Astronomy

Is there a name for this type of orbit of a natural satellite?

Is there a name for this type of orbit of a natural satellite?


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Is there a name for the orbit of a natural satellite of a planet who's period is the same as the rotational period of the planet, but the orbital motion has the opposite sense than the planet's rotation?

If there isn't an existing term or name, how would it at least be described, technically?

How much does the tidal effect affect satellites in a retrograde orbit?


No. Such an orbit would be co-incidental and dynamically uninteresting.

For a planet of given mass and rotation period, there is a class of orbits, whose period is equal to the rotation period of the planet. If the orbit is prograde this gives an interesting effect: the satellite would remain in the same position in the sky (or if it had an elliptical orbit, it would return to the same position each day)

If the orbit is retrograde, the orbit would not have any particularly interesting features. While it is possible for tidal locking to produce a synchronous orbit, there is no mechanism to stabilise a retrograde orbit like this, and tidal effects will slowly disrupt it.


There is probably no specific term, as I don't think such orbits occur naturally anywhere, nor there is any sense to launch an artificial satellite into such an orbit.

But in general terms if an orbital period of a satellite is equal to the period of rotation of a body it orbits, such orbits are called synchronous (e.g. geosynchronous if the satellite orbits the Earth). And if the orbit is in the opposite sense w/respect to the rotation of a body, the orbit is called retrograde.

So I would say that "synchronous retrograde orbit" would pretty unambiguosly point to a type of orbit you're describing.


Satellite Orbit Types & Definitions

There are many different satellite orbits that can be used. The ones that receive the most attention are the geostationary orbit used as they are stationary above a particular point on the Earth.

The orbit that is chosen for a satellite depends upon its application. Those used for direct broadcast television, i.e. satellite television for example use a Geostationary orbit. Many communications satellites similarly use a geostationary orbit.

Other satellite systems such as those used for satellite phones may use Low Earth orbiting systems. Similarly satellite systems used for satellite navigation systems like Navstar or Global Positioning (GPS) system occupy a relatively low Earth orbit. There are also many other types of satellite from weather satellites to research satellites and many others. Each will have its own type of orbit depending upon its application.

Also the new Cubesats or cube satellites use relatively low orbits as well in view of te power levels they can transmit and the allowable path losses.

The actual satellite orbit that is chosen will depend on factors including its function, and the area it is to serve. In some instances the satellite orbit may be as low as 100 miles (160 km) for a Low Earth Orbit LEO, whereas others may be over 22 000 miles (36000 km) high as in the case of a GEostationary Orbit GEO. The satellite may even have an elliptical rather than a circular orbit.


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About Satellites & Rockets | There Types

Satellite is a semi-independent device which has a specific job. Rocket is a type of missile that helps to launch artificial satellites.

What is Satellite

Satellite is a computer-controlled device. Every satellite has a particular role like communication, power generation, thermal control, weather checking, etc.

Types of Satellite
  • Astronomical Satellite
  • Bio satellite
  • Communication satellite
  • Geosynchronous satellite
  • Geostationary satellite
  • Earth Observation satellite
  • Navigational satellite
  • Killer satellite
  • Crewed spacecraft
  • Miniaturized satellite
  • Recovery satellite
  • Tether satellite
  • weather satellite
  • Drone satellite
  • Ground satellite
  • Polar satellite

Astronomical Satellite: These satellites‘ job is to find the galaxy, the Planets which are far away from earth, to observe them, and to notify us.

Bio satellite: It is normal for scientific experiments like a living organism.

Communication satellite: For telecommunications people use these satellites. Their location is in the space station. This satellite is of four types: LEO ( Low Earth Orbit), MEO( Medium Earth Orbit), GEO( Geostationary Earth Orbit), HEO( Highly Elliptical Orbit).

Geosynchronous satellite: These satellites stay in the orbit of the earth. It takes 24 hours to complete the earth. It moves like an eight pattern. Syncom 2 is an example of this. Space Technology & Exploration

Geostationary satellite: Except geosynchronous satellite All the communication satellites(LEO, HEO, MEO) are Geostationary satellites. It takes 24 hours to complete the orbit of the earth. These satellites don’t move and are about 35,788 km far away from earth.

