Posted by
Hemos
on from the checking-things-out dept.
hubie writes "The NEAR spacecraft flew by the asteroid Eros at a closest approach of only 3 miles! Despite what the story says, that is much less than the altitude of a commuter aircraft. Stay tuned for some expected cool closeup shots."
Did anyone else laugh at the description of the "bird's eye view of the asteroid"? (South Saddle.) I had a fleeting image of some poor confused crow seeing this view as it flailed about with its useless wings and its last breath blew out into the vacuum.
This is extremely dangerous. With the low (almost nil) gravity on Eros, an alien lifeform can easily knock down our probe with nothing more than a well-aimed rock. I consider it a serious lapse of judgement in our elected officials to allow NASA to spend billions on such a risky endeavour.
I propose a Congressional panel to carefully scrutinize NASA's policies in regards to alien surface-to-air defenses, and whether the NEAR probe and others (Cassini! The Saturnians are watching!) are unjust provocations to our extra-terrestrial brethren.
I, for one, would like to welcome our new overlords, and would like to remind them that as a loyal Slashdot reader, I can be instrumental in rounding up the open-source zealots to toil in their salt mines.
The article is funny, but it raises a serious question. What kind of impression WOULD we give an alien inhabitant?
Put this in perspective. You're sitting out in your back yard, tossing back a Rolling Rock, when all of a sudden a grotesque looking alien object crashes into your pool. What would you think? How would you have any way of deciding whether the aliens were trying to destroy our civilization, or merely were sending out probes to investigate our odd little planet?
I wonder how much thought NASA actually has put into this sort of scenario. Do we need to take precautions to make sure that if, as unlikely as it may be, one of our spacecraft comes in contact with alien life, that it won't be interpreted as hostile or invasive? Hollywood has thrived on our fear of a hostile alien race invading Earth, while we at the same time run the (admittedly very, VERY small) of becoming the embodiment of an alien Hollywood staple.
Believe it or not there is a NASA team set aside for working out extra-terrestrial encounter scenarios. There was even a law passed outlawing any unauthorized contact with extra-terrestrial life or something like that.
Its funny, I read the law on the internet, and read about the team but now I don't have a clue as to where to start searching for it now. It was brought up in a Slashdot article many years ago, and with all the scrutiny Slashdot could muster at that time it actually turned out as legitimate.
Re:Only three miles!?!
by
ucblockhead
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· Score: 1
You're sitting out in your back yard, tossing back a Rolling Rock, when all of a sudden a grotesque looking alien object crashes into your pool.
I'd be thinking "Hot damn! I bet I can get at least 10 grand for that on eBay!"
This is extremely dangerous. With the low (almost nil) gravity on Eros, an alien lifeform can easily knock down our probe with nothing more than a well-aimed rock. I consider it a serious lapse of judgement in our elected officials to allow NASA to spend billions on such a risky endeavour.
How could any right-thinking red-blooded American like yourself just lie down and accept the threat from these alien sons of bitches? Surely you're not going to let this threaten democracy and our way of life? Show some true Yankee grit and tell NASA and the Air Force to put a nuke right up their ugly green ass:)
--
Any sufficiently advanced technology is indistinguishable from a rigged demo --Andy Finkel (J. Klass?)
Following closely in the orbit of Eros is another asteroid, named Phallus. Astronomers are unsure of the makeup of this asteroid, as it changes size and orientation periodically, growing larger and more vertical as it nears Eros.
Aren't all asteroids potato shaped? I surtenly have seen a lot of strage looking potatos in my time. "Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
--
- if you love something, set it free; if it doesn't come back, hunt it down and kill it
Okay, whoever named an/asteroid/ "Eros" is simply asking for dumb jokes. ----
-- ADVENTURERS! - ANTIHERO FOR HIRE - CARDMASTER CONFLICT
Actually 3 miles is high for a commuter
by
MackE
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· Score: 1
FWIW, three miles is a little over 15,000 feet. A typical puddle jumper will often be below 12,000ft. However, jets will almost always be above 25,000ft. Just to put it in perspective.
Re:Actually 3 miles is high for a commuter
by
shagrat
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· Score: 1
Depends on what you call a puddlejumper. Anything non pressurized that's carrying paying customers will need to stay below 10,500ft. Anything that's pressurized will probably go above 18,000ft so as to be in the flight levels - away from planes on VFR flight plans, and above at least some of the weather.
