The ESA is having a lot of success as of late. First in viewing a comet and also their recent successes as it relates to orbiting Venus at an altitude of 130km (FYI – the same altitude Virgin Galactic takes you to in Earth’s orbit) and since dropped and gained and dropped again. Since every is giving details on Rosetta here is some data about the Venus Express.
This mission took eight long years (and they call it Express!) and Rosetta took ten – in retrospect the ESA has the patience it requires to master space. This mission (Venus) is quite unique and risk; Venus’ atmosphere is not the most welcoming.
As the only spacecraft to take up residence around Venus, the Venus Express arrived in April of 2006. The word is ‘arrived’ and not landed as it has been circling and gathering data regarding the planet’s atmosphere but with time running out as its fuel tank approached empty the mission team made a decision. The Venus Express will undergo a series of aerobraking campaigns – each sending the orbiter deeper and deeper into the atmosphere.
The Venus Express will likely run out of fuel this December and plunge itself into the depths of Venus’s forbidden planet. Once so like Earth but a runaway greenhouse effect has altered its surface from what it once was.
What sort of data has the orbiter received? In reference to its atmospheric density more than 30 atmospheric profiles were gathered and the atmospheric density was sampled 55 times. From this data the following observations can be made; extreme heating cycles exist with temperatures varying from -50 Celsius to 50 Celsius – a rise of 100 degrees, additionally the atmosphere is 1,000 times more dense between the altitudes of 165km and 130km. This has not yet been correlated to features on the ground but the team is now investigating that.
Also - a drastic change in density was realized quickly as the spacecraft moves from the daylight into the darkness. Drastic that can be quantified - about 4 times greater on the dayside versus the nightside.
Part of the learning that the Venus Express has provided will helped the ESA (the world really) to understand an individual spacecrafts response to rapid heating. This will be very useful to all missions to all places!
Another useful area where much was leaned was Aerobraking-a maneuver used to slow a spacecraft approaching a planet or moon with an atmosphere and allowing it to be captured in its orbit and move from an elliptical orbit to one that is more circular. This has a side benefit of requiring less fuel always a plus in space travel.
Recently observations were made by Venus Express – emissions of green light from the oxygen atoms in Venus’s atmosphere that were stirred up by charged particles expelled from the Sun. During this time the oxygen atoms dropped significantly in altitude from 140 km t0 120 km which is suggestive of an aurora. Oddly enough this is very similar to Earth which displays a similar auroral event referred to as the northern lights.
Venus is home to a weak magnetic field whereas on Earth the magnetic field is much stronger.