Six years of observations by ESA’s Venus Express have shown large changes in the sulphur dioxide content of the planet’s atmosphere, and one intriguing possible explanation is volcanic eruptions. The thick atmosphere of Venus contains over a million times as much sulphur dioxide as Earth’s, where almost all of the pungent, toxic gas is generated by volcanic activity.
An extension to the operations of Venus Express until 2015 was also approved, subject to a mid-term review and confirmation by SPC in 2014. This extension will allow an aerobraking campaign to be carried out within the timescale permitted by the remaining fuel on board.The next mission extension cycle will begin in mid-2014.
Aerobraking and end of Venus Express misiónAfter more than 10 years in orbit around Venus, the Venus Express mission will come to an end. Before the spacecraft runs out of fuel, it will be manoeuvred into the tenuous upper atmosphere of the planet, where it will conduct unique science while making engineering tests of aerobraking, potentially useful for future ESA missions. The mission will end as the spacecraft descends into denser atmospheric layers and burns up. Location: TBDExpected date: June
After eight years in orbit, ESA’s Venus Express has completed routine science observations and is preparing for a daring plunge into the planet’s hostile atmosphere.
http://www.esa.int/Our_Activities/Space_Science/Venus_Express/Venus_Express_gets_ready_to_take_the_plungeQuoteAfter eight years in orbit, ESA’s Venus Express has completed routine science observations and is preparing for a daring plunge into the planet’s hostile atmosphere.
The 25th aerobraking orbit (Number 2975 in the mission overall) was completed earlier today; on 11 June, during orbit 2973, the spacecraft dipped down to almost 140 km above the Venusian surface – an unprecedented low altitude.
On board Venus express, everything is functioning as expected and within limits: power, propulsion, communications, temperatures of spacecraft components, & etc.
The walk-in phase finishes today, and we are officially starting the aerobraking phase. Current pericentre altitude is around 136km, and we will drop naturally about 1km over the next week after which the pericentre altitude remains nominally constant [at about 135 km] to the end of aerobraking on 11 July.
the mission operations team at ESOC used the spacecraft's thrusters today to lower the pericentre altitude by 2.8 km; this pericentre-lowering manoeuvre (think of it as a 'push-down' manoeuvre) was done by firing the thrusters as Venus Express passed through apocentre. The thruster burn took place at 12:42 CEST (10:42 UTC), and the next - and unprecedented low - pericentre pass will now occur at 00:31 CEST on 24 June (22:31 UTC on 23.06). The manoeuvre should bring pressures to 0.4 N/m^2 by the mid-point of the aerobraking plateau on 29 June.
Yesterday morning, 2 July, the spacecraft performed another manoeuvre designed to lower the pericentre altitude by 0.8 km.This pericentre lowering is being performed in order to target higher atmospheric densities; the highest dynamic pressure (drag force) experienced by the spacecraft so far is 0.45 N/m2; the VEX team is aiming higher, trying to reach dynamic pressures of over 0.50 N/m^2. Atmospheric density at pericentre can vary by over 30% from one orbit to the next, making it difficult to know what atmospheric density will be reached on the next aerobraking pass...
Venus Express is now in the final week of its aerobraking campaign, and is about as low as it’s going to get. At its last pericentre passage, its altitude was only 129.9 km and this is expected to decrease to 129.1 km before the end of the aerobraking campaign.
... you may have noticed in the plots that Venus Express has reached its 3000th pericentre, in other words it has completed 3000 orbits around Venus (it reached this milestone on Monday 7 July). Reaching this milestone is especially impressive given that the spacecraft was originally designed for a nominal science mission of only 500 orbits!
After a month surfing in and out of the atmosphere of Venus down to just 130 km from the planet’s surface, ESA’s Venus Express is about to embark on a 15 day climb up to the lofty heights of 460 km.