Huygens the Planetary Probe under VLBI Magnifier Leonid Gurvits Joint Institute for VLBI in Europe (JIVE) Dwingeloo, The Netherlands.

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

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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

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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