Re:Actually 3 miles is high for a commuter
by
Romeozulu
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· Score: 1
Not quite true. Some/most commuter planes do fly around 15,000 feet. They are pressurized, but they typically don't go much higher because there is nothing to be gain. The time/fuel to climb to 22,000 isn't worth it for the short hopes.
NEAR got a little too near!
by
AFCArchvile
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· Score: 1
The NEAR spacecraft flew by the asteroid Eros at a closest approach of only 3 miles!
Eek. 3 miles is really close for a fly-by. I wonder how much gravity it felt from that.
-- "Ancillary does not mean you get to rule the world." --U.S. Circuit Judge Harry Edwards, speaking to the FCC's lawyer
Actually, the article is right on that nit...
by
Tau+Zero
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· Score: 2
Commuter aircraft generally don't fly terribly high; they're often on relatively short hops and don't have any reason to fly at the kinds of altitudes typical of airliners. When it costs more time and maybe fuel to climb higher, or the upper levels are full of 757's and DC-10's and ACT won't clear you upwards, it makes no sense to even try. --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
Re:Actually, the article is right on that nit...
by
Alioth
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· Score: 2
Not really.
Commuter aircraft these days are typically things like ATR-42s and bigger. Unless the trip is really short, they usually fly at FL180 (18,000 ft) and above. Turbines are just thermodynamically a lot more efficient higher up. Virtually all commuter airlines are running turboprops. True - Redwing Airlines in Missouri, whose fleet consists of a single piston powered Piper Seneca (unpressurized) aren't going to be flying that high, but the majority of commuter airliners will be up that high so that their turbine engines at least get good fuel economy. The commuter airlines that operate the new regional jets will be up at FL250 (25,000') and higher, rubbing shoulders with their major airline brethren.
Also, ATC is there to serve us, and not the other way around. If you ask, ATC will normally give, especially once you're out of the busy terminal area. ATC in the United States are very good at working with the pilots to get them what they need.
Re:Actually, the article is right on that nit...
by
Tau+Zero
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· Score: 1
Interesting you should say that, because I was on a ~100-mile commuter hop (turboprop) a few years ago, and our cruising altitude was under 10,000 feet both ways. That may be "really short" to you, but it would surprise me if it's typical for the east coast. --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
it's about time nasa realized that it's alot more cost effective to come close to heavenly bodies than it is to crash into them. If I have to read one more "NASA to crash probe into _______" i'm going to scream! I mean, in the interest of science, crashing probes into distant moons or planets may be educational, but for the hundreds of millions of dollars spent on such missions, it seems the money would be better spent feeding homeless people, coming up with alternatives to petrochemicals to fuel our vehicles, buying everyone in the USA a puppy, or any of those things that would really make an impact in our society.
Hmm... looks like i forgot to put my soapbox tag in there....
--
"I hope I don't make a mistake and manage to remain a virgin." - Britney Spears
Actually, the NEAR mission has been one of the most successful recent NASA missions. It was built by the Johns Hopkins Applied Physics Lab (where I work!!!) at a cost $3.6 million below budget. Here's the JHUAPL press release.The NEAR mission is an example of the goals of NASA's latest rhetoric: "faster, better, cheaper". The official JHUAPL NEAR web site is here.
Well, so much for NASA's latest rhetoric. Later on today they are going to announce their proposed 2005 Mars Mission that is going to be a throwback to the old days. Supposidly they're giving up on cheap hardware and going back to the heavy duty gear. Ah well, it's kind of sad to see something like NEAR work so well and at the same time have 2 failures in the last year. Maybe NASA should be more careful in who they pick as their contractors - it sounds like you guys did a really good job.
Well, the last intentional crash of a probe was the Lunar Prospector, which was a wildly successful mission. NASA achieved all their goals including more accurate mapping of the moon than ever before, and once the mission was over the Prospector would have become so much space junk.
Except there's been a speculation about the moon that's lasted since we first began studying it in earnest. Does the moon have any water, even in crystaline form? They decided to sacrifice a sentimental piece of space junk to observe the impact and do a spectral analysis of the resulting shower of debris. Unfortunately, the results were negative. No water on the moon, at least in the region they hit.
What if they had? Well, water is a fundamental requirement for life, as well as one of the ingredients they use for propellant in outer space. So if they'd found ice on the moon it would have increased the chances of a lunar base by a large percentage, meaning we'd have a relatively convenient launching base for the exploration of the rest of the solar system. So don't knock it: there was a point to it.
