Know Your Orbits: Where We Keep Our Most Important Stuff in Space

The place we name area formally begins about 60 miles (100 kilometers) above the floor, a delineation often known as the Kármán line. But that’s not a possible altitude for orbit, owing to atmospheric drag. To attain orbit, an object should ascend to altitudes starting at around 100 miles (160 km) above the surface. This is the bottom potential boundary of low Earth orbit, or LEO, which extends to a most altitude of about 1,200 miles (2,000 km), NASA says.

Satellites should preserve an orbital pace of round 4.9 miles per second (7.8 km per second) to stay in low Earth orbit. At this pace, it takes a satellite tv for pc roughly 90 minutes to finish a full circle of Earth. The Hubble Space Telescope, which orbits in LEO at an altitude of roughly 332 miles (543 km) and travels at speeds reaching 17,400 miles per hour (28,000 km/hr), completes nearly 15 revolutions of Earth each day.

LEO is a workhorse orbit inside which the overwhelming majority of our satellites are situated. As of April 30, 2022, some 4,700 operational satellites are in LEO, according to the UCS Satellite Database (the true quantity is now a lot increased, given the speedy tempo at which SpaceX is launching its Starlink satellites). Low Earth orbit is helpful as a result of it’s so shut, permitting, for instance, low-cost launches to area, Earth-observing satellites to take high-resolution photos of the floor, low-power amplifiers for information transmission, and fast and quick access to area stations (enjoyable truth: no human has traveled past LEO for the reason that Apollo period). What’s extra, the aircraft of low Earth orbits might be tilted, offering many obtainable orbital paths for satellites.

That mentioned, the pace poses an issue for communication and navigation satellites, because it’s difficult for floor stations to trace objects whipping round in LEO. Satellite constellations are an efficient however pricey work-around, as a number of satellites work collectively to create a digital web across the planet. Starlink is an effective instance—a megaconstellation currently consisting of 3,182 operating satellites that present web protection around the globe. The Iridium satellite constellation additionally works from LEO, offering voice and information protection to satellite tv for pc telephones and different receivers throughout the globe.

Another draw back of LEO is that it’s more and more house to quite a lot of space junk, stuff like defunct satellites, spent higher phases, launch adapters, slag particles, copper wires, and even flecks of paint. Frighteningly, massive swaths of LEO may ultimately change into inaccessible if nothing is finished to curb the quantity of particles in LEO.