Earth Observation satellite: This is especially for the observation of earth. Basically non-military services like meteorology, map making, etc. Use this.

Navigational satellite: When people want to detect the location of some device or some other people, they use this satellite for that purpose. It uses radio signals to locate the accurate position of the receiver. There is a line between the satellite and the mobile receiver.

Killer satellite: Scientists use it to destroy the space assets affecting the earth, the other satellites, etc.

Facts About satellite Space Technology & Exploration

Crewed spacecraft: This is also one type of satellite. This is large. People can travel in space with this type of spaceplane. It is reusable. More satellites

Miniaturized satellite: These satellites have very low masses. For mini-satellites, it is 500-1000 kg, for micro-satellite the mass is under 100 kg, and the nanosatellites have 10 kg mass.

Recovery satellite: When some payloads travel from orbit to earth, it can crash. That’s why scientists use these satellites to recover. It recovers reconnaissance, space products.

Tether satellite: A thin cable connects these satellites with another satellite. The cable is known as the tether.

Weather satellite: People send these satellites to observe the Earth’s atmosphere and climate.

Drone satellite: A drone satellite refers to an unpiloted spacecraft. It’s another name is UAV. People use this for military purposes only.

Ground satellite: It is like a radio station. People use it for telecommunication. These types of satellites are normally on the earth’s surface.

Polar satellite: This type of satellite moves from one pole to another. The polar satellites give meteorological information to us.

What is Rockett

Rocket is like a missile, spacecraft, aircraft, or another vehicle. People use rockets for fireworks, launching artificial satellites. Firecracker is an example of a rocket.

Types Of Rocket

Solid-Fuel Rocket: The oldest rocket is a solid-fuel rocket. When the Chinese invented the gun powder, this type of rocket is of that time. Here people use various types of solid chemicals for making one type of mixture. Nitroglycerin is the main thing here. Here it is easy to store fuel comparing to liquid fuel. Space Technology & Exploration

Liquid-Fuel Rocket: The liquid-fuel rockets use liquid material. The first-ever satellite contained liquid material. The rockets can also be bipropellant which allows the fuel to burn after mixing.

Ion Rocket: Ion rocket takes the electrical energy from the solar cells. Here the xenon ions help to get charged.

Plasma Rocket: VASIMR( Variable Specific Impulsive Magnetoplasma Rocket) normally works after the process of generation of plasma. Space Technology & Exploration The negative ions of hydrogen atoms produce this. This type of rocket is newer in development.

If we made any mistake in the above Article, please suggest us and give your valuable Feedback in Comment Box Thanks author of Space Technology & Exploration


60 Other Starlink Satellites Reach Orbit to Blind Earth Scientists Some More

by Daniel Patrascu

For a while now, scientists who look at the sky for a living have been crying that the glow caused by orbiting satellites and other types of space junk interferes with Earth-based instruments used to search the depths of space.

If there was any need for proof to support that claim, just remember how in the summer of last year, a Canary Islands-based photographer came up with a very peculiar shot of the Neowise comet on account of the Starlink satellites.

And now comes a scientific paper to back the claim that satellites can have a real impact on astronomy efforts. Published back in March by M. Kocifaj from the Slovak Academy of Sciences, it is among the first to determine just how severe this impact is.

According to the researchers, night sky brightness levels are changed by the sunlight reflected by orbiting bodies. Since there&rsquos a lot of them out there, light gets scattered and comes in conflict with those looking up from Earth&mdashas you probably know, it takes pitch darkness to see the stars properly.

As measured by Kocifaj, zenith luminance (that would be the luminance of the sky directly overhead) over the past few years jumped to 10 percent over the night sky's brightness determined by natural sources of light. That might not seem like much, but it breaks the light pollution level established in 1979 by the International Astronomical Union and causes radio interference and information loss for instruments studying the stars.

The paper concludes that the &ldquoproliferation of space objects is a rapidly increasing source of artificial night sky brightness&rdquo and affects &ldquoboth space operations and ground-based optical and radio astronomy.&rdquo

Is there a way out of this? Of course not. We&rsquoll probably not stop sending stuff into orbit in the foreseeable future (if anything, the pace of this activity will likely accelerate), and we certainly won&rsquot begin clearing the skies of all the junk now orbiting aimlessly around our world.

