Venus Express

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Venus Express
Venus Express in orbit (crop).jpg
Venus Express in orbit
Mission type Venus orbiter
Operator European Space Agency
COSPAR ID 2005-045A OOjs UI icon edit-ltr-progressive.svg
SATCAT no. 28901
Website www.esa.int/venus
Mission durationPlanned: 2 years
Final: 9 years, 2 months, 9 days
Spacecraft properties
Manufacturer EADS Astrium
Launch mass1,270 kg (2,800 lb) [1]
Dry mass700 kg (1,543 lb) [1]
Payload mass93 kg (205 lb) [1]
Dimensions1.5 × 1.8 × 1.4 m (4.9 × 5.9 × 4.6 ft) [1]
Power1,100 watts [1]
Start of mission
Launch date9 November 2005, 03:33:34 (2005-11-09UTC03:33:34)  UTC [2]
Rocket Soyuz-FG/Fregat
Launch site Baikonur 31/6
Contractor Starsem
End of mission
DisposalDeorbited
Last contact18 January 2015, 15:01:55 (2015-01-18UTC15:01:56)  UTC [3]
Decay dateJanuary /February 2015
Orbital parameters
Reference system Cytherocentric
Pericytherion altitude 460 km (290 mi) [4]
Apocytherion altitude 63,000 km (39,000 mi) [4]
Inclination 90 degrees [5]
Period 24 hours [5]
Venus orbiter
Orbital insertion11 April 2006
Venus Express insignia.png
ESA Solar System insignia for the Venus Express mission  

Venus Express (VEX) was the first Venus exploration mission of the European Space Agency (ESA). Launched in November 2005, it arrived at Venus in April 2006 and began continuously sending back science data from its polar orbit around Venus. Equipped with seven scientific instruments, the main objective of the mission was the long term observation of the Venusian atmosphere. The observation over such long periods of time had never been done in previous missions to Venus, and was key to a better understanding of the atmospheric dynamics. ESA concluded the mission in December 2014. [6]

Contents

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, the radiant heating of the spacecraft is four times greater for Venus Express than Mars Express. Also, the ionizing radiation environment is harsher. On the other hand, the more intense illumination of the solar panels results in more generated photovoltaic power. The Venus Express mission also uses some spare instruments developed for the Rosetta spacecraft. The mission was proposed by a consortium led by D. Titov (Germany), E. Lellouch (France) and F. Taylor (United Kingdom).

The launch window for Venus Express was open from 26 October to 23 November 2005, with the launch initially set for 26 October 4:43 UTC. 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. [7] It was eventually launched by a Soyuz-FG/Fregat rocket from the Baikonur Cosmodrome in Kazakhstan on 9 November 2005 at 03:33:34 UTC 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 11 April 2006, after 153 days of journey, and fired its main engine between 07:10:29 and 08:00:42 UTC SCET to reduce its velocity so that it could be captured by Venusian gravity into a nine-day orbit of 400 by 330,000 kilometres (250 by 205,050 mi). [8] 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. [8]

Venus Express entered its target orbit at apoapsis on 7 May 2006 at 13:31 UTC, when the spacecraft was 151,000,000 kilometres (94,000,000 mi) from Earth. At this point the spacecraft was running on an ellipse substantially closer to the planet than during the initial orbit. The polar orbit ranged between 250 and 66,000 kilometres (160 and 41,010 mi) over Venus. The periapsis was located almost above the North pole (80° North latitude), and it took 24 hours for the spacecraft to travel around the planet.

Venus Express studied the Venusian atmosphere and clouds in detail, the plasma environment and the surface characteristics of Venus from orbit. It also made global maps of the Venusian surface temperatures. Its nominal mission was originally planned to last for 500 Earth days (approximately two Venusian sidereal days), but the mission was extended five times: first on 28 February 2007 until early May 2009; then on 4 February 2009 until 31 December 2009; and then on 7 October 2009 until 31 December 2012. [9] On 22 November 2010, the mission was extended to 2014. [10] On 20 June 2013, the mission was extended a final time until 2015. [11]

On 28 November 2014, mission control lost contact with Venus Express. Intermittent contact was reestablished on 3 December 2014, though there was no control over the spacecraft, likely due to exhaustion of propellant. [12] On 16 December 2014, ESA announced that the Venus Express mission had ended. [6] A carrier signal was still being received from the vehicle, but no data was being transmitted. Mission manager Patrick Martin expected the spacecraft would fall below 150 kilometres (93 mi) in early January 2015, with destruction occurring in late January or early February. [13] The spacecraft's carrier signal was last detected by ESA on 18 January 2015. [3]

Instruments

ASPERA-4: An acronym for "Analyzer of Space Plasmas and Energetic Atoms," ASPERA-4 investigated 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 was 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 mapped 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 the search for and characterization of Venus lightning). MAG was derived from the Rosetta lander's ROMAP instrument.

