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Rosetta flies by asteroid Steins - campaign overview

The Rosetta spacecraft flew by asteroid Steins at 18:58 UTC on 5 September 2008 at a distance of about 800 km. Details of the preparations for this event, and results from the asteroid fly by, were posted on this Science & Technology web site. All related articles are collated on this page.

Asteroid Steins is the first nominal scientific target for the Rosetta mission. The spacecraft will rendezvous with the asteroid in the course of its first incursion into the asteroid belt located between the orbits of Mars and Jupiter, while on its way to its primary scientific target, comet 67/P Churyumov-Gerasimenko.

End of Steins fly-by campaign

The asteroid Steins fly-by campaign ended on 4 October 2008 at which time the spacecraft was configured to low activity cruise. The two weeks following the fly-by were mostly devoted to downloading the science data recorded during the fly-by and making observations for the OSIRIS gravitational microlensing programme. Further details are given in:

Rosetta’s gravitational microlensing programme
Rosetta Status Report No. 105 - Gravitational Microlensing Observations
Rosetta Status Report No. 106 - Gravitational Microlensing Observations Completed

First images and results from the fly-by campaign

First images and results from the fly-by of asteroid Steins were presented at a press conference on Saturday 6 September starting at 12:00 CEST. For further details see:

First Rosetta/OSIRIS images of asteroid Steins

Science instruments ready for action

Nearly all of the orbiter’s instruments and the ROMAP magnetometer on the lander performed scientific measurements. In the four weeks leading up to the moment of closest approach the asteroid was imaged by the navigation cameras and by the OSIRIS camera as part of an optical navigation campaign aimed at fine-tuning the trajectory of the spacecraft. Most of the scientific observations were performed in the few hours around closest approach, although some measurements began a few days before.  See also:

Rosetta's scientific instruments prepare for close encounter with Steins

Optical navigation campaign - fine-tuning the spacecraft trajectory

For the month preceding closest approach to asteroid Steins the spacecraft navigation cameras and the OSIRIS camera performed an optical navigation campaign. The purpose of this was to refine the trajectory of the spacecraft relative to the asteroid and to adjust it, if necessary, to achieve the desired fly-by conditions: 800 km distance at closest approach on 5 September at 18:58 UTC and zero phase angle reached prior to closest approach. Further details can be read in the article:

Rosetta fine-tunes its approach to asteroid Steins

First results from the optical navigation campaign are available and are reported in:

Optical navigation campaign off to a good start
Perfect sight: Rosetta cameras track asteroid target

Details of the trajectory correction manoeuvres, including results from the measurements made to determine the position of the asteroid plus images from the navigation cameras and OSIRIS, can be found in:

Rosetta Status Report No. 102 - Start of Optical Navigation Campaign
Rosetta Status Report No. 103 - Closing in on Asteroid Steins
Rosetta Status Report No. 104 - Asteroid Steins Fly-by

Preparing for the encounter with asteroid Steins

Preparations for the fly by began on 1 July 2008 when the Rosetta spacecraft was taken out of near-Sun hibernation mode and configured to active cruise mode. The spacecraft and payload were then checked out prior to the start of the optical navigation campaign. You can read more about the preparatory activities in:

Preparations underway for Rosetta flyby of asteroid Steins
Rosetta Status Report No. 99 - Switch to Active Cruise Mode
Rosetta Status Report No. 100 - Active Payload Check-out 8
Rosetta Status Report No. 101 - Active Payload Checkout 8 Completed


Last Update: 15 July 2013

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