### LNB An LNB, or Low Noise Block downconverter, is an essential component of a satellite communication system. If you have a satellite dish at home, the LNB is typically the only part of the satellite dish that contains electronic components and is located at the front of the metal arm. The LNB serves two crucial functions: it acts as a low-noise amplifier, taking the extremely weak satellite signal and amplifying it, and it also serves as a block downconverter, converting the high-frequency satellite signals to lower frequencies. The satellite signals are very weak by the time they they reach the dish. The large, round, "dish" part of the antenna acts as a lens, focusing as much signal as possible onto the LNB. The LNB then amplifies that signal and sends it down the cable to the satellite receiver or modem. In the case of the NSI configuration, they used an LNB with an ultra-high gain step, which provided an additional amplification stage, allowing them to communicate with a satellite that might otherwise be difficult to reach.  ### Motion Compensation Motion compensation is a technique used to reduce the amount of data required to represent a video sequence by exploiting the temporal redundancy between adjacent frames. In a video, consecutive frames often contain similar content, with only small changes or movements occurring between them. Motion compensation takes advantage of this similarity by predicting the content of a current frame based on the information from one or more previous frames. Instead of encoding each frame independently, the encoder identifies the motion or displacement of objects between frames and encodes only the differences (known as residuals) along with the motion information. In this context, upgrading the video segment from 384 Kb/s to 512 Kb/s allowed for better motion compensation. The higher bitrate provides more data for the encoder to work with, enabling more accurate motion estimation and compensation. This results in faster tracking of moving objects and improved overall video quality, especially in scenes with significant movement. NASA Science Internet (NSI) was a wide-area network established by NASA in the late 1980s to support scientific research and collaboration, in other words, non-mission critical computer networking. Its purpose was to connect NASA centers, research facilities, and educational institutions, enabling them to share data, resources, and communicate more effectively. NSI played a significant role in the early development of the Internet, contributing to networking technologies and protocols. It supported a variety of services like email, file transfer, and remote login, and it connected to other major networks of that era, such as the ARPANET and NSFNET, furthering the growth of the Internet. The Mars analog experiments conducted by NASA in Antarctica were designed to simulate conditions on Mars, utilizing the extreme and isolated environments of Antarctica as a stand-in for the Martian landscape. These experiments focused on understanding how humans could survive, work, and conduct scientific research in such harsh conditions. Key aspects of these experiments included testing life support systems, space suits, habitat designs, and scientific equipment that might be used on Mars. They also studied human behavior and performance under prolonged isolation and extreme conditions, crucial for long-duration space missions. In this context, the occultation is caused by the sun's infrared radiation interfering with the IR communication system when the sun is low on the horizon. The sun emits a significant amount of infrared radiation, which can overwhelm the IR sensors designed to detect the specific infrared signal used for communication. As a result, when the sun is in a particular position relative to the IR transmitter and receiver, its infrared emission overpowers the communication signal. You can watch the ABC segment [here](https://www.youtube.com/watch?v=E03JpFVvX5s) In 1992, NASA developed an underwater Remotely Operated Vehicle (ROV) designed to explore undersea environments in Antarctica. This ROV was notable for being controlled via a Virtual Reality headset. This pioneering technology allowed operators to control the ROV as if they were navigating underwater themselves, offering an immersive experience and precise control. You can see a video of the ROV in action [here](https://youtu.be/E03JpFVvX5s?t=783). ### Demarc A **demarc**, short for demarcation point, is the physical point where the responsibility for a telecommunications network or circuit changes from one party to another. Tracking satellites in inclined orbits presents unique challenges due to their orbital characteristics. Unlike geostationary orbits, which are on the same plane as the Earth's equator, inclined orbits are tilted relative to the equatorial plane. This tilt causes the satellite to appear to move in a figure-eight pattern as seen from the Earth's surface. As a result, antennas on the ground must constantly adjust their alignment to track the satellite's movement across the sky, which is more complex and challenging than tracking satellites in a stable, geostationary orbit. This constant adjustment is what makes maintaining a lock on a satellite in an inclined orbit more difficult. ### Ross Sea Ice Shelf The Ross Sea Ice Shelf, is the largest ice shelf in Antarctica, covering an area of approximately the size of France. The shelf can be anywhere from 300 to 6,000 feet thick. McMurdo’s station sits on the shelf’s western edge.  A multiplexer (MUX) is an electronic device that combines multiple input signals into a single output signal. In this case the MUX takes the separate voice and data streams and interleaves them, allowing them to be transmitted together over the same communication link. ### T1 Microwave Link A T1 microwave link is a type of digital transmission system commonly used in telecommunications. Microwave links are limited by the line of sight between antennas. This range is typically up to about 50 miles, but can vary based on factors like antenna height, frequency band, and environmental conditions. In this case, McMurdo station is about 22 miles from Black Island - well within the range of T1 link.  *Distance between McMurdo station and Black Island* INTELSAT, which stands for the International Telecommunications Satellite Organization, was founded in 1964 as an intergovernmental consortium. Initially, it had 11 member countries, but its membership grew over time. The primary goal of INTELSAT was to create a global satellite communications system that would facilitate international telecommunications and media broadcasting. In 1965, INTELSAT launched its first satellite, called Early Bird (Intelsat I), which provided the first two-way connection between Europe and North America. IntelSat played a crucial role in enabling live broadcasts of major world events, such as the Olympics and the Apollo 11 moon landing, to a global audience. This helped to connect people around the world and foster a sense of global community. Before the widespread adoption of fiber-optic cables and the internet, satellites like those operated by INTELSAT served as a vital backbone for international phone calls and television transmission. They provided a reliable means of communication across vast distances, even in areas where terrestrial infrastructure was lacking. In 2001, INTELSAT underwent a significant change as it was privatized, becoming a private company. The IntelSat 177 East that Mark León references in the paper is likely [Intelsat VA F-11](https://en.wikipedia.org/wiki/Intelsat_VA_F-11) (then named Intelsat 511), which operated at a Longitude of 177.0° East from 1992 to 1995. It’s important to understand a few key concepts when it comes to the orbits that satellites can assume: - **Inclined Orbit**: An inclined orbit is an orbit that is tilted with respect to the Earth's equator. The angle between the orbit plane and the equatorial plane is called the inclination. Satellites in inclined orbits do not maintain a constant position relative to the Earth's surface. They move in a sinusoidal pattern, oscillating between the northern and southern hemispheres. The inclination of the orbit determines how far north and south the satellite will travel. - **Geosynchronous Orbit**: A geosynchronous orbit is an orbit where the satellite's orbital period matches the Earth's rotational period. This means that the satellite completes one orbit around the Earth in the same time it takes the Earth to complete one rotation on its axis. Satellites in geosynchronous orbits have an altitude of approximately 35,786 kilometers above the Earth's surface. However, geosynchronous orbits can be inclined, meaning that the satellite may not maintain a constant position over a specific point on the Earth's equator. - **Geostationary Orbit**: A geostationary orbit is a special type of geosynchronous orbit that has an inclination of nearly zero degrees. Satellites in geostationary orbits remain at a fixed position relative to the Earth's surface, appearing stationary to ground observers. These orbits are located directly above the Earth's equator and have the same altitude as geosynchronous orbits (approximately 35,786 kilometers). Geostationary orbits are particularly useful for communications, television broadcasting, and weather monitoring, as the satellites can continuously cover a specific region of the Earth.