Venus Express

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Venus Express

Venus Express in Venus orbit
Organization ESA
Major contractors EADS Astrium, Toulouse, France, leading a team of 25 subcontractors from 14 European countries.
Mission type Orbiter
Satellite of Venus
Launch date November 9, 2005
Launch vehicle Soyuz-Fregat
Mission duration Cruise Earth to Venus: 150 days; in-orbit around Venus: 1000 days
NSSDC ID 2005-045A
Webpage Venus Express (ESA)
Mass 1270 kg
Orbital elements
Semimajor axis 39468.195 km (intended)
Eccentricity 0.8403 (intended)
Inclination 89.99 deg (intended)
Orbital period 24 h (intended)

Venus Express is the first Venus exploration mission of the European Space Agency. It is currently in orbit around Venus and collecting scientific data.

Contents

[edit] History

The mission was proposed in 2001 to reuse the design of the Mars Express mission. However, some mission characteristics led to design changes: primarily in the areas of thermal control, communications and electrical power. For example, since Mars is approximately twice as far from the Sun as Venus is, the radiant heating of the spacecraft will be four times greater for Venus Express than Mars Express. Also, the ionizing radiation environment will be harsher. On the other hand, the more intense illumination of the solar panels will result in more generated photovoltaic power. The Venus Express mission also uses some spare instruments developed for the Rosetta spacecraft. The mission was proposed by Jet Propulsion Laboratory's Kevin Baines, who also worked on Cassini and New Horizons, and co-investigator on Venus Express' VIRTIS instrument.

The launch window for Venus Express was open from 26 October to 23 November 2005, with the launch initially set for 04:43 UT on 26 October. However, problems with the insulation from the Fregat upper stage led to a two week launch delay to inspect and clear out the small insulation debris that migrated on the spacecraft.[1] It was eventually launched by a Soyuz-Fregat rocket from the Baikonur Cosmodrome in Kazakhstan on 9 November 2005 at 03:33:34 UT into a parking Earth orbit and 1 h 36 min after launch put into its transfer orbit to Venus. A first trajectory correction maneuver was successfully performed on 11 November 2005. It arrived at Venus on April 11, 2006, after approximately 150 days of journey, and fired its main engine between 07:10 and 08:00 Universal Time (UT) to reduce its velocity so that it could be captured by Venusian gravity into a nine day orbit. The burn was monitored from ESA's Control Centre, ESOC, in Darmstadt, Germany.

Seven further orbit control maneuvers, two with the main engine and five with the thrusters, were required for Venus Express to reach its final operational 24-hour orbit around Venus.

Venus Express entered its target orbit at apocentre on 7 May 2006 at 13:31 UT, when the spacecraft was at 151 million kilometres from Earth. Now the spacecraft is running on an ellipse substantially closer to the planet than during the initial orbit. The orbit now ranges between 66,000 and 250 kilometres over Venus and it is polar. The pericentre is located almost above the North pole (80º North latitude), and it takes 24 hours for the spacecraft to travel around the planet.

Venus Express will study the Venusian atmosphere and clouds in detail, the plasma environment and the surface characteristics of Venus from orbit. It will also make global maps of the Venusian surface temperatures. Its nominal mission was originally planned to last for 500 Earth days (approximately two Venusian days), but the mission was extended on the 28th of February 2007, and will now continue until early May 2009. On-board resources are sized for an additional 500 Earth days.

Venus Express is outfitted mostly with spare parts and designs from the Mars Express and Rosetta missions, but has been adapted to cope with the high radiation and thermal environment surrounding Venus.

ASPERA-4: An acronym for "Analyzer of Space Plasmas and Energetic Atoms," ASPERA-4 will investigate the interaction between the solar wind and the Venusian atmosphere, determine the impact of plasma processes on the atmosphere, determine global distribution of plasma and neutral gas, study energetic neutral atoms, ions and electrons, and analyze other aspects of the near Venus environment. ASPERA-4 is a re-use of the ASPERA-3 design used on Mars Express, but adapted for the harsher near-Venus environment.

MAG: The magnetometer is designed to measure the strength of Venus's magnetic field and the direction of it as affected by the solar wind and Venus itself. It will be able to map the magnetosheath, magnetotail, ionosphere, and magnetic barrier in high resolution in three-dimensions, aid ASPERA-4 in the study of the interaction of the solar wind with the atmosphere of Venus, identify the boundaries between plasma regions, and carry planetary observations as well (such as for lightning). MAG is derived from the Rosetta lander's ROMAP instrument.

PFS: The "Planetary Fourier Spectrometer" operates in the infrared between the 0.9 µm and 45 µm wavelength range and is designed to perform vertical optical sounding of the Venus atmosphere. It will perform global, long-term monitoring of the three-dimensional temperature field in the lower atmosphere (cloud level up to 100 kilometers). Furthermore it will search for minor atmospheric constituents that may be present, but have not yet been detected, analyze atmospheric aerosols, and investigate surface to atmosphere exchange processes. The design is based on a spectrometer on Mars Express, but modified for optimal performance for the Venus Express mission.

