Messenger Spacecraft Prepared for Mercury 142
An anonymous reader writes "NASA's first orbiter to the planet Mercury is shown today in cut-away, revealing the parasol design that will protect it from intense heat. Twenty layers of aluminized Kapton will be its sunshade. Curiously since the innermost planet is so close to the Sun, the Mercury mission itself will look for (cometary) water-ice preserved on the less baked north pole."
The probe's slogan (Score:5, Funny)
Re:The probe's slogan (Score:2)
Re:Bright future my ass (Score:1, Funny)
Re:What bright future? (Score:3, Funny)
"I'm so frigging tire of sawing logs. I wonder if I could run one of those prophet scams without the Romans catching on?"
Is that even possible? (Score:5, Funny)
How can you keep the spacecraft at room temperature if everything around it is at least 212F? I need to get some of those fans for my computer.
Re:Is that even possible? (Score:1)
Re:Is that even possible? (Score:5, Informative)
It would be amazing if it was true that everything around the spacecraft was at 100C. But the side which doesn't face the sun A) doesn't need the sun shields, and B) sees the cold vacuum of space, a great place to passivly radiate unwanted heat to.
Check out this page [jhuapl.edu] from the MESSENGER site showing the sun shields only on the side facing the sun.
Re:Is that even possible? (Score:1)
See, I always thought that vacum was a BAD place to try to radiate heat to... Heat being a property of how active the molecules were. Vaccum, having nothing in it, doesn't transfer heat - which is why we have vaccum flasks, which keep hot things hot and cold things cold.
Of course, I'm not a science guy, so what do I know, right?
Re:Is that even possible? (Score:5, Informative)
Conduction and convection are not going to work in a vacuum, but radiation works just fine. This is electromagnetic radiation, like light and radio waves, so it does not need a medium.
Re:Is that even possible? (Score:1)
Cool.
Re:Is that even possible? (Score:2)
Re:Is that even possible? (Score:2, Interesting)
Which is why vacuum flasks also use silvered glass, to help reflect the infrared radiation back into your hot soup.
- Peter
Re:Is that even possible? (Score:5, Funny)
Apparently. I thought the energy from the sun reaching the earth through 150 million miles of hard vaccum might have been some clue.
Re:Is that even possible? (Score:3, Informative)
150 million kilometers, or 93 million miles.
Re:Is that even possible? (Score:2, Funny)
I do'nt kneed on dman pvriev buton!
Re:Is that even possible? (Score:1)
Re:Is that even possible? (Score:5, Informative)
Re:Is that even possible? (Score:3, Informative)
If an object only gets rid of heat only through electromagentic radiation, it's emissivity is one (this is a perfect blackbody), if it gets rid of heat through other means, the emissivity will be something less than one. Color is not relevent . . . radiation of heat is.
Note that for very hot objects, other methods of getting rid of heat can be assumed to be neg
Re:Is that even possible? (Score:2)
It is important to distinguish between reflectivity and emmissivity. The white color of an object that doesn't absorb radiation is a measurement of reflectivity. An object that doesn't absorb any radiation will have a reflectivity or albedo of 1, however, it's emissivity depends on how it disipates heat energy which has aboslutely nothing to do with reflectivity. Even if the object is white with a reflectivity of 1, if it produces its own heat, then it is emitt
Re:Is that even possible? (Score:3, Informative)
It's still an annoying problem, as radiators take up valuable surface area / FOV space which would preferable used for observational instrumentation.
Re:Is that even possible? (Score:4, Informative)
Re:Is that even possible? (Score:2)
Re:Is that even possible? (Score:1)
Ion drive (Score:2, Interesting)
Re:Ion drive (Score:5, Informative)
Trying to ride the 'wind' from your own ion drive is very similar to trying to windsurf by blowing into your own sail -- or, to use a more familiar analogy, pulling one's self up by one's own bootstraps.
Re:Ion drive (Score:2)
Ion drives derive thrust from ions (often caesium IIRC) escaping in the direction opposite to the required motion. That's why they are called ion drives. The ions don't have great mass, but they can be accelerated to very high speeds (close to the speed of light). This makes them very efficient, even though they only produce small amounts of thrust.
Re:Ion drive (Score:5, Informative)
For comparison purposes the best Isp from a chemical rocket system in use is pretty much Lox/H2 which gives you an Ispvac in the 460s range.
