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Well, it’s been quite the week for solar system exploration!
As I write this, the European spacecraft Venus Express is just three hours away from starting up the maneuvers it needs to enter orbit around Venus. If all goes well, at 01:07 Pacific time (08:07 Universal or Greenwich time) on April 11, the first spacecraft since Magellan will become a moon of the otherwise moonless planet.
As usual with planetary stuff, the best place to get info is Emily Lackdawalla’s Planetary Society Blog. She has a timeline there, and lots more about the spacecraft and its mission. You can also poke around The Nine Planets website for more too.
I’ll note that this mission is heavily designed to study Venus’s weird atmosphere. You’ve probably heard about it before: 90 times the Earth’s pressure, flaming hot due to a runaway greenhouse effect, sulphuric acid rain, no water. Weird hardly begins to describe it.
But I’ll leave you with this: if you are an early riser, go outside tomorrow morning and face just south of east. See that incredibly bright star, low in the sky? That’s it. That’s Venus. It’s almost exactly the same size as Earth, but enshrouded in clouds, making it highly reflective. So even at its current distance of 120 million kilometers, it’s the third brightest star in the sky.
120 million kilometers. And our grasp has once again reached out across the sky to touch another small piece of the Universe.’
April 10th, 2006 at 9:06 pm
I loved what I heard the other day, that this mission is only “two Venus days long.” And then how a “day” on Venus is a lot longer than a day on earth.
Can’t wait to see the data we get from that mission.
April 10th, 2006 at 9:33 pm
Wait…third brightest star, or third brightest object? I know the Sun is the brightest star…so what star is brighter than Venus?
April 10th, 2006 at 10:00 pm
I suppose “object” would have been more accurate. The Sun and Moon are the only two objects brighter.
April 11th, 2006 at 1:55 am
Venus Explorer is now in orbit! Bravo ESA!!
April 11th, 2006 at 3:02 am
Woohoo! May the solarwind be in your back! =]
April 11th, 2006 at 3:27 am
It is great that the United States is not the only country taking the lead on science missions to the planets.
April 11th, 2006 at 5:26 am
Umm, this statement confused me a bit: “sulphuric acid rain, no water.” As far as I know, water is a prerequisite for any acid. You just can’t have acid without water. You could have H2SO4 gas, but that wouldn’t be an acid, that’s just Hydrogen Sulphate gas.
April 11th, 2006 at 6:21 am
Sure, you can have acid without water. It comes in blotter form. Use responsibly.
Seriously, according to the definition, an acid is a substance which when dissolved in water donates protons, whereas a base is a proton acceptor. After the proton (a.k.a. hydrogen ion) is donated, the acid is “dissociated”.
April 11th, 2006 at 6:22 am
Oops, that paragraph was meant to read “according to the Brønsted-Lowry definition …” A preview button would solve all these problems, but I guess we should only ask for so many miracles in each day. (-:
April 11th, 2006 at 6:24 am
The definition of “acid” is “any substance with a PH of less than seven”. Water is NOT necessary.
April 11th, 2006 at 6:42 am
Before my attempts at fancy HTML screwed me up, I was trying to say that a substance without any water in it at all could be a perfectly legitimate acid. Pure liquid H2SO4 is an example. (Note that “pH” refers to the power of hydrogen, that is, the concentration of hydrogen ions (protons) in a solution. You’re still implicitly talking about water.)
April 11th, 2006 at 7:13 am
The first probe since Magellen? Wow, didn’t know it had been THAT long since anything had visited the greenhouse planet.
Here’s to the Venus Express!
April 11th, 2006 at 7:21 am
It’s great to see how the Europeans have the same “can-do” attitude that our JPL does. Getting these probes off the ground faster and cheaper is going to lead to all kinds of great new discoveries. Cool stuff!
April 11th, 2006 at 7:44 am
I was under the impression that a substance was only an acid when it was actually dissolved in water. What makes it an acid is that it reacts with the water to create hydronium ions and the respective negative ion for the particular acid (in the case of Sulphuric acid, (HSO4)-, some of which also reacts to form more hydronium ions and (SO4)2-). It is then the hydronium ions that react with whatever comes into contact with the acid. However, in pure H2SO4 (or HCl, or H3PO4, or HCO3, etc) There is no mechanism to separate the protons from the negative ions, so there is no way for them to actually become an acid. The substances can still react strongly with things they come into contact with, of course, but so do all kinds of other substances that aren’t acids. It’s the reaction with water to create the extremely reactive hydronium ions that causes it to be an acid.
And yes, the presence of water is implicit in the definition of pH: A solution with a given pH has 10^(-pH) moles of hydronium ions per liter of water.
April 11th, 2006 at 8:34 am
I’m not a chemist ( and it has been years since I’ve studied it and someone will certainly correct me if I’m wrong =), but I believe what you are describing is what happens when an acid reacts with water… not that the water renders the substance into an acid. Water, itself, can act as an acid or a base depending on the relative pH of other substances it comes in contact with. Also, an acid and a base reacts to form salts.
April 11th, 2006 at 11:31 am
It didn’t seem like Magellan was all that long ago — until it dawned on me that the mission launched about a month before I graduated from high school. Yikes. That’s been a while.
Can’t wait to see what VE will reveal with much better instrumentation.
Kudos to ESA for another job well-done.
April 11th, 2006 at 8:45 pm
I loved looking at Venus when it was in the night sky last winter. When will it return?
April 12th, 2006 at 2:09 pm
What about the moon? That’s got to be brighter than Venus. So would be the three brightest objects.
The Sun
The Moon
Venus