Tundra orbit

A Tundra orbit (Russian: орбита «Тундра») is a special way for satellites to move around the Earth. It is a highly elliptical path that matches the Earth’s rotation, called a geosynchronous orbit. This orbit has a high tilt, called inclination, of about 63.4°, and it takes exactly one sidereal day to go all the way around the planet. Satellites in this orbit spend most of their time over one area, which is useful for sending messages to places far north or south.

Animation of two Tundra orbits with inclination of 63.4° and different eccentricities. The apparent loop is due to the use of an Earth fixed frame, co-rotating during diurnal motion; the Tundra orbits are simple ellipses in an Earth-centered inertial frame. 0.2 eccentricity · 0.3 eccentricity · Earth

The Tundra orbit was created by scientists in the former Soviet Union. It was made after another special orbit called the Molniya orbit, which was created in the 1960s to help areas near the poles. The Tundra orbit is similar but lets a satellite stay above one region for a long time. Both orbits helped solve communication problems because of the Soviet Union’s large size.

One special feature of a Tundra orbit is the path the satellite appears to take when viewed from the Earth. This path, called the ground track, makes a figure-eight shape, with a smaller loop over the northern or southern half of the planet. This is different from the Molniya orbit, which moves more quickly. These orbits show how clever engineering can help connect distant parts of our world.

Uses

Tundra and Molniya orbits help send signals to places far north or south on Earth. From a regular geostationary orbit, which stays above the equator, it’s hard to send strong signals to these areas. In very far north places, regular satellites can’t even be seen.

Tundra orbits let satellites spend more time over these faraway places, which makes communication easier. But it costs more because you need two satellites to keep the signal going all the time. Also, satellites in Tundra orbits don’t have to go through dangerous areas around Earth called the Van Allen belts.

Properties

A Tundra orbit is a special path around Earth used for satellites. It has an angle, called inclination, of 63.4° and a period of 1436 minutes. This orbit is very stretched out, with a distance from Earth’s center, called semi-major axis, of about 42,164 km.

The Tundra orbit is designed so that satellites spend most of their time over certain areas of Earth, especially near the poles. This makes them useful for communication in places far from the equator. By choosing the right angle and shape for the orbit, the satellite’s path stays the same over time without needing frequent adjustments.

oblateness · argument of perigee · frozen orbit · geostationary orbit

ω ˙ = 3 4 n J 2 ( R E a ) 2 4 − 5 sin 2 ⁡ i ( 1 − e 2 ) 2 , {\displaystyle {\dot {\omega }}={\frac {3}{4}}nJ_{2}\left({\frac {R_{E}}{a}}\right)^{2}{\frac {4-5\sin ^{2}i}{(1-e^{2})^{2}}},}

Spacecraft using Tundra orbits

The groundtrack of QZSS orbit, which has similar characteristics to a Tundra orbit, but a lower inclination

Russia uses satellites in Tundra orbits for its EKS (Edinaya Kosmicheskaya Sistema) or Kupol system. These satellites help detect and track missile launches to give early warnings.

From 2000 to 2016, Sirius Satellite Radio used three satellites in Tundra orbits. This helped improve radio service in northern areas. After merging with XM, the system changed to use different orbits instead. The Quasi-Zenith Satellite System in Japan uses a similar orbit to serve better positioning in Japan.

Uses

Properties

Spacecraft using Tundra orbits

Images