As for the unintentional crashes, all I can say is that when you mix up your math you get all sorts of problems. NASA got too cocky and skimped on their error-checking in their haste to get projects out the door. They're paying for that, but I still support them. In times of peace, the kind of technological breakthroughs we've experience can at least in part be due to the push for space exploration. That air conditioning unit you can't live without? Space exploration. Minaturization of technology? Space exploration. Don't think that just because we're putting money into a project that doesn't provide immediate gratification (except for those astronomy buffs among us), we're not also researching a better way of life for everyone. If they figure out efficient waste recycling, it'll have benefits for the entire world.
-- There is no problem which cannot be resolved by the judicious use of firepower.
Holy cow! It's a rock! And it's in space! And it's got holes in it! And now we've got pictures!
And in a year, we're gonna smash our spacemobile into the rock! Yeah! Who's king of the world now, huh? King of the universe is more like it! Cha-cha-cha!
Ok, I'm done now.
--
"I am a cipher, a cipher, wrapped in an enigma, smothered in secret sauce" -Jimmy James
> Holy cow! It's a rock! And it's in space! And it's got holes in it! And now we've got pictures!
Believe me, if Eros had holes in it, as opposed to craters, I'd be phoning my broker with SELL orders, and then practicing up on my Wing Commander and other 3D space-combat game skills.
Cripes, didn't anybody here read Ender's Game? The buggers are out there, I tell you! They're out there!
do0d... that's the coolest thing... I can't wait until we can grab some close flybys of other such thing (like planets) with our own digital cameras from the window of our interstellar vehicle:-)
JDW
NEAR and first Mac in space
by
Racher
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· Score: 1
I don't know if I am %100 correct here, but back in the winter of '96 to '97. I had a copy of Popular Science that mentioned NASA new "Smaller, Faster, Cheaper" missions, in it there was obviously and article on the NEAR mission.
Well my entire thought was, that I remember reading that for part of the cheaper aspect on that mission for the main computer they used, an Apple PowerMac 9500/9600 or major parts from one.
This would totally go against that other story that talks about the first webserver and Macintosh computer in space. Sorry I couldn't find the recent link
...and I'm not sure we should trust this Kyle Sagan either.
I think the operative word is commuter. Yes, a 737 flies much higher than three miles (like six miles, if you consider that much higher). The commuter aircraft I ever flown in all flew at altitiudes between 5000 and 10000 feet (1-2 miles).
-- "On second thought, let's not go there. 'Tis a silly place."
--
-- "On second thought, let's not go there. Camelot is a silly place."
They said that 3 miles was about as high as a
commuter aircraft. Commuter aircraft are
the smaller passenger aircraft generally operated
in the US by regional airlines, and 3 miles is
reasonably close to how high they fly. They
were not talking about the large airliners
that generally fly roughly 6-8 miles high.
--
-- "Ever wonder why the SAME PEOPLE make up ALL the conspiracy theories?"
as a kid i was a huge space fan. Im always fascianted to look at pictures of stuff in space. I used to just flip endlessly through astronomy magazines and books just looking at the cool galaxies and stuff. what saddens me though, is how little interest society has on the space program these days. These people are literally risking life and limb in the name of bettering society. Many common day items are spun off from the space program. I feel like im the only one watching the lift offs of the space shuttle. I hope the populace regains its interest in the space program, it'ld seem like such a waste if they didnt
"sex on tv is bad, you might fall off..."
--
I lost my concept of community when my community lost all concept of me.
Look on the bright side
by
compwiz3688
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· Score: 1
That'll teach the Erosians not to mess with us. By the way... what did they do to us?
We should've told NASA that 3 miles is too far. We should be able to see the whites of the Erosians' eyes, as well as their surprised expressions. ---
The NEAR spacecraft, and the information that it is gathering, are probably one of the most worthwhile missions that NASA has ever had. The detailed look at Eros that it is providing will fill in a lot of details about our scientific knowledge of asteroids.
You can expect to see similiar missions to asteroids in the coming years. SpaceDev, a publicly owned company, is proposing NEAP, the Near Earth Asteroid Prospector. This probe, tentatively scheduled to launch in 2003, was originaly planned to visit the Near Earth Asteroid (NEA) Nereus. Recent discovery of hundreds of previously unknown NEA's may cause SpaceDev to delay the mission, and redirect the probe to some better target asteroid.
