the exact altitude of the orbit. Calculated for a circular orbit of the orbital velocity is , but for a higher orbit the velocity is reduced to . The launch vehicle's delta-v needed to achieve low Earth orbit starts around . The pull of gravity in LEO is only slightly less than on the Earth's surface. This is because the distance to LEO from the Earth's surface is much less than the Earth's radius. However, an object in orbit is in a permanent free fall around Earth, because in orbit both, the gravitational force and the centrifugal force balance out each other. As a result, spacecraft in orbit continue to stay in orbit, and people inside or outside such craft continuously experience weightlessness. Objects in LEO encounter atmospheric drag from gases in the thermosphere (approximately 80–600 km above the surface) or exosphere (approximately and higher), depending on orbit height. Orbits of satellites that reach altitudes below decay fast due to atmospheric drag. Objects in LEO orbit Earth between the denser part of the atmosphere and below the inner Van Allen radiation belt. Equatorial low Earth orbits (ELEO) are a subset of LEO. These orbits, with low inclination to the Equator, allow rapid revisit times of low-latitude places on Earth and have the lowest delta-v requirement (i.e., fuel spent) of any orbit, provided they have the direct (not retrograde) orientation with respect to the Earth's rotation. Orbits with a very high inclination angle to the equator are usually called polar orbits or Sun-synchronous orbits. Higher orbits include medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), and further above, geostationary orbit (GEO). Orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation. In 2017, "very low Earth orbits" (VLEO) began to be seen in regulatory filings. These orbits, below about , require the use of novel technologies for orbit raising because they operate in orbits that would ordinarily decay too soon to be economically useful. Use A low Earth orbit requires the lowest amount of energy for satellite placement. It provides high bandwidth and low communication latency. Satellites and space stations in LEO are more accessible for crew and servicing. Since it requires less energy to place a satellite into a LEO, and a satellite there needs less powerful amplifiers for successful transmission, LEO is used for many communication applications,