“Deep space” is a term used by NASA and the aerospace industry as any distance further than the moon. Meanwhile, the European Space Agency (ESA) considers the same term to mean distances greater than 2 million kilometers, which is over five times greater than the distance to the moon.
What Space Exploration Has Achieved
Not only have astronauts visited the moon, but NASA has also sent equipment in space to explore other planets, particularly Mars. In addition, sophisticated spacecraft regularly send photos and data back to Earth for scientists to analyze. One of NASA’s deepest space missions launched in 1977 to explore the outer Milkyway galaxy, which continues today. Another mission was launched in 1997 to study Saturn, which is also still in progress over 1. 3 billion km from Earth.
In 2007, the Voyager mission documented 1,600 km/hr winds on Neptune. Later exploration led to the discovery of Planet HD 106906b and how it has a different gravitational relationship with its parent star than the Sun and Earth. The Rosetta space probe discovered organic carbon compounds on a comet, which may contribute to further evidence on how life started on Earth.
Limits of Space Technology
Despite NASA’s amazing ability to launch thousands of spacecraft over the years to build sophisticated deep space networks, data collection is much slower in space than on Earth. Nevertheless, the space agency expects data transmission rates to increase by nearly tenfold with new advancements over time. For example, the data currently sent to Earth from Rosetta is received at a speed of 104.86 kb/sec while Voyager 2 data is received at 160 bytes/sec.
Another limitation involving even the most advanced spacecraft is solar power. Today’s spacecraft are fueled by a mix of solar power and radioisotope thermoelectric generators (RTGs). Solar energy weakens once a spaceship gets into deep space, so RTGs take over as the primary power source. Even though RTGs can generate long-term power, they aren’t yet capable of generating volumes of power at the low mass needed for spacecraft to be optimized. Telecommunications equipment on spacecraft tends to make up just a few kilograms. The Voyager uses up to only 360 watts for its telecommunications technology.
Spacecraft used to explore deep space must be designed for long-term reliability without maintenance since missions usually last ten years or more. Unfortunately, technical problems have occurred on missions, such as in 1991 with the failure of Galileo’s High Gain Antenna (HGA) to set up properly. All attempts to fix it failed as the mission was forced to rely on just its Low Gain Antenna (LGA) at a much lower bandwidth.
Another example of a technical breakdown in space was in 2011 with the Russian space agency Roscosmos. Its Phobos-Grunt mission was unable to sustain itself in in space and crashed back down to Earth in early 2012.
RF Challenges
The power of RF communication from deep space to NASA ground stations is very low. That’s why highly sensitive equipment is needed to ensure the signals are received properly. Voyager 2 is equipped with an S-Band transmitter to communicate with NASA’s 70m dish antennas. But the signal is so weak, an amplifier must be used to boost the signal. While accounting for Earth’s rotation, dishes must be positioned with precision to thousandths of a degree per second, pointed at the spacecraft.
Space communication takes place in a frequency range from 1GHz to 300 GHz concentrated in the lower bands: L-Band, S-Band, X-Band, and Ka-Band. While higher frequencies can deliver higher data rates, they face more atmospheric interference.
Conclusion
The advent of deep space networks continues to improve throughout the galaxy. Radio intensity decreases with distance, so scientists must deal with enormous challenges in successfully receiving data from space. Designing durable, low-maintenance spacecraft for long missions is essential, with anticipation of more resilient renewable energy in the future.