More info here: http://nmp.jpl.nasa.gov/ds1/tech/ionpropfaq.html [nasa.gov]
And yes, I am a rocket scientist.
Re:Ion drive (Score:2)
I believe you meant 300,000,000 m/s. Only off by an order of magnitude.
Re:Ion drive (Score:2)
Re:Ion drive (Score:2)
Is that g as in 9.8 ms^-2? Or is it the universal constant of gravitation? Either way I'd be interested if you could tell me how it relates to an ion drive in the middle of space? Thanks Henry
Re:Ion drive (Score:5, Informative)
Let me define a few things real quick
It=total Impulse=Thrust*Time [N-s]
F=Thrust [N]
t= time [s]
Mp=Propellant Mass [kg]
dMp/dt=Propllant mass flow rate [kg/s]
Wp=Propellant weight [N]
Isp=It/Wp=F*t/(Mp*g)
which if you solve for F in terms of Isp you get:
F=Isp*Mp*g/t
Then, you have Newton's law: F=dP/dt=d(mv)/dt which for a constat exit velocity you get:
F=Ve*dMp/dt
which for a constant mass flow can be written as:
F=Ve*Mp/t
Setting the two equations for thrust together you get:
F=Isp*Mp*g/t=Ve*Mp/t
which if you cancel out the Mp/t on both sides of the equation you get that:
Ve=Isp*g.
One of the real nice things about using Isp is that it's one of the few things that is the same in both EE and metric because it's units are seconds. For more info on this I recomend Chapter 2 from 'Rocket Propulsion Elements' by George Sutton and for a more advanced look at this stuff check out 'Space Propulsion Analysis and Design' By Humble, Henry and Larson. Both books can be purchased through Amazon or other large book sellers.
Re:Ion drive (Score:1)
Re:Ion drive (Score:2)
Re:Ion drive (Score:2)
Of course, since I'm trying mightily to focus on engines, I learned it as V-equivalent and not V_exit. (for those who dunno: V_eq=V_e if the pressure of the gas that's escaping your nozzle is at the same pressure as Whatever Surrounds Your Craft. Not actually possible in vacuum.)
Re:Ion drive (Score:2)
Yikes, typo. (Score:2)
Re:Ion drive (Score:5, Funny)
Re:Ion drive (Score:2)
Re:Ion drive (Score:2)
Ice? (Score:5, Informative)
Re:Ice? (Score:4, Informative)
http://nssdc.gsfc.nasa.gov/planetary/ice/ice_merc
Re:Ice? (Score:1)
How can the night be 1/2 of a day's duration? What am i missing here?
Re:Ice? (Score:2, Funny)
Re:Ice? (Score:4, Informative)
-calyxa
Bottom of the (gravity) well (Score:5, Interesting)
Sure there are lotsa other places to look too but this is a tidally-locked object not far from where many inner-system comets end up, ie the Sun. It'd be curiouser if Mercury hadn't intercepted a few comets over the eons and there weren't some traces of those collisions left on the benign parts of the planet.
Re:Bottom of the (gravity) well (Score:4, Informative)
This means that it does rotate relative to the sun, so there's no permanent "dark side".
(For comparison, the moon is tidal-locked 1:1 with Earth, so we never see the far side.)
Re:Bottom of the (gravity) well (Score:2)
Ha! Unless its helium you're looking for!
Oh, wait..Crap! [yarchive.net]
Re:Bottom of the (gravity) well (Score:1)
Permanent shadows = lower temperatures which could mean ice.
Similar studies have been done for other celestial bodies (including our Moon).
Is it hot or is it me? (Score:3, Funny)
Then in the case of Mercury, I guess it really is the heat, not the humidity that gets to you :P
Maybe interesting... (Score:1, Redundant)
---
Looks like crap to me (Score:5, Insightful)
This image beautifully illustrates the multilayered approach the team devised to fend off the excess heat while the spacecraft is near Mercury
Are we looking a the same picture?
This [astrobio.net] is not an informative image.
It could just as well be Fruit Fucker Prime [penny-arcade.com] with a tarp over it.
Impressive technology. Abysmal photography.
