International Conference and Exhibition on Satellite August 17-19, 2015 Houston, Texas, USA

Satellite Navigation is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location (longitude, latitude, and altitude) to high precision (within a few meters) using time signals transmitted along a line of sight by radio from satellites. The signals also allow the electronic receivers to calculate the current local time to high precision, which allows time synchronization. A Satellite Navigation system with global coverage may be termed a global navigation satellite system (GNSS). Satellite navigation systems that provide enhanced accuracy and integrity monitoring usable for civil navigation as well as Core Satellite navigation systems are currently GPS (United States), GLONASS (Russian Federation), Galileo (European Union) and Compass (China).

Satellites can be classified by their function since they are launched into space to do a specific job. The satellite must be designed specifically to fulfill its role. There are nine different types of satellites i.e.  Communications Satellite, Remote Sensing Satellite, Navigation Satellite, LEO, MEO, HEO, GPS, GEOs, Drone Satellite, Ground Satellite, Polar Satellite. Communications satellites are artificial satellites that relay receive signals from an earth station and then retransmit the signal to other earth stations. They commonly move in a geostationary orbit. A remote sensing instrument collects information about an object. 

Satellites are used for a large number of purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.

Satellite Communication Subsystems that are required on a spacecraft with details of Telemetry, Tracking and Command System. TTC&M refers to Telemetry Monitoring and Command subsystem. These subsystems are established on the earth. The telemetry and command subsystem provides us the information about the happenings going on with the satellites on the space.

Space Missions are currently spacecraft exploring Mercury, Venus, Mars, and Saturn, as well as a comet and an asteroid. The Voyager spacecraft are hurtling out of our solar system, while New Horizons speeds toward a 2015 encounter with Pluto. Closer to home, we have probes in lunar orbit, a handful of solar physics missions, space telescopes, and a small army of Earth-observing satellites. In Earth orbit, the International Space Station continues to soar around the planet with a continually staffed crew of astronauts and cosmonauts. 

Military satellite is an artificial satellite used for a military purpose. The most common missions are intelligence gathering, navigation and military communications. The first military satellites were photographic reconnaissance missions. Some attempts were made to develop satellite based weapons but this work was halted in 1967 following the ratification of international treaties banning the deployment of weapons of mass destruction in orbit. As of 2013, there are 950 satellites of all types in Earth orbit. It is not possible to identify the exact number of these that are military satellites partly due to secrecy and partly due to dual purpose missions such as GPS satellites that serve both civilian and military purposes.

Space debris is also known as orbital debris which is the collection of defunct objects in orbit around Earth. This includes spent rocket stages, old satellites and fragments from disintegration, erosion and collisions. Since orbits overlap with new spacecraft, debris may collide with operational spacecraft. There are more than 12000 track able items of space debris larger than 10 cm orbiting Earth, including derelict satellites, spent upper stages and fragments of old missions – all presenting a clear and present danger to current missions. Mitigation requirements also ban space systems from undergoing uncontrolled re-entry if the associated ground casualty expectancy exceeds 0.0001 per event. For such cases a controlled re-entry over unpopulated areas is mandated instead. 
 

Satellite Internet access is provided through communications satellites. Modern satellite Internet service is typically provided to users through geostationary satellites that can offer high data speeds, with newer satellites using Ka band to achieve downstream data speeds up to 50 Mbps. Satellite main challenge is Signal latency. The Latency is the delay between requesting data and the receipt of a response, or in the case of one-way communication, between the actual moment of a signal's broadcast and the time it is received at its destination. The amount of latency depends on the distance travelled and the speed of light. The mobile web refers to access to the world wide web, i.e. the use of browser-based Internet services, from a handheld mobile device, such as a smartphone or a feature phone, connected to a mobile network or other wireless network.

The Internet relies on the Transmission Control Protocol (TCP) to ensure packet delivery without errors. This allows TCP to achieve the fastest practical data transfer rate for the conditions present on the network. As a result, TCP moves out of slow-start mode quickly and builds to the highest practical speed. To prevent packets from being acknowledged twice, the spoofing equipment suppresses acknowledgments from the remote site. UDP - The UDP protocol cannot be accelerated because it is not a connection-based protocol. NetBIOS - This is a LAN technology that cannot be accelerated as it is not designed to function in a WAN environment.RDP (Citrix) and RCP (Exchange) can also be slow over a satellite connection.

The main applications of satellites are mainly categorized as, Weather forecast used to observations from which to analyses the current state of the atmosphere. Broadcasting services include radio and television delivered directly to the consumer and mobile broadcasting services. Earth observation satellites are used for observing the earth's surface, possible to see many features that are not obvious from the earth's surface, or even at the altitudes at which aircraft fly. The Global Positioning System (GPS) is the first core element of the satellite navigation system widely available to civilian users. During natural disasters and emergencies, when land-based communication services are down, mobile satellite equipment can be deployed to disaster areas to provide emergency communication services such as search and rescue operations. Remote sensing satellites might track animal migration, locate mineral deposits, watch agricultural crops for weather damage, or see how fast the forests are being cut down.

Satellite Challenges and Solutions are line of sight, it must clear an object by at least the radius of the dish being used. But sometimes it is failed due to uncomfortable situations in the climate. Reliable GPS positioning in city environment is a key issue: actually, signals are prone to multipath, and satellite geometry, despite its improvement with GNSS interoperability, remains poor in many streets. Non-Line-Of-Sight (NLOS) satellites cause important receiver-satellite range measuring errors, because the direct signal is blocked and only the reflected signal is tracked. One of the challenges of satellite communications is latency - delays caused by distance and switching.  While this hardly matters with web surfing or broadcasts, it does become significant where fast interaction is required between users. Transmission delay is a function of the packet's length and has nothing to do with the distance between the two nodes. This delay is proportional to the packet's length in bits.

Global online bandwidth forecasts and impact of high definition TV on satellite bandwidth demand.  Commercialization of space, new satellite technologies and capacity forecasts.  Future of geosynchronous satellites and low orbit satellites. "It is always difficult to see exactly where future satellite technology will go, but  imagine it will progress in a similar way to that of PC technology - basically satellites individually doing more dedicated tasks and then networking together to provide an overall greater capability. This will make individual nodes more focused and more cost effective. We may even see clusters of satellites in the future". Future large satellites in Earth orbit may be assembled in space, so one of the major challenges for future satellite technology we can see is using robotics for small satellites to construct larger ones. Robotics is also an area of development for inter-planetary satellites
 

In a more restricted sense, remote sensing usually refers to the technology of acquiring information about the earth's surface (land and ocean) and atmosphere using sensors onboard airborne (aircraft, balloons) or space borne (satellites, space shuttles) platforms. A remote sensing instrument collects information about an object or phenomenon within the instantaneous-field -of-view (IFOV) of the sensor system without being in direct physical contact with it. The sensor is located on a suborbital or satellite platform