Additional missions? None scheduled yet. But you can bet they'll happen. The accessable resources of the asteroids have an estimated dollar value of about $100 Billion per person currently living on Earth. Someday soon, someone is going to dig into that Bonanza.
I agree! Now, why is it that the NASA homepage starts with links to speeches by NASA bureaucrats, and not to these amazing close-up photos of Eros? In fact, there are no links to NEAR anywhere on the homepage. In fact, there are no links to NEAR even on the "Hot Topics" page. Of course, you can still get directly to the bureaucrat speeches from there. Cause that's a pretty hot topic. Probably you'll all want to do that right away. Yeah. I'm thinkin' those speeches are gonna get purdy damn Slashdotted in jusasec here. Uh-huh.
Disappointing graphic in the article
by
Tau+Zero
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· Score: 1
It was interesting to see the "gravity map" of Eros, but it would have been far more enlightening to see a couple of other things:
A 3-view of the path of NEAR past Eros (which side did NEAR see?), and
A density map of Eros, showing which parts are more or less dense (and thus which are more likely to be rubble vs. solid).
Actual pics from the flyby would have been nice too. Why would the article talk about these things, but fail to show us any of them?:/ --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
Eros Photographed, Buggers Discovered!!!
by
Sir.Cracked
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· Score: 5
In a leak from the Defense Department, the first Photos of Eros revealed a race of insectoid beings that insider's are calling Buggers. Speculation is flying as to how to deal with the threat, with one idea of gathering all the most brilliant children up and putting them on a space station to train as generals. More at 11.
If you don't know what I'm talking about, read Ender's Game
-- Where are we going, and why am I in this handbasket?
pictures and project home page
by
pigpen_
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· Score: 2
The project home page has a lot of great photos and also daily updates on the project.
--
lukas
-- Zambozay! My brain must've been eatin' a sandwich!
Ummmm...commuter aircraft are passenger aircraft, too!
Many commuters fly at 18,000+ these days. They are pretty much all turbine powered, and turbines just operate more efficiently at higher altitude. Keeps them above all the VFR traffic too, and helps with weather avoidance.
Commuter airlines are now getting regional jets too, such as the Canadair regional jet and the Embraer offerings and the like. These cruise up with the big boys (FL250 and above), but they typically are doing the longer commuter airline routes.
Downloaded the movie!!!
by
GReaToaK_2000
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· Score: 2
DAMN!!!!
If that movie is to scale... That asteroid is pretty big.
I am thoroughly impressed and I like the NEAR team "spokes person" saying that the good news was they didn't hit it and there was no bad news. I think we are getting there. This is great.;)
1996 launch date means probably 1993 technology. I can live with that. I know that 8051 is the processor they used for the Patriot missle and that did a good job of hitting skuds. Therefore even if they used a 68K or 386/486 hardened for space that would be great... That might explain why they were able to avoid getting to NEAR the asteroid.;) It is probably something thing like 486 or 68K or ASIC which is good. This is only a guess considering the pentium was being hardened for space about 2.0 years ago.
I am excited, this is REALLY good news.;)
Good WORK!!!
Re:Downloaded the movie!!!
by
GReaToaK_2000
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· Score: 2
Flight Computer...
Honeywell MIL-STD-1750A 9MHz
512K RAM
256K EEPROM
16K PROM
Attitude Computer...:-)
Harris RTX2010 6MHz
64K RAM
64K EEPROM
2K PROM
For those that care. The specs for these processors are impressive.;)
NASA aimed at Mars and they had a bullseye twice. Wonder if they could also hit Eros:o)
First techie:"hey, were we using miles or meters?"
Second techie:" Um, i think we switched to that metric syst.."
-- This sig is intentionally left blank
NASA is underfunded!
by
Anonymous Coward
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· Score: 2
it's about time nasa realized that it's alot more cost effective to come close to heavenly bodies than it is to crash into them. If I have to read one more "NASA to crash probe into _______" i'm going to scream! I mean, in the interest of science, crashing probes into distant moons or planets may be educational, but for the hundreds of millions of dollars spent on such missions, it seems the money would be better spent feeding homeless people, coming up with alternatives to petrochemicals to fuel our vehicles, buying everyone in the USA a puppy, or any of those things that would really make an impact in our society.
I probably shouldn't even respond to a post this ignorant, but I can't resist.