One measuring device was placed on the body of the craft. The identical second of the pair was placed the necessary distance away from the body by unfolding a 1 m long boom (carbon composite tube). Two redundant pyrotechnical cutters cut one loop of thin rope to free the power of metal springs. The driven knee lever rotated the boom perpendicularly outwards and latched it in place. Only the use of a pair of sensors together with the rotation of the probe allowed the spacecraft to resolve the small natural magnetic field beneath the disturbing fields of the probe itself. The measurements to identify the fields produced by the craft took place on the route from Earth to Venus. [14] [15] The lack of magnetic cleanness was due to the reuse of the Mars Express spacecraft bus, which did not carry a magnetometer. [15] By combining the data from two-point simultaneous measurements and using software to identify and remove interference generated by Venus Express itself, it was possible to obtain results of a quality comparable to those produced by a magnetically clean craft. [15]

VMC: The Venus Monitoring Camera is a wide-angle, multi-channel CCD. The VMC is designed for global imaging of the planet. [16] It operated in the visible (VIS), ultraviolet (UV), and near infrared (NIR1 and NIR2) 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 was derived in part from the Mars Express High Resolution Stereo Camera (HRSC) and the Rosetta Optical, Spectroscopic and Infrared Remote Imaging System (OSIRIS). The camera is based on a Kodak KAI-1010 Series, 1024 x 1024 pixel interline CCD, and included an FPGA to pre-process image data, reducing the amount transmitted to Earth. [17] [18] The consortium of institutions responsible for the VMC included 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. [19] It is not to be confused with Visual Monitoring Camera mounted on Mars Express , of which it is an evolution. [17] [20]

Venus Monitoring Camera channels [17]
VMC ChannelCentral WavelengthSpectral Range
VIS513 nm503 – 523 nm
NIR1935 nm900 – 970 nm
NIR21.01 µm990 – 1030 nm
UV365 nm345 – 385 nm

PFS: The "Planetary Fourier Spectrometer" (PFS) should have operated in the infrared between the 0.9  µm and 45 µm wavelength range and was designed to perform vertical optical sounding of the Venus atmosphere. It should have performed global, long-term monitoring of the three-dimensional temperature field in the lower atmosphere (cloud level up to 100 kilometers). Furthermore, it should have searched for minor atmospheric constituents that may be present, but had not yet been detected, analyzed atmospheric aerosols, and investigated surface to atmosphere exchange processes. The design was based on a spectrometer on Mars Express, but modified for optimal performance for the Venus Express mission. However PFS failed during its deployment and no useful data was transmitted. [21]

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

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

VeRa: Venus Radio Science was a radio sounding experiment that transmitted radio waves from the spacecraft and passed them through the atmosphere or reflected them off the surface. These radio waves were received by a ground station on Earth for analysis of the ionosphere, atmosphere and surface of Venus. It was derived from the Radio Science Investigation instrument flown on Rosetta .

Science

Climate of Venus

Starting out in the early planetary system with similar sizes and chemical compositions, the histories of Venus and Earth have diverged in spectacular fashion. It is hoped that the Venus Express mission data that was obtained can contribute not only to an in-depth understanding of how the Venusian atmosphere is structured, but also to an understanding of the changes that led to the current greenhouse atmospheric conditions. Such an understanding may contribute to the study of climate change on Earth. [22] [ needs update ]

Search for life on Earth

Venus Express was also used to observe signs of life on Earth from Venus orbit. In images acquired by the probe, Earth was less than one pixel in size, which mimics observations of Earth-sized planets in other planetary systems. These observations were then used to develop methods for habitability studies of exoplanets. [23]

Timeline of the mission

Animation of Venus Express's trajectory from 9 November 2005 to 31 December 2006 .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{} Venus Express * Venus * Earth * Sun Animation of Venus Express trajectory.gif
Animation of Venus Express's trajectory from 9 November 2005 to 31 December 2006
  Venus Express ·  Venus ·  Earth ·  Sun
Animation of Venus Express's trajectory around Venus from 1 April 2006 to 1 April 2008 Venus Express * Venus Animation of Venus Express trajectory around Venus.gif
Animation of Venus Express's trajectory around Venus from 1 April 2006 to 1 April 2008
  Venus Express ·  Venus
Event Spacecraft event time (UTC)Ground receive time (UTC)
Liquid Settling Phase start07:07:5607:14:41
VOI main engine start07:10:2907:17:14
periapsis passage07:36:35
eclipse start07:37:46
occultation start07:38:3007:45:15
occultation end07:48:2907:55:14
eclipse end07:55:11
VOI burn end08:00:4208:07:28
Period of this initial orbit is nine days. [8]

