What is an Highly Elliptical Orbit?

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Sep 16, 2022

Highly elliptical orbit (HEO) is a satellite orbit that has an altitude of about 1,000 to 35,756 km above the earth’s surface. Satellites in HEO are used for communications, satellite radio, remote sensing, and astronomical observations.

A satellite in an HEO orbit takes around 12-24 hours to complete one orbit around the earth. A major feature of an HEO is its apogee and perigee points. HEOs have a low perigee (the point of orbit closest to the Earth) with an altitude of under 1,000 km and a high apogee (the point farthest from the earth) with an altitude of over 35,756 km. 

As the satellite approaches perigee, orbital velocity is at its maximum, and as the satellite approaches apogee, the orbital velocity decreases and is at its minimum. This indicates that the satellite spends more time in the Apogee, where it moves very slowly and can be in the view over its operational area most of the time. The Satellite will have maximum coverage of the Earth’s surface when it is at the apogee (the point farthest from the earth), and have minimum coverage when it is at perigee(the point of orbit closest to the Earth).

HEOs can be used to provide coverage over any point on the globe. As a result of this ability to provide coverage over high latitudes over a specific region, countries such as Russia which need coverage over polar and near-polar areas make significant use of highly elliptical orbits. With two satellites in any orbit, HEOs can provide continuous coverage. Their only main disadvantage is that the satellite's position from a point on the earth does not remain the same and hence requires multiple satellites perfectly timed in the same path for continuous coverage.

Parameters

HEO Attributes

The altitude of HEO From Earth

1,000 to 35,756 km

Orbital Velocity for a satellite in HEO

High Velocity Near Perigee, Low Velocity near Apogee

Orbits Completed in a Day for a Satellite

1-2 Orbits per day

Satellites Needed

2 for Global Coverage

Propagation Loss

Smaller on one side, Higher on the other side of the earth

Network Complexity

Complex

Broadband Capability

Mediocre


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Name Date
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Sentinel 6 21 Nov, 2020
Cheops 18 Dec, 2019
EDRS 06 Aug, 2019
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Sentinel 5 13 Oct, 2017

isro

Name Date
INSAT-3DS 17 Feb, 2024
XPoSat 01 Jan, 2024
Aditya-L1 02 Sep, 2023
DS-SAR 30 Jul, 2023
Chandrayaan-3 14 Jul, 2023
NVS-01 29 May, 2023
TeLEOS-2 22 Apr, 2023
OneWeb India-2 26 Mar, 2023
EOS-07 10 Feb, 2023
EOS-06 26 Nov, 2022

jaxa

Name Date
XRISM 07 Sep, 2023
SLIM 07 Sep, 2023
ALOS-3 07 Mar, 2023
ISTD-3 07 Oct, 2022
HTV9 21 May, 2020
HTV8 25 Sep, 2019
HTV7 23 Sep, 2018
HTV6 09 Dec, 2016
HTV5 19 Aug, 2015
HTV4 04 Aug, 2013

nasa

Name Date
NEO Surveyor 01 Jun, 2028
Libera 01 Dec, 2027
Europa Clipper 10 Oct, 2024
SpaceX CRS-29 09 Nov, 2023
Psyche 13 Oct, 2023
DSOC 13 Oct, 2023
Psyche Asteroid 05 Oct, 2023
Expedition 70 27 Sep, 2023
SpaceX Crew-7 25 Aug, 2023
STARLING 18 Jul, 2023