ILEWG Venus Express During MESSENGER Venus Fly-By

Håkan Svedhem, Venus Express ESA VEXAG#4 5 November 2007 1 ILEWG MESSENGER Venus Flyby Coordination observations at Venus

1. Observation of the same region before and after the flyby 2. Complementary viewing geometry of cloud 3. Atmospheric dynamics 4. Airglow measurements 5. Plasma investigations

MESSENGER Key instruments: Laser Altimeter, MDIS(camera), UVVS, VIRS (spectrometers) MAG, EPPS Venus Express Key Instruments: Virtis, VMC, MAG, ASPERA VEXAG#4 5 November 2007 2 ILEWG Venus Orbit vs MESSENGER CA

• Orbit number: 410 • Pericenter time: 5-June-2007_06:43:32 (UTC) • Position [lat, long]: [82.2 (N), 183.1 (E)] (degrees) • ALTITUDE: 252.1 km

• Orbit number: 411 • Pericenter time: 6-June-2007_06:43:57 (UTC) • Position [lat, long]: [82.2 (N), 184.6 (E)] (degrees) • ALTITUDE: 252.1 km

VEXAG#4 5 November 2007 3 ILEWG Geometry of the MESSENGER flyby

Closest approach: 5 June 2007 23:06:51 UTC – 337 km Altitude –

Lat = 12.2S - Lon = 165.0E

VEXAG#4 5 November 2007 4 ILEWG Orb 410 descending

SCIENCE RATE: east part of track night, central GREEN: Messenger cloud track part of track day, 15-16h earlier. COLD obs. (at altitude 65km, or ~100m/s) RED: +- 4min (LIDAR track) HIGH priority ILEWG Orb 411 descending

SCIENCE RATE: east part of track night, central GREEN: Messenger cloud track part of track night, 1 day later. COLD obs. (at altitude 65km, or ~100m/s) RED: +- 4min (LIDAR track) HIGH priority ILEWG Orb 412 ascending

SCIENCE RATE: west part of track day, central GREEN: Messenger cloud track part of track night, 1 day later. HOT obs. (at altitude 65km, or ~100m/s) RED: +- 4min (LIDAR track) HIGH priority (but hot) ILEWG

VEXAG#4 5 November 2007 8 ILEWG Venus Express observations 5-6 June Surface reference

VEXAG#4 5 November 2007 9 ILEWG Data volume downloaded during fly-by period

VEX_VI Instrument: VEX_ASP VEX_MAG VEX_PFS VEX_SPI R VEX_VMC Total

KByte Mbit

DOY 155 Jun 4 11660 2774 0 13691 0 53412 652

DOY 156 Jun 5 13904 2776 0 17230 269491 44996 2787

DOY 157 Jun 6 13336 2775 0 16075 241826 44479 2548

DOY 158 Jun 7 5427 2774 0 35 0 34652 343

VEXAG#4 5 November 2007 10 ILEWG

• ASPERA 5 June

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• ASPERA 6 June

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• VMC UV image ascending branch orbit 410 • Limited performance due to lack of good flat field frames

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• VMC UV image descending branch orbit 410

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• VIRTIS • Oribit 410 • 2007-06- 05T09:45:11.6 • 2.3 micron • 39000 km

VEXAG#4 5 November 2007 17 ILEWG

• VIRTIS • Oribit 410 • 2.3 micron

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• VIRTIS • Oribit 410 • 2.3 micron

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VEXAG#4 5 November 2007 21 ILEWG

• VIRTIS

• Airglow at 1.27 micron

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VEXAG#4 5 November 2007 25 ILEWG More

• As it happened the MESSENGER fly-by occurred just at Venus maximum elongation from the sun. At this time a combined ground based and space based observation campaign was running. Several teams observed Venus during this period • A session dedicated to the observations during the Fly-by will be held at the fall AGU meeting • A workshop addressing the ground based observations will be held in ESTEC 17-19 December.

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