See also

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References

  1. 1 2 3 4 5 "Venus Express Factsheet". European Space Agency. 1 June 2014. Retrieved 5 July 2017.
  2. ↑ Siddiqi, Asif (2018). Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016 (PDF) (second ed.). NASA History Program Office.
  3. 1 2 3 Scuka, Daniel (23 January 2015). "Venus Express: The Last Shout". European Space Agency. Retrieved 26 January 2015.
  4. 1 2 "Venturing into the upper atmosphere of Venus". European Space Agency. 11 November 2014. Retrieved 23 November 2014.
  5. 1 2 "Operational Orbit". European Space Agency. 14 December 2012. Retrieved 23 November 2014.
  6. 1 2 3 Bauer, Markus; Svedhem, Håkan; Williams, Adam; Martin, Patrick (16 December 2014). "Venus Express goes gently into the night". European Space Agency. Retrieved 22 December 2014.
  7. ↑ "Venus Express preliminary investigations bring encouraging news". ESA. 25 October 2005. Retrieved 9 May 2006.
  8. 1 2 3 "Venus Express". National Space Science Data Center . Retrieved 22 December 2014.
  9. ↑ "Mission extensions approved for science missions". ESA. 16 October 2009.
  10. ↑ "Europe maintains its presence on the final frontier". ESA. 22 November 2010.
  11. ↑ "ESA science missions continue in overtime". ESA. 20 June 2013.
  12. 1 2 3 "Venus Express anomaly". SpaceDaily. 8 December 2014. Retrieved 15 December 2014.
  13. ↑ Drake, Nadia (17 December 2014). "Out of Fuel, Venus Express Is Falling Gently to Its Death in Planet's Skies". National Geographic. Archived from the original on 18 December 2014. Retrieved 22 December 2014.
  14. ↑ "IWF : VEX-MAG". Iwf.oewa.ac.at. Archived from the original on 6 October 2014. Retrieved 15 December 2014.
  15. 1 2 3 Pope, S. A.; Zhang, T. L.; Balikhin, M. A.; Hvizdos, L.; Kudela, K.; Dimmock, A. P. (April 2011). "Exploring planetary magnetic environments using magnetically unclean spacecraft: A systems approach to VEX MAG data analysis". Annales Geophysicae. 29 (4): 639–647. Bibcode:2011AnGeo..29..639P. doi: 10.5194/angeo-29-639-2011 .
  16. ↑ "The Venus Express mission camera". Max Planck Institute for Solar System Research. Archived from the original on 7 March 2008.
  17. 1 2 3 Markiewicz, W. J.; Titov, D.; Fiethe, B.; Behnke, T.; Szemerey, I.; et al. "Venus Monitoring Camera for Venus Express" (PDF). Max Planck Institute for Solar System Research. Archived from the original (PDF) on 2 April 2015.
  18. ↑ "Venus Monitoring Camera". Technical University at Brunswick.
  19. ↑ "The light and dark of Venus". ESA. 21 February 2008.
  20. ↑ Koeck, Ch.; Kemble, S.; Gautret, L.; Renard, P.; Faye, F. (October 2001). "Venus Express: Mission Definition Report" (PDF). European Space Agency. p. 17. ESA-SCI(2001)6.
  21. ↑ Lakdawalla, Emily (23 July 2007). "Venus Express PFS fails to respond to a swift kick". The Planetary Society. Retrieved 2 February 2023.
  22. ↑ "Atmospheric Dynamics of Venus and Earth" (PDF). Lpi.usra.edu. Retrieved 15 December 2014.
  23. ↑ "Venus Express searching for life – on Earth". European Space Agency. Retrieved 15 December 2014.
  24. ↑ "Successful Venus Express main engine test". European Space Agency. 17 February 2006. Retrieved 9 May 2006.
  25. ↑ "Venus orbit insertion". European Space Agency. 24 May 2007. Retrieved 26 January 2015.
  26. ↑ "The new temperature map of Venus' southern hemisphere". European Space Agency. 14 July 2009. Retrieved 27 November 2016.
  27. ↑ Hand, Eric (27 November 2007). "European mission reports from Venus". Nature . doi: 10.1038/news.2007.297 . S2CID   129514118.
  28. ↑ "Venus offers Earth climate clues". BBC News. 28 November 2007. Retrieved 29 November 2007.
  29. ↑ "Venus Express Provides First Detection of Hydroxyl in Atmosphere of Venus". SpaceDaily. 20 May 2008. Retrieved 15 December 2014.
  30. ↑ Carpenter, Jennifer (7 October 2011). "Venus springs ozone layer surprise". BBC News.
  31. ↑ Montmessin, F.; Bertaux, J.-L.; Lefèvre, F.; Marcq, E.; Belyaev, D.; et al. (November 2011). "A layer of ozone detected in the nightside upper atmosphere of Venus". Icarus. 216 (1): 82–85. Bibcode:2011Icar..216...82M. doi:10.1016/j.icarus.2011.08.010. hdl:2268/100136.
  32. ↑ "A curious cold layer in the atmosphere of Venus". European Space Agency. 1 October 2012. Retrieved 15 December 2014.
  33. ↑ Scuka, Daniel (16 May 2014). "Surfing an alien atmosphere". European Space Agency. Retrieved 23 November 2014.
  34. ↑ "Venus Express rises again". European Space Agency. 11 July 2014. Retrieved 14 April 2015.

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