ESA title
Enabling & Support


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ESA / Enabling & Support / Operations

NAPEOS (NAvigation Package for Earth Orbiting Satellites) is portable navigation software for Earth Orbiting satellite missions. 

It provides orbit determination and prediction, manoeuvre optimization and global parameter estimation capabilities and is able to process a wide variety of observation data, including: angles, range, range-rate, altimetry, satellite-to-satellite links and GNSS data.

The most widely used techniques at the Navigation Support Office are: GNSS (GPS, GLONASS and GIOVE), SLR and DORIS.

In the late 1990s, due to the growing number of projects involving Earth satellite missions (ERS-1/2, Envisat, etc.) all with generically similar requirements for orbit determination, prediction and control, ESOC identified the need for a software package to cover future missions.

NAPEOS was meant to be a general-purpose software package to provide support for all phases of an Earth Orbiting Mission in terms of mission preparation and operational support for orbit determination, prediction and control.

It has since become ESOC’s state-of-the art tool for high-precision orbit determination and has proven to be capable of centimetre-accuracy orbit restitution.

The Navigation Support Office is currently using NAPEOS for all operational systems. In the field of GNSS processing, NAPEOS is very well suited for:

  • GNSS precise global estimation (station coordinates, earth rotation parameters, orbits and clocks of satellites and stations, ambiguities, troposphere)
  • Combining GPS, GLONASS and GIOVE (in the future, GALILEO) data even for very large station networks (> 150 stations) very efficiently
  • Station precise point positioning, both static and kinematic, using as input precise information about satellite clocks and orbits
  • Low Earth orbit satellite precise orbit estimation

Its performances has been validated against other software packages and is maintained through the use of several test cases, each one of them covering different features of the software (e.g., orbit estimation or propagation of LEO or MEO satellites).

All of these test cases provide excellent results with respect to the state-of-art for this kind of processing.  NAPEOS is operated through an X-Windows graphical user interface and has been ported to architectures such as UNIX-like operating systems (SUSE/Ubuntu Linux, Mac OS, Cygwin on Windows).


NAPEOS implements all knowledge on orbit determination and parameter estimation acquired up to now at ESOC in Earth Orbiting Missions (ERS-1, ERS-2, ENVISAT, GPS, GLONASS, GIOVE, Lageos, GOCE, etc.).

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