SpaceX, for instance, will continue putting its internet satellites in orbit until 12,000 of them are out there, surrounding our world.


Interplanetary Spacecraft

The exploration of the solar system has been carried out largely by robot spacecraft sent to the other planets. To escape Earth, these craft must achieve escape speed, the speed needed to move away from Earth forever, which is about 11 kilometers per second (about 25,000 miles per hour). After escaping Earth, these craft coast to their targets, subject only to minor trajectory adjustments provided by small thruster rockets on board. In interplanetary flight, these spacecraft follow orbits around the Sun that are modified only when they pass near one of the planets.

As it comes close to its target, a spacecraft is deflected by the planet&rsquos gravitational force into a modified orbit, either gaining or losing energy in the process. Spacecraft controllers have actually been able to use a planet&rsquos gravity to redirect a flyby spacecraft to a second target. For example, Voyager 2 used a series of gravity-assisted encounters to yield successive flybys of Jupiter (1979), Saturn (1980), Uranus (1986), and Neptune (1989). The Galileo spacecraft, launched in 1989, flew past Venus once and Earth twice to gain the energy required to reach its ultimate goal of orbiting Jupiter.

If we wish to orbit a planet, we must slow the spacecraft with a rocket when the spacecraft is near its destination, allowing it to be captured into an elliptical orbit. Additional rocket thrust is required to bring a vehicle down from orbit for a landing on the surface. Finally, if a return trip to Earth is planned, the landed payload must include enough propulsive power to repeat the entire process in reverse.


In this article, we will learn about Types of Satellites. Satellite plays an important role in our day-to-day life. Initially, they were used as a secret device for espionage and other undercover military activities. With more and more commercialization, they got into digital communication areas impacting our daily lives.

Satellite provides a range of services in several areas: beaming of Television programs worldwide, remote Phone calls, community radio, weather reports, news reports, Ola/Uber taxi-hailing, Geo Mapping, Vehicle tracking and many more. There are many business models built tapping the potential offered by satellite services. In this article, let us understand the features of Satellite and its types.

Web development, programming languages, Software testing & others

What is a Satellite?

In the Solar system, there are Sun, Planets, moons (Natural satellites). Sun is one of the stars in billions of stars in the Milky Way Galaxy. Milky Way is one among the billions of Galaxies in the universe. Any object that orbits around another bigger object in space is called Satellite. This orbit may be circular or elliptical in the path. The bigger object holds all the small objects revolving around it and provides life, light, heat, and energy to them.

1. Natural Satellite

Planets like Earth, Jupiter, Uranus, Saturn, Neptune and Mars orbiting around Sun and they are called Natural Satellites. Sun holds the entire solar system it takes up the central key position and provides all the resources to the planets. Moons like Titan, Ganymede, Callisto, Rhea, Miranda and the Moon orbiting Planets are also part of this natural satellite category. There are around 240 such moons in the solar system orbiting Planets, Dwarf Planets, and other solar system bodies.

2. Artificial Satellite

These satellites are built and placed in space, orbiting Earth or other Planets with specific intentions. An international space station is one such habitable Satellite placed in space, and it was built by five participating space agencies such as NASA (USA), JAXA (Japan), ESA (Europe), Roscosmos (Russia) and CSA (Canada) between 1998-2011 and this space station was visited by 230 Astronauts from 18 countries. This space station provides an environment for conducting space research and testing new missions to the moon and mars.

Natural Satellites are known as moons, and Artificial satellite is called Satellite, and we will continue the rest of our article with Artificial Satellite only.

History of Satellites

Sputnik 1 was the first Satellite, and Russia launched it in 1957. Post this, 8900 Satellites from 40 countries were launched. Out of these, around 5000 still remain in space, and 1500 of them are active, and the rest of them have reached the end of life and remain in space as debris. India has launched around 100 Satellite so far.

