CCT_ORB- EoL Herschel -20131204_v2

Transcription

Centres de Compétence Technique
CCT ORB – Orbital Mechanics
CCT SCA – AOCS
http://cct.cnes.fr
Seminar :
The End-of-Life of Herschel & Planck
satellites
Wednesday, December 4th 2013 (09:45 – 12:00)
CNES Toulouse Space Center
18 Avenue Edouard Belin, 31401 Toulouse, cedex
***
End-of-life operations of Herschel and Planck satellites were performed during 2013. The choice of disposal
orbits for these space objects was of special interest due to their orbital position at L2 Lagrange point. Firstly,
this seminar will present the different options analyzed for the disposal orbit of Herschel and explain why an
external heliocentric orbit was chosen. Then, both satellites’ end-of-life operations will be presented, dealing
with both Flight Dynamics and AOCS aspects.
The seminar will be hold at CNES Toulouse Space Center in Leonard de Vinci room. The registration is
mandatory, especially to enter CNES site (see link below). Please ask for Clémence LE FEVRE at the
reception desk.
Les opérations de fin de vie des satellites Herschel et Planck ont eu lieu dans le courant de l’année 2013. Le
choix de l’orbite de fin de vie de ces satellites a fait l'objet d’études particulières en raison de leur
positionnement au point de Lagrange L2. Une première partie présentera les différentes options envisagées
pour Herschel et les éléments ayant conduit au choix d’une orbite héliocentrique externe. Une seconde
partie présentera un retour d’expérience des opérations de fin de vie d’Herschel et Planck en ce qui
concerne la dynamique du vol et le sous-sytème SCAO.
Le séminaire se tiendra au CNES Toulouse, en salle Leonard de Vinci. L’inscription au séminaire est
obligatoire pour accéder au site du CNES (voir lien ci-dessous). Demandez Clémence LE FEVRE à
l’accueil.
For registration / pour inscription :
https://cct.cnes.fr/content/s%C3%A9minaire-les-orbites-de-fin-de-vie-herschel-et-planck
Registration :
For more information : [email protected]; [email protected]
CCT SCA – AOCS
http://cct.cnes.fr
Programme :
Title
Author
Affiliation
M. Landgraf
ESA/ESOC
Manoeuvring for Demise - A
Report on the Actual Disposal
Operations for Herschel and
Planck
R. Mackenzie
ESA/ESOC
Herschel AOCS after the end
of the scientific mission
Y. Roche
Thales Alenia Space
How to Put Away a Space
Telescope
09 :45-10 :00
Welcome & Coffee
10 :00-10 :40 How to Put Away a Space Telescope
M. Landgraf – ESOC
All good things come to an end - even the biggest space telescope ever: "Herschel".
The helium coolant that is required for scientific observations ran out in spring 2013 and it
was clear that something would have to be done about Herschel, because its large
amplitude libration orbit around L2 is connected to the Earth surface via the unstable
manifold. Therefore there was the risk that an uncontrolled switch-off-and-forget could lead
to interference with the protected orbital regions in GEO, MEO, and LEO or to a reentry.
For Planck the situation was slightly less severe due to the spatial separation of the
unstable manifold from the near-Earth environment. Both missions enjoyed residual fuel
on board both due to prudent planning, efficient station-keeping, the very precise injection
by the Ariane 5 launcher, and the lucky scheduling of their launch in the launch window.
The options for their disposal that were discussed seriously were: (1) external heliocentric
orbit, (2) impact to the lunar surface, (3) controlled reentry, and (4) a demonstration
mission to the Earth-Moon L2. After a painstaking discussion option (1) selected.
Registration :
CCT SCA – AOCS
http://cct.cnes.fr
10:40-11:20 Manoeuvring for Demise - A Report on the Actual Disposal
Operations for Herschel and Planck
R. Mackenzie - ESOC
After the selection of the disposal mode into an external heliocentric orbit for
Herschel and Planck, it was the task of the ESOC flight dynamics team to translate the
strategy into actual manoeuvres and to fix the time-line of operations. One challenge was
the determination of the date of the end of science in combination with the limited
departure window in spring 2013. The initiation of the drift could take place before the end
of science, but the Jacobi-raise manoeuvre that was supposed to use up all possible
propellant had to be safely after that date, because then no further scientific operations
could be performed. In the end both manoeuvres were performed successfully and
Herschel and Planck are now on a drift orbit that will bring them back to the Earth's vicinity,
but unlikely to less than 2 million km - at least not for the next 300 years.
11:20-12:00 Herschel AOCS after the end of the scientific mission
Y. Roche – Thales Alenia Space
After a launch on May 14th 2009, Herschel fulfilled its mission for 1446 days. On 29th April
2013, the superfluid helium used to passively cool down the cryostat and the instruments
ran out, causing the end of mission.
The final disposal delta-v maneuver was then performed on 13th May and eventually, the
contact with the satellite was intentionally lost on 17th June.
The presentation focuses on the specificities of the AOCS during the post-helium phase:
sensor and actuator status, specific tests, and impact of the helium loss causing a
changed environment for the attitude control.
Registration :
CCT SCA – AOCS
http://cct.cnes.fr
Access :
Centre spatial de Toulouse
18 avenue Edouard Belin
31 401 TOULOUSE CEDEX 9
FRANCE
Tél : 33(0)5 61 27 31 31
Registration :

CCT_ORB- EoL Herschel -20131204_v2

Transcription

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