SPICAV: Short for "Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus," SPICAV is an imaging spectrometer that will be used for analyzing radiation in the infrared and ultraviolet wavelengths. It is derived from the SPICAM instrument flown on Mars Express. However, SPICAV has an additional channel known as SOIR (Solar Occultation at Infrared) that will be used to observe the Sun through Venus's atmosphere in the infrared.

VeRa: Venus Radio Science is a radio sounding experiment that will transmit radio waves from the spacecraft and pass them through the atmosphere or reflect them off the surface. These radio waves will be received by a ground station on Earth for analysis of the ionosphere, atmosphere and surface of Venus. It is derived from the Radio Science Investigation instrument flown on Rosetta.

VIRTIS: VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) is an imaging spectrometer that observes in the near-ultraviolet, visible, and infrared parts of the electromagnetic spectrum. It will analyze all layers of the atmosphere, surface temperature and surface/atmosphere interaction phenomena.

VMC: The Venus Monitoring Camera is a wide-angle, multi-channel CCD. The VMC is designed for global imaging of the planet.[2] It operates in the visible, ultraviolet, and near infrared spectral ranges, and maps surface brightness distribution searching for volcanic activity, monitoring airglow, studying the distribution of unknown ultraviolet absorbing phenomenon at the cloud-tops, and making other science observations. It is derived in part by the Mars Express High Resolution Stereo Camera (HRSC) and the Rosetta Optical, Spectroscopic and Infrared Remote Imaging System (OSIRIS). The camera includes an FPGA to pre-process image data, reducing the amount transmitted to Earth.[3] The consortium of institutions responsible for the VMC includes the Max Planck Institute for Solar System Research, the Institute of Planetary Research at the German Aerospace Center and the Institute of Computer and Communication Network Engineering at Technische Universität Braunschweig.[4]

[edit] Important events and discoveries

spacecraft time (UT) ground receive time (UT)
Liquid Settling Phase start 07:07:56 07:14:41
VOI main engine start 07:10:29 07:17:14
pericentre passage 07:36:35
eclipse start 07:37:46
occultation start 07:38:30 07:45:15
occultation end 07:48:29 07:55:14
eclipse end 07:55:11
VOI burn end 08:00:42 08:07:28
Period of this orbit is nine days.
  • April 13, 2006: First images of Venus from Venus Express released.
  • April 20, 2006: Apocentre Lowering Manoeuvre #1 performed. Orbital period is now 40 hours.
  • April 23, 2006: Apocentre Lowering Manoeuvre #2 performed. Orbital period is now approx 25 hours 43 minutes.
  • April 26, 2006: Apocentre Lowering Manoeuvre #3 is slight fix to previous ALM.
  • May 7, 2006: Venus Express entered its target orbit at apocentre at 13:31 UT
  • December 14, 2006: First temperature map of the southern hemisphere.
  • February 27, 2007: ESA agrees to fund mission extension until May 2009.
  • September 19, 2007: End of the nominal mission (500 Earth days) - Start of mission extension.
  • November 27, 2007: The scientific journal Nature publishes a series of papers giving the initial findings. It finds evidence for past oceans. It confirms the presence of lightning on Venus and that it is more common on Venus than it is on Earth. It also reports the discovery that a huge double atmospheric vortex exists at the south pole of the planet. [6] [7]
  • May 20, 2008: The detection by the VIRTIS instrument on Venus Express of hydroxyl (OH) in the atmosphere of Venus is reported in the in the May 2008 issue of Astronomy and Astrophysics.[8]

[edit] See also

[edit] References

  1. ^ Venus Express preliminary investigations bring encouraging news. ESA (25 October 2005). Retrieved on 2006-05-09.
  2. ^ The Venus Express mission camera. Max Planck Institute for Solar System Research.
  3. ^ Venus Monitoring Camera. Technical University at Brunswick.
  4. ^ The light and dark of Venus. ESA (2008-02-21).
  5. ^ Successful Venus Express main engine test. ESA (17 February 2006). Retrieved on 2006-05-09.
  6. ^ Various authors (November 2007). "". Nature (450): 633 - 660. doi:10.1038/news.2007.297. 
  7. ^ Venus offers Earth climate clues. BBC News. Retrieved on 2007-11-29.
  8. ^ Venus Express Provides First Detection Of Hydroxyl In Atmosphere Of Venus. SpaceDaily.

[edit] External links

v • d • e
Spacecraft missions to Venus
Flybys
Venera 1 · Mariner 2 · Zond 1 · Venera 2 · Mariner 5 · 10 · Venera 11 · 12 · 13 · 14 · Vega 1 · 2 · Galileo · Cassini-Huygens · MESSENGER
Orbiters
Venera 9 · 10 · Pioneer Venus Orbiter · Venera 15 · 16 · Magellan · Venus Express
Descent probes
Landers
Venera 7 · 8 · 9 · 10 · 11 · 12 · 13 · 14 · Vega 1 · 2
Balloon probes
Vega 1 · 2
Future missions
PLANET-C (2010) · BepiColombo · Venus Entry Probe (2013) · Venera-D (2016)
See also
Bold italics indicates active missions