These satellites are placed in Space at different altitudes, and they are facing different planets depending on the applications. 63% of current operational satellites are at a low orbit level (< 2000 Km), 6% are at medium orbit level (< 20000 km), 20% are at the geostationary orbit level (< 36000 km) and the rest 2% at elliptic level (> 36000 km).

Types of Satellites

Satellites can be classified based on their applications, Orbit in which they are placed. Orbits are categorized by their Altitude, Inclination with reference to the equatorial plane, Eccentricity, Synchronization parameters, Planet Centered, Pseudo orbit and others. Types of Satellites based on their application are

Application Details
Astronomical Deployed for observation of distant planets, star, galaxy, and objects in-universe. It is a space Telescope hanging in space to photograph objects in space.
Biosatellite Places animals or plants in the space to conduct research on the effects of space on these living objects.
Communication These satellites support telecommunication. Telecasting, Phone calls, Internet connectivity, Radio, and much remote connectivity are typical applications.
Earth Observation Deployed to study environment, monitor climatic changes and mapping the earth for non-military purposes.
Navigation Facilitates to trace the exact location of any objects on the Earth. This leads to the development of new applications, technology, and business cases.
Killer (Military) Deployed to attack enemy satellites and space objects during the war period.
Space Stations Designed for human beings to live and conduct research on objects on planets, stars, and galaxies.
Reconnaissance Deployed for spying, surveying and scouting enemy territory during the war period.
Crewed Spacecraft These satellite ferry astronauts to space and brings them back to earth. It has good grounding facilities and helps astronauts in accessing spaces stations.
Recovery Recovery satellites are mainly used to recover bio, reconnaissance and other satellites back to earth.
Solar Power Space-based satellites gather energy from the Sun and transmit it to earth for consumption.
Miniaturized Smaller sized and lower weight satellites are launched at an economical cost used for the limited purpose of scientific data gathering and radio relay.
Tether Tether satellites are connected to another satellite by the tether. It is used as a secondary payload to another main satellite mainly used in students and mini-projects.
Weather These satellites are used to measure and report the Earth’s weather, and the reports are used in a weather forecast.

Uses of Satellite

  • Military Satellites: Satellite per se is not military or commercial, and the purpose for which it is deployed decides its class. Military satellites are used to spy, survey and track the space objects of the enemy country. They scan the space for the presence of the enemy’s object and feed photos and other inputs to the host country.
  • Weather Forecasting: Image feeds of the Earth by Satellites help to monitor climate conditions on the Earth and predict any extreme weather conditions like Strom, Hurricane, Cyclone and excessive rain and manage disasters effectively.
  • Direct to Home (DTH) Telecasting & Radio: Without the use of any cable, live TV programs can be received from Satellite. Transponders receive a signal from the broadcaster in a fixed frequency and send it to all our homes at a different frequency. Radio also works in the same concept, and the programs can be received in any remote corner of the world.
  • Navigation: Satellite Track and traces the location of any objects on the earth, and this facility enables us to connect vehicles, Employees, and everything with their owners.
  • Telephone: Satellite enables wireless telephone connectivity with any person in any remote corner on the earth, and this works in any weather.

Conclusion

Satellite communication helped Industry to accelerate Business transformation. New mobile applications are built using Satellite technology, and it connects all the stakeholders with Business.

Recommended Articles

This is a guide to Types of Satellites. Here we discuss what Satellites is, their type, history, uses in detail for better understanding. You can also go through our other related articles to learn more –


As you know already, every object exerts a gravitational force on another object. The higher the mass of the object, the greater is its gravitational force. The gravitational force of the Sun keeps the planets in orbit. Similarly, the gravitational force of the earth keeps the moon and artificial satellites in orbit around the earth.

However, the gravitational force alone is not enough for an object to stay in orbit. There has to be an equal and opposite force acting on these satellites. Otherwise, they will fall on earth. This opposite force is the satellite’s momentum. It is the product of the satellite’s mass and the velocity with which it moves.

On the other hand, without gravity, these satellites will leave their orbit and travel in a straight line away from earth. So, at every point in time, the gravitational force of the earth acting on the satellite and the momentum of the satellite have to be balanced. Only then can the satellite stay in orbit.

