To help everyone better understand the science behind the rocketry, we provide the answers to your most pressing rocket science questions.
Have a question? Email it to firstname.lastname@example.org. We’ll answer as many as we can and will feature it here on this site.
A Geocentric Orbit is an orbit of any object revolving around the Earth. The orbits most commonly used are Low Earth (LEO), Medium Earth (MEO), and Geostationary (GSO).
In the late 17th century, Isaac Newton introduced his theory on gravitational law. This theory states that every particle of matter in the universe attracts every other particle of matter in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Scientists were able to build on Newton’s law, along with subsequent evolutions in physics theory by scientists such as Konstantin Tsiolkovsky and Walter Hohmann, and develop the basis for orbital maneuvers that give launch vehicles the ability to insert artificial structures in orbit around the Earth for long-standing periods of time.
In 1945, Arthur C. Clarke became the first scientist to publish an article proposing that geostationary orbits could be used to create global telecommunication relays.
A LEO, or Low Earth Orbit, is the lowest altitude an object must achieve in order to orbit the Earth. Because objects in LEO are so much closer to Earth, they experience a drag caused by atmospheric resistance. LEO is generally defined as an orbit between an altitude of 160 km and 2000 km. Most artificial satellites and all manned space stations, to date, have been placed in LEO.
A MEO, or Medium Earth Orbit, revolves a satellite around the Earth in between Low Earth Orbit and Geosynchronous Orbit. Any satellite that orbits the earth between an altitude of 2,000 km and just under 35,786 km is in MEO. The GPS satellite constellation is in a MEO.
A GSO, or Geostationary Orbit, is a circular prograde orbit which revolves a satellite on the Earth’s equatorial plane. A GSO is a subset Geosynchronous orbit (GEO) and has a zero degree inclination. GEO is approximately 35,786 km above the Earth's equator and follows the direction of the Earth's rotation. All Geostationary Orbits are Geosynchronous, but not all Geosynchronous Orbits are Geostationary.
ILS Proton Facts
The Intelsat 23 mission was the 4th Geostationary Orbit insertion mission for ILS Proton. Most ILS missions place satellites into a transfer orbit, and then the satellites are remotely maneuvered into their geo-location by the satellite manufacturer. However, when a satellite is less than 3,200 kg, as is the case with Intelsat 23, the Proton has the performance capacity to inject the spacecraft directly into a near circular geosynchronous orbit – this is known as a geostationary orbit insertion mission. This type of mission gives Customers an advantage, in that they are able to use less spacecraft fuel for maneuvering the satellite into its final orbit.