First off, the only probes that have been "crashed" into anything (with the exception of probes which are at the end of their useful life) have been called "landers". Any crashes have been purely unintentional!;-)
Secondly, in those rare cases where a probe is sacrificed in a hostile environment (the upcoming drop of a Cassini module into Jupiter comes to mind), expending the probe is the only way to get any scientific data at all Believe me, the scientists involved would love to extend the useful lifetime of any probe if possible.
Regardless, it's hard to argue that NASA spends too much money - NASA's budget is tiny compared to what is spent on defense, for instance. The payoff from technologies and basic science sponsored by NASA is certainly far beyond anything we're likely to see from other government agencies. That said, I'd certainly like to see more private companies getting involved in space exploration.
Have a nice terrestrial rotation.
for those not in the know...
by
CiXeL
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· Score: 1
http://www.dictionary.com/cgi-bin/dict.pl?term=ero s
You mean in orbit?
by
Anonymous Coward
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· Score: 1
A turd in Earth orbit would liquify in the sun and solidify in the shade, eventually acquiring a sperical shape, it would have to be tracked lest a spac walking astronaut be killed by a liquid shit ball travelling at 3.5 miles per SECOND. That's lethal shit!
We interrupt your /. program...
by
Anonymous Coward
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· Score: 1
for a late breaking news:
After finding out that there are a race of insectoid beings living on Eros, the United States have immediately pumped billions of dollars into NASA for a quick mission. Initial reports are sketchy, but the President really liked the idea titled "Insects are for squashing". It utilizes our current technology of fly swatters and boots.
Good going Noam and the NEAR Team!
by
Tomin8tor
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· Score: 1
I know an instrument scientist who is working with some Infrared something-or-other-ometer aboard NEAR. He missed an important social get together in late February on account of the heavy data load coming in. They've been working like dogs for quiet a bit of time.
The NEAR team is racking up phenominal amounts of data about asteroids in general (and obviously this one in specific) that will undoubtedly take quite a while to analyze.
This project is one example of an effective, efficient, non-disasterous project that demonstrates that space can be done for cheap cost (relatively speaking) with the right management and mission concepts.
Now if only we can persuade NASA that the standard probe design (or even lander design) should not imitate the recreational lawn dart....
-- Pleasure in the job puts perfection in the work.
There was never a genius without a tincture of madness.
Aris
Re:Good going Noam and the NEAR Team!
by
Tackhead
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· Score: 3
> This project is one example of an effective, efficient, non-disasterous project that demonstrates that
space can be done for cheap cost [... ]
Agreed. NEAR is an awesome bit of work. Though the mission came extremely close to disaster. The reason we're reading about this in 2000 is because they damn near lost the spacecraft on first approach, and executed a miraculous recovery. It delayed the mission a year (waiting for the next orbit), but it didn't cost us much in terms of scientific return at all.
It's also a great demonstration of the fact that if you're in orbit around something - thinking of NEAR, Eros, and the Sun - whether you throw an object "up" or "down" makes no difference, it'll intersect your position next orbit.
That is, if you want to go "up" or "down" and you're in orbit, you thrust "forward" or "back". The EROS recovery was basically "screw it, don't waste fuel chasing the rock this year, because if we just relax, Newton will put us back on target for another encounter next year")
Actually, commuter aircraft do fly at 3mi
by
Atom+Tan
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· Score: 1
'hubie' is probably thinking of commercial jetliners (for example, 737s), which tend to cruise between 25,000 and 30,000 feet. Commuter aircraft, on the other hand, are generally turboprops with much lower service ceilings.
It is generally accepted that the Patriot missiles failed to have any significant success against Scuds. Some analysts have suggested that not one Scud was intercepted.
Look here for the official story, or here for another analysis.
But the really interesting report is the Postol/Lewis analysis, including detailed analysis of video evidence, is here
In the interests of balance, This is a response to it.
NEAR is in orbit around EROS. It has been for months. It's an astonishingly brilliant bit of orbital dynamics. What they have just done is to deduce the perigee gradually from ~= 120Km to bugger-all.
What's the big deal? We all know Han Solo landed his modified freighter, the Millenium Falcon, right inside a big asteroid, and it was much cooler looking than this one.
Plus he was being chased by hostile foes through a dangerous asteroid field, and escaped from the giant worm which was living in the asteroid, which is why you won't see anyone making a movie about the NEAR spacecraft.
NEAR has been in orbit around Eros for months. The orbit started at about 120Km out. They have gradually flown it closer and closer. The latest orbit is *very* close to the asteroid. Remember, this isn't a simple spherical object. The orbital dynamics are extremely complicated. Over the last few months, one thing they have been doing is building an accurate gravity map so that they can fly this close. I don't know how many "firsts" this mission has chalked up, but it's a lot.
