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Spacecraft Buzzes By Mercury
Riding with Robots writes "The robotic spacecraft MESSENGER is making its second fly-by of the first planet today, skimming just 200 kilometers above the surface. The fly-by will reveal portions of the planet that have never been seen before, but the main purpose of the maneuver is to prepare for an orbital insertion in 2011. The mission site offers extensive information, along with the first pictures that are already arriving on Earth, with many more expected in the coming hours and days."
oooooooo, raw!
Larry Niven's first published short story was titled "The Coldest Place" (collected in 3 Books of Known Space ), based on the idea that the regions of Mercury not hit by the sun would be the coldest place in the solar system. The story was infamous out of date by the time it hit print, as some studies of Mercury had shown that it never got that cold. Nonetheless, reading the story as a child awoke a certain interest of that planet which never gets as much attention as the sexier Mars or Venus or the gas giants. I look forward to following this mission.
The word buzz always makes me think of a dildo. Especially when a girl is like "hey, give me a buzz later".
In space, no-ine cabhear you Buzz.
The data returned by the craft seems to consist mostly of photos of a skinny guy with a moustache singing about champions and radios.
Slashdot Burying Stories About Slashdot Media Owned
I thought this kinda thing wasn't happening when I read the No Space Porn article?
which makes sense as they have no intentions to stop wrecking this planet. truth is though, it's not going to happen, as there's no where left to hide. we are all our own reward. we also have poor memories, & keep doing the same behaviors & expecting different results, one of the criteria for mental illness diagnosis. of course, it's not all our fault, as we are constantly being distracted/bushwhacked by man made foibles.
greed, fear & ego are unprecedented evile's primary weapons. those, along with deception & coercion, helps most of us remain (unwittingly?) dependent on its' life0cidal hired goons' agenda. most of yOUR dwindling resources are being squandered on the 'wars', & continuation of the billionerrors stock markup FraUD/pyramid schemes. nobody ever mentions the real long term costs of those debacles in both life & any notion of prosperity for us, or our children, not to mention the abuse of the consciences of those of us who still have one. see you on the other side of it. the lights are coming up all over now. conspiracy theorists are being vindicated. some might choose a tin umbrella to go with their hats. the fairytail is winding down now. let your conscience be yOUR guide. you can be more helpful than you might have imagined. there are still some choices. if they do not suit you, consider the likely results of continuing to follow the corepirate nazi hypenosys story LIEn, whereas anything of relevance is replaced almost instantly with pr ?firm? scriptdead mindphuking propaganda or 'celebrity' trivia 'foam'. meanwhile; don't forget to get a little more oxygen on yOUR brain, & look up in the sky from time to time, starting early in the day. there's lots going on up there.
http://news.google.com/?ncl=1216734813&hl=en&topic=n
http://www.nytimes.com/2007/12/31/opinion/31mon1.html?em&ex=1199336400&en=c4b5414371631707&ei=5087%0A
http://news.yahoo.com/s/ap/20080918/ap_on_re_us/tent_cities;_ylt=A0wNcyS6yNJIZBoBSxKs0NUE
http://www.nytimes.com/2008/05/29/world/29amnesty.html?hp
http://www.cnn.com/2008/US/06/02/nasa.global.warming.ap/index.html
http://www.cnn.com/2008/US/weather/06/05/severe.weather.ap/index.html
http://www.cnn.com/2008/US/weather/06/02/honore.preparedness/index.html
http://www.nytimes.com/2008/06/01/opinion/01dowd.html?em&ex=1212638400&en=744b7cebc86723e5&ei=5087%0A
http://www.cnn.com/2008/POLITICS/06/05/senate.iraq/index.html
http://www.nytimes.com/2008/06/17/washington/17contractor.html?hp
http://www.nytimes.com/2008/07/03/world/middleeast/03kurdistan.html?_r=1&hp&oref=slogin
http://biz.yahoo.com/ap/080708/cheney_climate.html
