Comments on: Polar Orbit vs Sun Synchronous Orbit

By: Rakesh Singh

Rakesh Singh — Thu, 09 Mar 2023 01:39:00 +0000

There are some Global positioning systems like India’s Navic which uses Geosynchronus satellites. US GPS however uses Medium Earth Orbit satellites.

By: Sanjay Prasad

Sanjay Prasad — Wed, 23 Nov 2022 01:27:03 +0000

This article in its original form must have been published in April 2019 or earlier. And thereafter, in the comments published above certain facts stated in the article have been claimed to be wrong by many readers. The article itself has again been updated on 30 May 2022. So, it leads to more confusion when one reads this article along with the comments published here. The original article should not have been modified. Instead, the author should have published clarificatory notes from time to time, if felt necessary, for a better understanding of the facts.

By: Walid

Walid — Sat, 04 Apr 2020 19:02:05 +0000

Dear sir/madam,

It is stated that “When a satellite has a sun-synchronous orbit, it means that it has a constant sun illumination through inclination and altitude.” This is wrong, a satellite in sun synchronous orbit is not always illuminated by the sun. The correct definition is that the orbital plane of a satellite in sun-synchronous orbit always has the same orientation with respect to the sun. Please let me know if it is changed.

Kind regards,
Walid El Bouhali
Aerospace engineering student

By: Binoy Barman Roy

Binoy Barman Roy — Sat, 26 Oct 2019 17:11:20 +0000

IN order to keep the satellite in orbit once it has the required speed no engine on board is needed to keep it in motion( Newton’s 1st Law of motion) neglecting air drag or orbit correction.

By: Maurizio

Maurizio — Thu, 29 Aug 2019 14:34:23 +0000

I agree with Steve VanWambeck on GPS constallation.
With regard to Christakis Fellas, the article meant that acceleration due to earth’s gravity, which basically equals centripetal acceleration of the circular trajectory, provides an orbit with a period equivalent to earth’s rotation.

By: Dr Christakis Fellas

Dr Christakis Fellas — Sat, 29 Jun 2019 09:10:17 +0000

It is stated in the article that: In the case of geostationary satellites, the Earth’s force of gravity is exactly enough to provide acceleration required for circular motion.
This statement is wrong. What happens in the case of a geostationary satellite is that the force of gravity at that height is exactly matched by the force of the satellite momentum, which is provided to the satellite by the launcher engines and the engine on board the satellite (called the Apogee Engine). There is no acceleration as such but a constant angular speed of 360 degrees per 24 hours.

By: Hema

Hema — Sat, 18 May 2019 16:09:48 +0000

Very simple and informative…Thank you so much

By: Steve VanWambeck

Steve VanWambeck — Thu, 11 Apr 2019 22:16:15 +0000

The statement “Weather, communication and global positioning satellites are often in a geostationary orbit” is incorrect. GPS is based on Medium Earth Orbits of six orbital planes.