Venus Express

Infobox_Spacecraft
Name = Venus Express


Caption = 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 = November 9 2005
Launch_Vehicle = Soyuz-Fregat
Decay =
Mission_Duration = Cruise Earth to Venus: 150 days; in-orbit around Venus: 1000 days
Mass = 1270 kg
NSSDC_ID = 2005-045A
Semimajor_Axis = 39468.195 km (intended)
Eccentricity = 0.8403 (intended)
Inclination = 89.99 deg (intended)
Orbital_Period = 24 h (intended)
RA of ascending node = 107.277 deg (intended)
Argument of pericentre = 101.339 deg (intended)
True Anomaly = 0 (intended)
Webpage = [http://www.esa.int/SPECIALS/Venus_Express/ Venus Express (ESA)]
Orbital_elements = yes
Apoapsis =
Periapsis =

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

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. [cite web| url=http://www.esa.int/SPECIALS/Venus_Express/SEM2714J2FE_0.html|title=Venus Express preliminary investigations bring encouraging news| date=25 October 2005| publisher=ESA| accessdate=2006-05-09] 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 (80° 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 years), but the mission was extended on February 28 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.

Instruments

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.

VMC: The Venus Monitoring Camera is a wide-angle, multi-channel CCD. The VMC is designed for global imaging of the planet. [cite web |url=http://www.mps.mpg.de/en/projekte/venus-express/vmc/ |title=The Venus Express mission camera |publisher=Max Planck Institute for Solar System Research] 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. [cite web |url=http://www.ida.ing.tu-bs.de/index.php?id=841&L=2. |title=Venus Monitoring Camera |publisher=Technical University at Brunswick] 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. [cite web |url=http://www.esa.int/esaCP/SEMIVTVHJCF_index_0.html |title=The light and dark of Venus |date=2008-02-21 |publisher=ESA]

Magnetometer

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.

pectrometer

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.

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.

Radio science

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".

Search for life on Earth

Venus Express is used also to observe signs of life on Earth from the Venus orbit. In the pictures Earth is less than one pixels in size which mimics observetions of Earth-sized planets on different solarsystems. These observations are then used to develop methods to habitability studies of extra-Solar planets. [ [http://www.esa.int/esaCP/SEMUOW4N0MF_index_0.html Venus Express searching for life – on Earth] ESA]

Important events and discoveries

*August 3 2005: Venus Express completed its final phase of testing at Astrium Intespace facility in Toulouse, France. It flew on a Antonov An-124 cargo aircraft via Moscow, before arriving at Baikonur on 7 August.
*August 7 2005: Venus Express arrived at the airport of the Baikonur Cosmodrome.
*August 16 2005: First flight verification test completed.
*August 22 2005: Integrated System Test-3.
*August 30 2005: Last Major System Test Successfully Started.
*September 5 2005: Electrical Testing Successful.
*September 21 2005: FRR (Fuelling Readiness Review) Ongoing.
*October 12 2005: Mating to the Fregat upper stage completed.
*October 21 2005: Contamination detected inside the fairing — launch on hold.
*November 5 2005: Arrival at launch pad.
*November 9 2005: Launch from Baikonur Cosmodrome at 3:33 UT.
*November 11 2005: First trajectory correction maneuver successfully performed.
*February 17 2006: The main engine is fired successfully in a dress rehearsal for the arrival maneuver. [cite web| url=http://www.esa.int/SPECIALS/Venus_Express/SEMVX5MVGJE_0.html| title=Successful Venus Express main engine test| date=17 February 2006| publisher=ESA| accessdate=2006-05-09]
*February 24 2006: Second trajectory correction maneuver successfully performed.
*March 29 2006: Third trajectory correction maneuver successfully performed - on target for April 11 orbit insertion.
*April 7 2006: Command stack for orbit insertion maneuver is loaded on the spacecraft.
*April 11 2006: The Venus Orbit Insertion (VOI) is completed successfully, according to the following timeline:

::

:::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. [cite journal |last=Various authors |first= |authorlink= |coauthors= |year=2007 |month=November |title= European mission reports from Venus|journal=Nature |volume= |issue=450 |pages=633–660 |id= |doi= 10.1038/news.2007.297 |accessdate= 2007-11-29 |quote= ] [cite web |url=http://news.bbc.co.uk/1/hi/sci/tech/7117303.stm |title=Venus offers Earth climate clues |accessdate=2007-11-29 |format= |work=BBC News ]
*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. [cite web |url=http://www.spacedaily.com/reports/Venus_Express_Provides_First_Detection_Of_Hydroxyl_In_Atmosphere_Of_Venus_999.html |title=Venus Express Provides First Detection Of Hydroxyl In Atmosphere Of Venus |publisher=SpaceDaily]

ee also

* Unmanned space mission
* Geosynchronous satellite
* List of planetary probes
* List of unmanned spacecraft by program
* Satellite
* Space exploration
* Space observatory
* Space probe
* Timeline of artificial satellites and space probes
* Timeline of planetary exploration

References

*20 articles in Planetary and Space Science cite journal| author = F.W. Taylor | title = The Planet Venus and the Venus Express Mission, The Planet Venus and the Venus Express Mission | journal = Planetary and Space Science | volume = 54 | issues = 13-14| pages = 1247–1496 | year = 2006| doi = 10.1016/j.pss.2006.06.013
*cite web | title="Venus Express" launch campaign starts | work=ESA Portal | url=http://www.esa.int/esaCP/SEMMDL808BE_index_0.html | accessdaymonth=3 August | accessyear=2005
*cite web | title="Venus Express" Launch Campaign Journal| work=ESA SciTech Website | url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31574&farchive_objecttypeid=31&farchive_objectid=30928 | accessdaymonth=16 August | accessyear=2005
*cite web | title="Venus Express" 3D Model| work=ESA SciTech Website | url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=35192 | accessdaymonth=5 September | accessyear=2005
*cite web | title="Venus Express" Instruments| work=ESA Portal | url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33964 | accessdaymonth=14 September | accessyear=2005

External links

* [http://www.esa.int/SPECIALS/Venus_Express/ ESA description of the "Venus Express" mission]
* [http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39060 ESA Science & Technology] - Venus Express page
* [http://www.esa.int/SPECIALS/Operations/SEM7QMQJNVE_0.html ESA Spacecraft Operations] - Venus Express page
* [http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Venus_Express Venus Express Program Page] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]
* [http://www.ajax.ehu.es/VEX/ Venus Express: The first European mission to Venus]
* [http://www.extrasolar-planets.com/eng/venus_express.php Extrasolar-planets.com — Venus Express]
* [http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38947 Orbit Insertion] - Scheduled events to shape orbit concluding May 6, 2006
* [http://www.esa.int/SPECIALS/Venus_Express/SEM4KXPJNVE_1.html Map of temperatures of South Hemisphere of Venus planet]
* [http://www.space-astronautics.com/03 apr 2007-esa-1.html 04/03/07: Venus Express: Tracking Violent Winds and Turbulences] Site includes full coverage of the Venus Express Mission
* [http://starrymirror.com/venusamateursnov22.htm Amateurs Assist Venus Express Mission]