Well you couldn't be more wrong about what processors are in this sucker!
There's actually 7 on-board, 6 of them are Harris RTX2010's (Harris is now Intersil). This processor can do 6 MIPS at 8MHz.. There is also one Honeywell 1750A that runs the flight program. (2.5 MIPS - The military hybrid of this chip also runs Linux ;;.)
I quote from the above.PDF: "All processors are Harris RTX2010's except the G&C subsystem Flight Computer which is a Honeywell 1750A."
Nice little satellite for early 90's.
-- I'm a 2000 man.
Re:on-board processors
by
GReaToaK_2000
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· Score: 1
Agreed.:) I already figured that out.
Look at the specs on the memory they included in the satellite. I included it in my correction of myself.
Well you couldn't be more wrong about what processors are in this sucker!
There's actually 7 on-board, 6 of them are Harris
RTX2010's (Harris is now Intersil). This processor can do 6 MIPS at 8MHz..
There is also one Honeywell
1750A that runs the flight program. (2.5 MIPS - The military hybrid of this
chip also runs Linux.)
I quote from the above.PDF: "All processors are Harris RTX2010's except the G&C subsystem Flight
Computer which is a Honeywell 1750A."
There are actually 2 identical 1750As on NEAR, both running the Guidance and Control code (in Ada).
There are rad-hard versions of Power PC processors that could fly in space. However, these are emphatically not Macs. JPL flies and rad-hard RS6000, I believe, which has common lineage with the Power PC.
--
Helium balloons want to be free.
GLOBE
by
Anonymous Coward
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· Score: 1
Does anyone have a 3d model of this asteriod? or others? I would understand it better if I could roll a globe of it around. Quicktime VR, VRML, or something. Wouldn't that be nifty??
What processors NEAR runs off of..
by
eples
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· Score: 3
Well you couldn't be more wrong about what processors are in this sucker!
There's actually 7 on-board, 6 of them are Harris
RTX2010's (Harris is now Intersil). This processor can do 6 MIPS at 8MHz..
There is also one Honeywell
1750A that runs the flight program. (2.5 MIPS - The military hybrid of this
chip also runs Linux ;.)
I quote from the above.PDF: "All processors are Harris RTX2010's except the G&C subsystem Flight
Computer which is a Honeywell 1750A."
It's not much less than a commuter aircraft, unless you commute accross the Atlantic. Short-distance aircraft don't go to 10km altitude like long-distance aircraft, because for short distances it's not worth it (the cost of climbing to that altitude is more than the gain you get from flying in thin air/strong wind). 5 km is about right for a commuter.
If you look at frames 43, 44 & 45 of this orbital animation of eros you can clearly see a huge boo-scary tortured-looking face on the surface!
I know it's a meritless thing to point out and has no real scientific significance (like the infamous "face on Mars"), but considering that:
It's named after the Greek god of love (dual entendre, anyone?)
It's shaped like a loaf
It's almost Hallowe'en
...I found it pretty funny on three separate levels, which could lead to some great Onion-esque headlines...
Following Probe, Lusty Anthropomorphic Asteroid Hurtles Toward Uranus
Mister Hanky's Mothership Arrives
Approaching Space Demon "Eros" Denies Connection to Ancient Ones, Intention to Destroy Earth
-- Snickersnee3: Build your own 3-watt Luxeon Star headlamp from scratch
Re:Can objects orbit at really low altitudes? cm?
by
hardburn
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· Score: 1
Quick crash course in orbital flight:
Every second, Earth (and any other object, for that matter) pulls a smaller object tward it at a set ammount acceleration (on Earth, its 9.81 m/s/s). So, if you travel at 30,000 km/s (just the throw out a number) you will still fall twards the Earth at 9.81 m/s/s. However, since the Earth is round, you will go out 30,000 km every second, while falling 9.81 m. Repeat this over and over and you will form an orbit around the planet. Objects in orbit are quite literaly falling around the Earth.
If you want to go higher in orbit, you mearly go faster and you will automaticly be pushed there. To go lower, just go slower. This is why there is a set speed and height for objects in geosyncronis orbit (which is when you are hovering over a specific point on the planet's surface).
This shows that there is a practical limit to just how slow you can go around the Earth, or else gravity won't care how fast you're going, you're going to hit that mountian!:)
So, the answer is, yes, you could, if gravity were low enough and your craft manuverable enough.
