Invisible Cloud Features

Image source
Credit: ESA/ MPS/DLR/IDA

I've mentioned that Venus, with its obscuring sepia clouds, is one of the most boring worlds you'll ever see from space. That is, unless you're looking in the ultraviolet, in which case the dazzling complexity of its noxious, high-pressure, thoroughly greenhouse effected atmosphere is plain to see. Read more here.

MESSENGER at Venus

It seems that MESSENGER has successfully completed its gravity assist at (perhaps 'using' would be a better term) Venus. The mission homepage sums up the event nicely:

NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft swung by Venus for the second time early this evening [5th June] for a gravity assist that shrank the radius of its orbit around the Sun, pulling it closer to Mercury. At nearly 15,000 miles per hour, this change in MESSENGER’s velocity is the largest of the mission

[...]

According to APL’s Eric Finnegan, MESSENGER systems engineer, the spacecraft’s approach geometry is similar to that for the first Mercury flyby, allowing — for the first time in flight — the craft’s seven instruments to be turned on and operated collectively in science-observing mode, just as they will be for Mercury. “Gathering approximately six gigabits of data, the spacecraft will take more than 630 images, as well as make other scientific observations over the next few days,” Finnegan said.

In the news article at the Planetary Society, here, we learn that, like New Horizons at Jupiter, MESSENGER is currently something of a fish out of water. Just as New Horizons was designed to operate on the inner fringe of the Kuiper Belt, where sunlight is a precious commodity, so MESSENGER is intended to orbit Mercury, bathed in intense radiation. Venus may be a little on the dark side as far as its cameras are concerned, so it remains to be seen how interesting any images MESSENGER returns from Venus will be, especially given that, with its dense, sepia clouds, Venus isn't exactly the most photogenic world in the first place.

Still, I'll be sure to let you know if any pretty pictures make their appearance...

Venus Express, 1st Anniversary

Image source and description.
Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

I must admit, I had forgotten all about ESA mission Venus Express. Small wonder: they've released little information and only 8 images, the last four doled out to celebrate its first anniversary today: one Earth year orbiting Venus. Good thing then, that we have the Planetary Society Blog to draw our attention to it.

You can read the news item here at the Venus Express homepage, including some of the things we've learned about this cloudy, noxious world.

It's also well worth checking out Emily Lakdawalla's post on it at the Planetary Society Blog here. It seems that Venus may get a little interesting over the next couple of months, as MESSENGER will be using the planet for a gravity assist (in this case trying to lose momentum*), and there is going to be some co-ordinated science from the two probes.

*This is the momentum that the spacecraft starts with merely by virtue of being launched from the Earth, which is farther from the sun than Mercury. You can find a slightly more thorough description of this here. By the way, if you don't think reaching Mercury sounds very hard, take a look at the route MESSENGER will be taking. Basically - and this is nudging into territory that I always mean to learn more about but never get around to - it will have started out with an orbit around the sun pretty much the same as the Earth's, and the problem is shrinking that orbit down to reach Mercury's. (The most difficult part of spaceflight is that you can't reach anything by moving in a straight line.)