Re:Looks like crap to me (Score:2)
Re:Looks like crap to me (Score:2)
Re:Looks like crap to me (Score:2)
Send a rover! (Score:4, Interesting)
Mercury must have some interesting elements collected from solar winds.
A good landing site would be on the dark side obviously to avoid overheating.
However, if I remember correctly, Mercury also sports the coldest temps in the solar system due to its rapid evaporation.
Kind of like the cooling effect one gets when a wind blows on wet skin.
But I somehow doubt those rumors with it being so close to the sun.
So how about playing on the transitional areas of light and dark areas.
This planet was thought to be like our moon in that the same face points towards the Sun, leaving a perpetual dark and light side. However, it was shown to have a strange rotation of three rotations every two of its years.
What I would like to see from a rover is a video showing the sunsets and sunrises.
Its suppose to be really bizarre.
The sun rises and picks up speed as it grows in size! Then it pauses at the top and reverses the process.
If they did find ice water on the planet, do you think huddling some poor humans in a crater there would be beneficial or sacrificial?
Just some musings.
Re:Send a rover! (Score:3, Insightful)
The rover would have to move continuously to stay in the correct temperature zone. So you would need to know in advance that you could travel round a significant part of the circumference without encountering obstacles.
It would obviously have to stay in the dark because any level of sunshine would overheat it. So it would never see a sunrise or sunset. It would just crawl sadly around staying in the zone that current electronics and motors can handle (say -25 to 70C) until the batteries ran
Re:Send a rover! (Score:2, Informative)
Further, with such a slow procession, there would be no need to worry about getting caught in the sun. Mapping would take place with the current messanger anyway.
As for overheating, just give the thing 20 Kapton Umbrellas.
Here is a short movie I created in StaryNight Pro to give a good visualization of a sun rise and set:
spacecanada.org/mercuryrising.mov
Re:Send a rover! (Score:3, Informative)
Re:Send a rover! (Score:1)
It has time to reactivate the rover deal.
They should include the already proven Mars rover technology. Although, with little atmosphere its probably going to need different braking tactics.
Since the night and day sides both get exposure to the Sun over a the year, I would imagine there to be no difference in samples, but you never know.
http://sci.esa.int/science-e/www/object/in d ex.cfm? fobjectid=31273
A core sample would be intere
Re:Send a rover! (Score:3, Interesting)
Re:Send a rover! (Score:1)
You could bundle the rover seperately and then use its onboard cameras to monitor Bepi during the voyage.
Although you'd have to share the shielding or make another umbrella.
The information would be far far more valuable with a rover.
The landing should be no more difficult than the moon landing.
Hey, I just figured something.
Could you not deploy a big solar wind grabbing parasail to do the braking?
This would greatly save on propellants.
more musing.
Re:Send a rover! (Score:2)
Re:Send a rover! (Score:1)
Mercurian Year: about 90 Earth Days.
So its one hell of a long night. (about 2 Earth months)
Great for partys though!
Imagine the money Rave clubs would pull in.
Re:Send a rover! (Score:2)
Re:Send a rover! (Score:1)
Thats got to change the nature of things.
Hmmmm...
How about deploying a reflective blanket onto the surface or in orbit if you can keep it there?
Then we could bounce lasers off it and use it to keep a probe protected like a bug under the rug.
Re:Send a rover! (Score:3, Insightful)
Re:Better yet, don't send anything... (Score:2)
If we wait for that, we'll never learn anything about our universe except how imperfect humans are.
Re:Better yet, don't send anything... (Score:1)
A mission to Mercury can wait two or three hundred years. Mercury isn't going anywhere
The problems on Earth aren't going anywhere either. I'm a firm believer that spending more money on Space Exploration will eventually help solve earth problems, or give us an escape plan.
Re:Better yet, don't send anything... (Score:2)
This is another example of a space exploration project that should be shelved until the problems on Earth are dealt with.
....and the problems with earth are solvable entirely by engineers? Ah yes, nothing to do with cheap oil. or an industry dedicated to finding more of it. or your general suv loving suburbanites.
I HATE that attitude. (Score:4, Insightful)
Re:I HATE that attitude. (Score:2)
The problems of the Earth's people do get effectively dealt with. Plague, Smallpox, and polio, and soon malaria are no longer killing millions of people.
Famine has been solved by the 'Green Revolution' and the development of geneticially engineered food plants.