Velocity of the Satellite and its distance from Earth

The formula for the gravitational force acting on the satellite is :

Most of the satellites in this altitude that lose functionality are made to reenter earth, where they usually burn up. Therefore, this part of the orbit is congested with space debris – around 8,500 objects larger than 10cm and a million objects bigger than 2mm.

Polar orbit

Satellites in the low earth orbit, which pass over the Earth from pole to pole are said to be in Polar orbit. Polar orbits are at an altitude of 200 km – 1000 km. Polar orbits are normally used for earth observation, weather and reconnaissance.

By the time a satellite in a polar orbit completes one orbit, the earth would have turned a little bit. So, the satellite will now be in an adjacent time zone when compared to its last orbit. A satellite in polar orbit completes one orbit in (mostly) 90 - 100 minutes. Hence, in one day, it will see most of the earth twice.

Sun synchronous orbit

Polar orbits that are synchronous to the Sun are called Sun synchronous orbits. These orbits are at an altitude of 200 km – 600km. In a Sun synchronous orbit, regardless of when and where the satellite crosses the Equator, the local solar time is always the same. That’s why it is called Sun synchronous.

For example, whenever and wherever the NASA’s Terra satellite crosses the Equator, the local time at that moment at that place is always 10:30 am. This is important for comparing images from different years to find changes in weather, etc.


NOAA-17

A Weather forecasting satellite operated by NOAA. The NOAA satellites have asynchronous orbits, 824 km above the Earth, orbiting every 101 minutes. Spinning around the globe to spot developing weather patterns that affect billions of people. Satellite was retired in 2013 It hosted the AMSU, AVHRR and High Resolution Infrared Radiation Sounder (HRIS) instruments.


Key Milestones in Space Technology:

Here is a look at some of the key milestones in space technology:

October 4, 1957: soviet Union launches Sputnik-1.

January 4, 1958: United Space launches explorer 1.

April,12,1961: Yuri Gagarin becomes the first human to enter space and

July 18, 1969: launch of Apollo 11. It puts the first space station, the Skylab.

May 14, 1973: the United States launches its first space station, the Skylab.

June 18, 1983: Sally ride becomes the first American woman in space.

February 19, 1986: Mir space station launches.

September 30, 2003: First privately-owned spaceship launches.

August 4, 2007: Phoenix lander lands on Mars.

Kinds of Artificial Satellites:

The scientist has sent many satellites that move around the Earth. These satellites help scientists to learn about weather and many more things on the Earth.

Sputnik:

On October 4, 1957, Russia sent the world’s first artificial satellites, sputnik-1 into space. The name comes from a Russian word for “traveling companion of the world.” It weighed just 83 kg. It carried a thermometer and two radio transmitters which sent information about the atmosphere to the Earth. Its two transmitters only functioned for 21 days. After 57 days in orbit, it was destroyed.

Explorer 1:

Explorer 1 was the first satellite b launched by the united states of America. It was sent into space on January 31, 1958. It weighed only 14kg. Explorer 1 sent information about the radiation environment in the Earth orbit.

Geostationary Satellites

Geostationary satellites move at a height of about 36,000 km above the Earth. At this height, they move around the Earth at the same speed as the Earth moves around its axis. This satellite seems to be stationary. They are used as communication satellites. Pakistan has launched its first geostationary satellite, PAKISTAN-1R on August 11, 2011.

Landsat satellites:

The land lies is a series of os satellite missions. Since 1972, land set satellites have collected information about Earth from space. Landsat satellites have taken photographs of Earth’s continents and surrounding coastal regions.

Communication satellites

Communication satellites have a great effect on our daily lives. The link remote areas on the Earth with telephone and television. Newspapers are typed and transmitted to putting machines via satellite in some countries.

Polar Satellite

The polar satellite was launched on February 24, 1996, by America. Polar satellite studies atmosphere of the Earth in polar orbit after every 18 hours. The polar satellite will help scientists to protect future satellites from atmospheric dangers.

Global Positioning System

Satellites have improved our knowledge about space and even about out Earth. Using satellites, you can find your position anywhere in the world accurate to 10m or less. Locating the position of objects with the help of a satellite is called the global positioning system or GPS. It is freely accessible by anyone with a GPS receiving.