I hope this was clear. It helps if you have a few diagrams to show, but I don't have the time to make a few and give you the links to them, sorry.
------
-- Not a typewriter
Re:Can objects orbit at really low altitudes? cm?
by
ToddN
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· Score: 1
They most certainly can, and IIRC the final phase of this mission will be to allow the vehicle to graze the surface and dig a bit of a trench. Mind you the orbital speed at such a low gravity approximates walking speed.
You could actually launch a rock into orbit around Eros by throwing it. If it were spherical that would be kind of fun, pitch it, then watch it slowly come around the horizon from behind you.
Re:Can objects orbit at really low altitudes? cm?
by
jonnythan
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· Score: 1
Er.....faster = lower orbit, because gravity is stronger. To orbit cm's above a planet would require much higher velocities than miles above a planet. Give a rock a strong enough throw at the right angle, and you can get it to orbit a sphere at an arbitrary height. Make the planet slightly denser and hence smaller, and the orbiting object won't know the difference. A point-mass can have an object orbiting at any distance above it...just expand the volume and keep the mass to get it as close to the orbiting object as you wish.
Go back to physics class or take some calculus and rethink your "go faster and you will automatically be pushed [farther out]" idea.
Do the NEAR spacecraft have a color camera ? I only find b/w photos of Eros.
How is it possible that in year 2000 it has no color camera !? The old 70's Viking Mars lander had one!
-- MOD THE CHILD UP!
Re:Can objects orbit at really low altitudes? cm?
by
Mad+Hughagi
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· Score: 2
Actually...
Both of your descriptions are accurate, it is just that you are describing different things. The parent post is talking about an object that is allready in a stable orbit. In that case if you increase the tangential component of your velocity you would move into a higher orbit. What you are describing is the tangential velocity required to maintain a stable orbit, which is also true.
Just because something doesn't make sense at first doesn't mean that it is wrong, maybe you just haven't wrapped your head around it properly.
What is utterly amazing is that Eros has loose rocks lying on its surface, with their size ranging down to below the camera resolution.
How did they come to be there given the level of Eros's gravity? If a meteor hit Eros, the debris from the impact would fly off far too fast to be recaptured by Eros, yet if the rocks aren't impact debris, where did they come from?
He's out there somewhere, travelling in a faster-than-light spacecraft..
But that can't be right...
by
Anne+Marie
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· Score: 1
According to Plato, Eros is the striving of mankind to the pure, the good, the beautiful. Plato said nothing about photographic artifacts in satellite fly-bys of minor planets. Anyway, back to work. Plato said he left Atlantis lying around here somewhere....
The law in question was repealed in 1991 without any fanfare. You're now free to touch aliens all you want, as long as you make sure they aren't same-sex or under-age aliens.
"And here we see that, yes, surprisingly, this is just a big rock. Over here we have some holes, and here, just behind that small rock, is a big rock. And there's another rock. And another one. Lots of rocks people. Great stuff."
The only fool bigger than the person who knows it all, is the person who argues with him.
-- I do not respond to cowards. Especially anonymous ones.
Eros Surface(s) near skirts
by
Anonymous Coward
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· Score: 1
When I first read the title of this story, I didn't think it had anything to do with space exploration... I thought it was some kind of government funded study of geeks.
Dude... 30,000 km/sec is about 30% of the speef of light. You wouldn't be in orbit, you'd be heading off on an almost-linear escape trajectory (and fried by all the solar wind protons you'd be passing through, which would look like several-hundred-MeV cosmic rays to you). --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
Mind you the orbital speed at such a low gravity approximates walking speed.
Not according to this NASA page; the escape velocity is around 22 MPH (from where on the asteroid, they don't say). Divide by sqrt(2) to get the surface-skimming orbital velocity for a spherical body (yeah, right) and it comes out to about 15 MPH. Definitely a fast run, not a walk. I have not run the numbers to see where on Eros that escape velocity figure would apply, but if it's at either of the ends the rotational velocity (33 km * 3.14 / 5.27 hours = 19.7 km/hr = 12.2 MPH) would give you well over half of it.
If you want to try working out the orbital speeds yourself, you'll need the gravitational constant G (6.67 * 10^-11 N m^2/kg^2) plus the mass and dimensional data on the NASA page linked above.
