Over the poles of the Sun Ulysses Operations

Newsflash (9-Feb-2009): Spacecraft-Earth range increasing again. S-band link margin expected unable to support playback from mid-March 2009. Newsflash (1-Jan-2009): Playback data available again intermittently since 31-Dec-2008 due to improving S-band link margin from decreasing spacecraft-Earth range. Click here for TM map. he Ulysses Mission is a joint undertaking between the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). Its goal is the exploration of the Sun's environment far out of the ecliptic plane. Ulysses is the only spacecraft to have visited this unique region over the northern and southern poles of the Sun. aunched on 6th October 1990, Ulysses has completed almost 18.5 years of continuous operations. The spacecraft has completed its third pass through the northern polar region of of the Sun and is on its outbound trajectory towards the orbit of Jupiter. nfortunately, the end of the mission is now imminent due to dwindling electrical power on-board the spacecraft, especially to power the internal heaters required to prevent the attitude control fuel from freezing. Once this fuel freezes, the spacecraft can longer be manoeuvred to keep it pointing at the Earth to maintain its data downlink. This situation is made worse by the failure of the last remaining working X-band travelling wave tube amplifier (TWTA) on 15th January 2008. Downlink is now via S-band which results in a weaker signal on-ground. Both the thermal and downlink conditions will only get worse with time as the spacecraft travels away from the Sun and Earth on this part of its orbit. Please see the news releases at the ESA and JPL websites. evertheless, the Ulysses flight control team still has a few more tricks up its collective sleeves to delay the day on which the fuel freezes, thereby postponing the final day of mission operations (on this side of perihelion anyway) - "We will squeeze the very last drops of science out of it". s of 31-May-2008, the downlink data rate was reduced to 512bps due to the deteriorating S-band link margin. During the week prior to this, the 1024bps S-band link margin has consistently hit 0db on the largest antennas (70m diameter) in Deep Space Network. As a result of this, data playback from the tape recorders has ceased, therefore the only data available from the spacecraft will be in real-time during a DSN 70m ground station pass. t present, mission operations is continuing beyond the originally announced end date of 1-Jul-2008. An announcement of the near-term operations plan was made by the Ulysses mission operations manager on 9-Jul-2008. ou are viewing the web page of the Ulysses Mission Operations Team which is based at the Jet Propulsion Laboratory in California. Its primary purpose is to provide the Ulysses science community with information about past, present and future operations of the spacecraft. ur site is divided into the following sections: Page last updated on 10 February 2009 (US Pacific Time) [ Home | Latest Info | Mission Details | Spacecraft Operations | Spacecraft Description ] [ Glossary | Feedback | Search this site | Photo Albums | Privacy Notice | About this site ] [ For Mobile Devices ]