http://news.yahoo.com/s/politico/20080805/pl_politico/12308;_ylt=A0wNcxTPdJhILAYAVQms0NUE
http://www.cnn.com/2008/POLITICS/09/18/voting.problems/index.html
http://news.yahoo.com/s/nm/20080903/ts_nm/environment_arctic_dc;_ylt=A0wNcwhhcb5It3EBoy2s0NUE
(talk about cowardlly race fixing/bad theater/fiction?) http://money.cnn.com/2008/09/19/news/economy/sec_short_selling/index.htm?cnn=yes
http://www.nytimes.com/2008/10/04/opinion/04sat1.html?_r=1&oref=slogin
(the teaching of hate as a way of 'life' synonymous with failed dictatorships) http://news.yahoo.com/s/ap/20081004/ap_on_re_us/newspapers_islam_dvd;_ylt=A0wNcwWdfudITHkACAus0NUE
is it time to get real yet? A LOT of energy is being squandered in attempts to keep US in the dark. in the end (give or take a few 1000 years), the creators will prevail (world without end, etc...), as it has always been. the process of gaining yOUR release from the current hostage situation may not be what you might think it is. butt of course, most of US don't know, or care what a precarious/fatal situation we're in. for example; the insidious attempts by the felonious corepirate nazi execrable to block the suns' light, interfering with a requirement (sunlight) for us to stay healthy/alive. it's likely not good for yOUR health/memories 'else they'd be bragging about it? we're intending for the whoreabully decep
Anybody read the headline and get really excited for a second? Must be because I'm reading through Hitchhikers Guide to the Galaxy (again).
Sex. Drugs, and Unix.
argused 3y Eric
The sexier planets like Uranus
Or Urectum, whichever you prefer.
-=Bang Bang=-
Could someone please explain why according to the web site the orbit insertion is going to take another pass and another 3 years. Does it really take that long to slow the spacecraft down?
I'm no expert on orbital mechanics or anything, but it seems to be due to the massive change in velocity or "delta-v" (or call it vector). No way to carry enough fuel to effect that much speed change without using various orbits and the gravity of the planets around which they swing to change that vector enough that the amount of fuel on the craft can then make the smaller corrections required for orbit.
but, venus is hotter, lets do that next.
Because it is energetically tough to get to Mercury they are trying to get into with as little fuel expenditure as possible, to send as much payload as possible. Since there is no atmosphere, aerobraking is not possible, and thus they are using gravity assists to help reduce the orbital insertion delta-v to a manageable number. Each flyby speeds up the spacecraft a little, to better match Mercury's orbital velocity, and they decided on 3 of these to get the performance they wanted. There is a synodic period (the orbital beat period) between each such opportunity, so it takes a while to complete three flyby gravity assists.
The mission FAQ has more information on this.
sorry - "speeds up" should be "slows down," above.
The flybys and the ridiculously indirect route are not to speed up the craft, its actually to slow it down. Mercury is a very small planet, a little bigger than our moon, so the flybys are meant to slow down the craft enough so that it can be "caught" in the very low energy level orbit of Mercury.
Because it is energetically tough to get to Mercury they are trying to get into with as little fuel expenditure as possible, to send as much payload as possible. Since there is no atmosphere, aerobraking is not possible, and thus they are using gravity assists to help reduce the orbital insertion delta-v to a manageable number. Each flyby speeds up the spacecraft a little, to better match Mercury's orbital velocity, and they decided on 3 of these to get the performance they wanted. There is a synodic period (the orbital beat period) between each such opportunity, so it takes a while to complete three flyby gravity assists.
The mission FAQ has more information on this.
Ah, thanks! Very interesting.
It's so much like the Moon that it's quite boring to me.
Yeah, the core is slightly different and all but really, come on, it's just like our Moon in almost every way.
