and Mars for up to 12 hours a day. Mars' orbiting satellites would ensure a continuous link between the two planets. A rover, probe, or human colony on Mars could function as a gateway to the interplanetary Internet.
Under the Mars Network plan, the DSN will interact with a network of six microsatellites and a large Marsat satellite in low Mars orbit. These six microsats will serve as relay stations for spacecraft on or near the Martian surface, facilitating more data transfer from Mars missions. The Marsat satellite will gather information from the microsats and transmit it to Earth. It will also maintain continuous communication between Earth and distant spacecraft, allowing for high-bandwidth data and video transmission from Mars. NASA is considering launching a microsatellite as early as 2003, with the six-satellite constellation planned to be operational around Mars by 2009. The Marsat is expected to enter a slightly higher orbit in 2007. These dates remain tentative.
A team of developers is working on creating an Internet file transfer protocol to send messages and resolve issues related to delays and interruptions. This protocol will serve as the foundation of the whole system, much like how the Internet Protocol (IP) and Transmission Control Protocol (TCP) function on Earth. Dr. Vinton Cerf, who co-developed IP and TCP in the 1970s, helped create these two protocols that serve as the communication system for the Earth-based Internet. They divide messages into smaller data packets and direct them to their intended destinations.
Cerf is part of the scientific team developing a new protocol that will ensure reliable file transfers over long distances between planets and spacecraft. This new space protocol must maintain the Internet's functionality, even if some data packets are lost during transmission. It also needs to filter out interference encountered while traveling vast distances. One proposed solution for this is the Parcel Transfer Protocol (PTP), which would temporarily store data at each planet's gateway and relay it as needed. Each gateway would process the information, forward it, and send a response back down the transmission path.
Astronomical Challenges
An interplanetary Internet system will allow data to travel much faster between Earth and distant spacecraft. However, before embarking on a virtual journey to Mars through cyberspace, engineers must first overcome several challenges. These include the following:
- The delay caused by the speed of light.
- The risk of hacker intrusions.
On Earth, the farthest distance between two connected computers is only a few thousand miles. Since light travels at 186,000 miles per second, it takes only a fraction of a second to send data from one computer to another. However, the distance between Earth and Mars can range from 38 million miles (56 million km) to 248 million miles (400 million km). At these immense distances, it can take several minutes or even hours for a radio signal to travel. Therefore, an interplanetary Internet won't have the same real-time responsiveness as the Internet we use on Earth. Instead, a store-and-forward system will send data in chunks, helping to prevent information loss due to delays.
The Mars Network's satellites will be situated tens or hundreds of millions of miles away from Earth, which makes it difficult to perform repairs when things go wrong. To ensure reliability, the components of these satellites must be far more dependable than those currently orbiting Earth.
Hackers represent a major risk to the interplanetary Internet. Unauthorized access or tampering with navigation or communication systems could have catastrophic consequences for space missions, including fatalities on manned spacecraft. Developers are taking every possible step to create a system that can control access effectively. The protocol chosen must be impervious to hackers, something that has yet to be achieved on Earth. The Secure Sockets Layer (SSL) protocol, used to protect financial transactions, could serve as a potential model for safeguarding the interplanetary Internet.
The interplanetary Internet may connect us to Mars within the next decade, and eventually to other planets. Space travel will no longer require physical journeys—rather, virtual space exploration will bring the wonders of space to your desktop. With improvements to data transfer rates, you and I could soon embark on a virtual space trip to Mars’ mountains, Saturn’s rings, or Jupiter’s Great Red Spot.