Corruption is dealt with by systematic analysis of money flows, binding legal structures, and a growing awareness of the community of its corrosive effects. The Mafia is a pale shadow of what it was fifty years ago in the USA.
Yup, and I can't mow my lawn until... (Score:2)
Yup, can't chew gum and walk at the same time either.
Re:Better yet, don't send anything... (Score:1)
Metalized Kapton Film (Score:5, Interesting)
Kapton [dupont.com] is a polyamide film duPont product that's been around for some 30 years . . .
I wonder if its the same metalized film used in some automobile window heat shields (or might that be metalized biaxially oriented nylon film)?
Re:Metalized Kapton Film (Score:3, Interesting)
And recently I've been using it in my cryogenic experiments. In the dilution fridge in my lab we can get to temperatures as low as 20 mK. Kapton tape is stable at these low temps, and provides a good way to ensure insulation between two conductors while still being 'removable'.
Re:Metalized Kapton Film (Score:1)
Are you trying to say that there is something wrong with us working so hard and being good consumers? What are you? A communist? Don't you see, it's all for the good of the markets?
If you don't work and buy all you can, the markets will get sick like a baby that's not fed and kept warm - you don't like babies getting sick, now do you?
So get ou
Mercury Mythology (Score:1)
Not Merchant. (Score:2)
Re:Not Merchant. (Score:1)
Messenger? (Score:1)
Good Lord, how stupid! (Score:3, Funny)
Sheesh.
ice? (Score:2)
Aren't they just getting too obsessed with finding ice and water? how about looking for something else?
Re:ice? (Score:2)
Re:ice? (Score:2)
I get your point though, where are the frozen alcohol deposits?!
rovers (Score:2)
A rover is an interesting idea, but it's pretty complicated to actually achive. Mercury is not rorationally locked to the Sun, so if you land something on the shade side, it'll rotate into sunlight within a month, or so.
The big difference between Mars and Mercury when it comes to rovers would be that a rover on Mars is facing towards Earth every 24 hours, or so. (One Mars day is just a little over 24 hours). But, the Mercury orbit and rotation period
Re:rovers (Score:1)
The whole point is to land send data and then make molten computer parts....short of interplanetary art.
Federal budget vetoed Messenger mission (Score:3, Informative)
Re:Neat (Score:1)
Re:Neat (Score:1)
I use Bill as a desktop but when I need to do any real work I log on to one of our many Linux systems and guess what...."Vision" (I think thats it's name) or something like that is what we use for X windows software and it's an SCO product.
So what I'm saying is simple.
When I need to do a detailed simulation on a Red Hat Linux system the results are presented to me through an SCO product on a Windows system.
What a world... What a world....
Re:Looking for water... (Score:5, Funny)
(Just proof that any dumb @$$ can get elected in America...ooooh, pretty shiney!)
Re:Looking for water... (Score:2, Informative)
Re:Looking for water... (Score:2)
Re:Looking for water... (Score:1)
Re:Looking for water... (Score:2)
Re:Looking for water... (Score:1)
It's no wonder that most of the big military tech that Reagan claimed credit for was actually initiated during Carter's time, nor that we had the most progressive alternative energy programs during that time. That was his field.
But yeah -- nice guys make poor presidents in this country. We really don't respect honesty, and that makes someone like Carter pretty ineffective in the political are
Re:Looking for water... (Score:1)
Re:Looking for water... (Score:2)
Hoover is the only OTHER president besides Bush to have a net job loss during his presidency. Think you're right about the engineers.
Re:Looking for water... (Score:1, Insightful)
Yup. And Clinton got elected twice!
I'm really surprised at the Slashdot crowd. Understandably some are upset at the decision to stop funding Hubble. Others are upset that Bush wants a moon shot before a Mars shot. Still others are quite upset about the lack of tech jobs. But I figured that any president that was for NASA spending would be supported here. Sure, Bush isn't the greatest president - he should have gotte
Re:Looking for water... (Score:2)
Re:Looking for water... (Score:2)
I hypothesize that the knee-jerk anti-Bush vitriol found on this site is produced largely by college students who haven't grown up enough to realize that being blindly against one party/candidate just leaves them open to abuse by the other party/candidate. They've also had so much anti-Bush rhetoric forced on them on campus that they haven't stopped to think that there are other valid positions.
Just my theory, though.