Moving around in space is all about changing your velocity. There are a number of ways to effect that change - gravitational slingshot, aerobraking, big sails, thrusters ... Each has advantages and disadvantages. For example, direct thrust may provide the most direct path to your objective, but the fuel requirement may be impractical. The mission designers have chosen a method of getting MESSENGER (about 1000kg of payload) to it's objective with enough fuel on-board to perform it's mission. Many variables have been considered - launch vehicle requirements, time to arrival, duration of mission, required consumables, etc. It's a horribly complex optimization.
The most efficient time/location to make orbital adjustments is apogee or perigee. If you enter into a highly eliptical orbit and wish to circularize at a much lower altitude using only a fractional-Newton thruster, yeah, it'll take a while. MESSENGER has a 650N main thruster, but only about 600kg of propellant. That equates to "not a lot" of thruster time. The main engine has a Specific Impulse (Isp) of 318 seconds. On Earth, you'd get about 318 seconds (5+ minutes) of operation. That gravitational element doesn't really apply out in space, so the available thrust-time will be longer. The NASA PDF indicates that the final orbital insertion burn will consume 30% of the propellant, and will last about 14 minutes. Extrapolating, that indicates that MESSENGER has about 42 minutes of propellant on board.
There's also a nice explanation of the orbital maneuvers on the JHUAPL website, and also a nice PDF showing the orbital insertion cost plots.
Note that MESSENGER used solar sailing to correct its trajectory for this flyby:
http://www.planetary.org/blog/article/00001674/
This is what we should be doing, instead of quibbling over small things like creationism and Paris Hilton. We should launch several satellites orbiting each planet and few satellites for some of the more interesting moons(Europa, io etc)
that means they gave linear velocity to Mercury. It's going faster. The whole space time continuum has now been altered. We're doomed!
I've always said English was my second language. Had Romeo and Juliet been written in C, I might have understood it.
When they eventually build a hotel on Mercury, I want an ice machine that works and doesn't keep running out of ice. So how big would such an ice machine have to be on Mercury? Would they have to charge $3 for a soda? I hate those tacky signs that say "No Filling Ice Chests."
If it was easy, they would have done it before now. We managed flybys of Merc 30 years ago, but those are much easier since you don't have to slow down.
The main engine has a Specific Impulse (Isp) of 318 seconds. [spaceref.com] On Earth, you'd get about 318 seconds (5+ minutes) of operation.
No. Specific impulse, despite being measured in seconds, has nothing to do with how long the rocket can fire. That obviously depends on how much propellant you carry.
Take another look at that Wikipedia article you linked on specific impulse.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Ok apparently the rest of the mods are sleeping on the job today. Reading TFA Your first assertion was correct. It's not about slowing down the thing needs to speed up in order to match mercury's orbital velocity of 47.9 km/s which is quite a bit faster than earth's measly 29.8 km/s:
Info on gravity assists for the MESSENGER mission.
There will actually be 6 total flybys (3 of mercury, 2 of venus, 1 of earth) during which the spacecraft will accelerate in order to decrease its orbital period from 365 days (that of earth) to 88 (that of mercury).
Well as another poster in the above thread pointed out, that's incorrect.
To be "caught", you'd want low relative velocity to Mercury, surely.
And just because you missed it, I'll repost oneTheory's link: http://messenger.jhuapl.edu/the_mission/gravity.html
Crap ... typing too fast ... not enough sleep ...
... a little over 47 minutes. At least that's consistent with the other derived number. Sorry about that, Chief.
Fthrust = Isp * (mass flow rate) * (gravity on Earth), which allows us to solve for the mass flow rate:
650N = 318s * MFR * 9.8m/s^2
MFR = 0.209 kg/s
With 600kg of propellant on board, you'd be able to fire the engine for 600kg / 0.209kg/s = 2871 seconds on the Earth's surface
With 600kg of propellant on board, you'd be able to fire the engine for 600kg / 0.209kg/s = 2871 seconds on the Earth's surface ... a little over 47 minutes.
True, though your calculation has nothing to do with Earth's surface. (When Isp is measured in seconds, they multiply by the gravity on Earth's surface just for fun.)
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....