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Huygens the Planetary Probe
under VLBI Magnifier
Leonid GurvitsJoint Institute for VLBI in Europe (JIVE)Dwingeloo, The Netherlands
1629-1695 1625-1712
15.10.1997
Huygens entry, descent and landing: 14 Jan 2005
7 July 2005L.Gurvits, EC Press Conference, Dwingeloo, NL 4
Radio astronomy segment of the Huygens mission
Conceived as an Earth-based support to the Doppler Wind Experiment (DWE)
Included Direct carrier signal detection with DSN-supplied Radio Sci Receiver
(real time capability) at Green Bank and Parkes telescopes; Direct Doppler measurements (JPL-led experiment) at four NRAO
VLBA antennas; Very Long Baseline Interferometry (VLBI) tracking of the probe from
17 radio telescopes (including all six above);
Used (only!) the Channel A carrier signal at 2040 MHz only.
7 July 2005L.Gurvits, EC Press Conference, Dwingeloo, NL 5
Interferometry: a one-slide tutorial
Michelson & Young, 1890s: measurements of stars’ diametres
D
D
B B
Very Long Baseline Interferometry (VLBI):
the ultimate angular resolution in astrophysics
VLBI tracking of Huygens, 14 January 2005
09:30 UTC 16:00 UTC
Huygens VLBI tracking obtained:• 340 min of carrier signal• 26 TByte of data (equivalent of ~6,000 DVD movies)
Huygens signal paths
Cassini S/C
TCXO TCXO
TCXORUSO
TCXORUSO
Channel B
Channel A
“Channel C” – eavesdropping on Channel A carrier
Huygens Data
HuygensReceivers
HuygensProbe
7 July 2005L.Gurvits, EC Press Conference, Dwingeloo, NL 8
Huygens radial velocity measurements
Para
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ight
dyn
amic
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Wf
2
1
VLBI determination of the Huygens descent trajectory
“Doppler interferometry”: ~25 km
A priori accuracy: ~100 km
Full VLBI accuracy: ~ 1 km
VLBI tracking of the Huygens Probe
• Pushing the limits of high technology
• Demonstrates high-level synergy between radio astronomy and space exploration
• Paves the way for future experiments and applications – GPS-like accuracy anywhere in Solar System (Moon, inner and outer planets)
• Great promise of next generation radio telescopes and arrays (e.g. Square Kilometre Array, SKA)
7 July 2005L.Gurvits, EC Press Conference, Dwingeloo, NL 11
Huygens VLBI tracking team (abbreviated)
JIVE ESA-ESTEC NASA-JPL NRAOI.M.Avruch C.. van’t Klooster S.Asmar W.BriskenH.Bignall J.-P.Lebreton W.Folkner F.GhigoA.Brunthaler R.A.Preston G.LangstonR.M.Campbell J.RomneyM.A.Garrett L.I.Gurvits, R.OerlemansS.V.Pogrebenko
ASTRON ATNF U Tasmania NICT (CRL)A.R.Foley J.Lovell G.Cimo T.Kondo
C.Phillips. S.Elingsen
U Bonn J. Reynolds B.ReidM.Bird R.Sault.
T.Tzioumis
NAO China Helsinki U ISAST.An (ShAO) A.Mujunen R.DodsonX.Hong (ShAO) J.RitakariS.Huang (ShAO)D.Jiang (ShAO)X.Liu (UAO)
12 institutes and international 12 institutes and international organisations in 7 countriesorganisations in 7 countries