Browse Definitions:
Definition

apogee

 

When a satellite follows a non-circular orbit around the earth, the satellite's path is an ellipse with the center of the earth at one focus.Such a satellite has variable altitude and variable orbital speed. The point of highest altitude is called apogee.The term also applies to the maximum distance in kilometers or miles between the satellite and the center of the earth.(Apogee can be measured between the satellite and the earth's surface, although this is a less precise specification because the earth is not a perfect sphere.The difference is approximately 4,000 miles or 6,400 kilometers.)

At apogee, a satellite travels more slowly than at any other point in its orbit. When viewed from the earth's surface, a satellite at or near apogee takes along time to traverse the sky. In communications, apogee is the best time to access a satellite. Although its distance means that the signal path is long, the fact that the satellite is slowly moving means that it is accessible for a comparatively longtime. In addition, if a directional antenna is used at a ground-based station, it is relatively easy to track the satellite because the position of the antenna (azimuth and elevation) need not be adjusted very often or rapidly.

One of the principal advantages of a geostationary satellite is the fact that it follows a circular orbit, so the orbital speed is constant. In addition, the satellite's synchronization with the earth's orbit means that the antenna of an earth-based station can be pointed at a fixed spot in the sky, and no further adjustment of antenna orientation is needed.

Compare perigee .

This was last updated in June 2010

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

SearchSecurity

  • black hat

    Black hat refers to a hacker who breaks into a computer system or network with malicious intent.

  • copyright

    Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative ...

  • keylogger (keystroke logger or system monitor)

    A keylogger, sometimes called a keystroke logger or system monitor, is a type of surveillance technology used to monitor and ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

SearchStorage

  • open source storage

    Open source storage is data storage software developed in a public, collaborative manner that permits the free use, distribution ...

  • CompactFlash card (CF card)

    A CompactFlash card (CF card) is a memory card format developed by SanDisk in 1994 that uses flash memory technology to store ...

  • email archiving

    Email archiving (also spelled e-mail archiving) is a systematic approach to saving and protecting the data contained in email ...

SearchSolidStateStorage

  • RRAM or ReRAM (resistive RAM)

    RRAM or ReRAM (resistive random access memory) is a form of nonvolatile storage that operates by changing the resistance of a ...

  • JEDEC

    JEDEC is a global industry group that develops open standards for microelectronics.

  • M.2 SSD

    An M.2 SSD is a solid-state drive (SSD) that conforms to a computer industry specification written for internally mounted storage...

SearchCloudStorage

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close