I find it interesting that you could land on Eros with the equivalent of a big pogo stick, and launch yourself to escape velocity the same way. --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
Do a little Google searching, and see what it gets ya. I found this (cited above), from which I quote:
A 100-pound (45-kilogram) object on Earth would weigh about an ounce on Eros
... from which you can deduce that the acceleration would be about 1/1600 G at the surface, and somewhat less at the 5 km fly-by distance (depending exactly where the fly-by occurred; a pass near the middle would have a lesser relative reduction in gravity than a pass over one end). --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
in those rare cases where a probe is sacrificed in a hostile environment (the upcoming drop of a Cassini module into Jupiter comes to mind)
You mean the Huygens probe into Titan, which is a moon of Saturn. Galileo dropped a probe into Jupiter, but that was several years ago. --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
Would you settle for "close pass"?
by
Tau+Zero
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· Score: 1
It was a very close pass, and according to the BBC the orbit has since been raised to 200 km. That counts as a fly-by in my book; they're coming back, but they're not in orbit at 5 km over the thing.
This BBC article has the picture I was hoping for. Looks smoother than the Moon to me, lots of dust with a few rocks and no rims on the craters. It also contains this utterly hilarious typo:
Near has now moved back into a safer orbit some 200 km (124 miles) above the
Earth.
I guess Eros is even more of a "near-earth asteroid" than anyone thought! --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
NO STARS IN THE BACKGROUND? Of COURSE not.
by
Tau+Zero
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· Score: 1
The stars are washed out by the glare of the asteroid, which is in full sun. You can't see stars right next to the moon either, and your eye has a lot better dynamic range than either cameras or film.
People used the same argument to claim that the footage from the Apollo missions was faked. The argument is just as bogus today as it was 30 years ago. --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
"close pass" is an understatement...
by
m00ng00
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· Score: 1
Keep in mind that the orbital corrections are done with a significant time delay -- this is a situation where the speed of light *matters*:-).
Getting that close to Eros successfully is nothing short of remarkable IMO.
There was an article in Scientific American years ago about the mods made to the Voyager probes in flight (wish I could remember the specific issue), and it really gives you a feeling of wonder about the fact that we monkeys can do this stuff at all...
-- "Each day, each moment brings its change," Ghanima said. "One learns by recognizing the moments."
Re:"close pass" is an understatement...
by
Tau+Zero
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· Score: 1
Keep in mind that the orbital corrections are done with a significant time delay -- this is a situation where the speed of light *matters*
They could probably take a few pointers from the Deep Space One team and DS-1's auto-nav software. Heck, NEAR has a laser rangefinder; it should be relatively simple to have it fly a path and just abort to a higher orbit if something goes wrong. --
-- Time is Nature's way of keeping everything from happening at once... the bitch.
You are right about being able to orbit at any altitude, of course, friction of the atmosphere would become significant at lower altitudes.
You were only partially right when you said that the earth's gravity pulls at 9.8 m/(s^2), actually, according to Universal Gravity, two bodies will attract eachother with a force governed by the following equation:
F=(G M m)/(r^2)
Where F is the force of attraction, G is the gravitational constant (about 6.67*10^-11 m^3/(kg/s^2)), M and m are the masses, and r is the distance between the the two bodies' centers of gravity.
That is all well and good, but it dosen't tell us what the force of attraction for the earth is. To discover that, we have to use another equation, Newton's second law:
F= m a
Where F is force, m is mass, and a is (you gussed it) acceleration.
We can set F equal to F and yeald:
m a = (G M m) / r^2
We can cancel out the two small 'm's to get:
a = (G M) / r^2
We need a 'r' and a 'M', so I will now stipulate that the radius of the earth is about 6.38*10^6 m and that the mass of the earth is 5.98*10^24 kg. An abitious slashdoter could most likely find much more accurate figures, but these will fit our purposes. Consequently, we can find the acceleration due to gravity with:
a = (6.67*10^-11 * 5.98*10^24) / ((6.38*10^6)^2)
a = 9.799 m/(s^2)
I hope you can see that 'a' would be significantly less were an object higher (say, 500km) from the surface of the earth, as 'r' would increase:
a = (6.67*10^-11 * 5.98*10^24) / ((6.38*10^6 + 500*1000)^2)
a = 8.427 m/(s^2)
Back to the original question: How fast must an object to travel to orbit the earth at the surface? To answer that, we have to call apon yet another equation, that of centripical acceleration in circular motion:
a = (v^2) / r
We know that the centripical acceleration is the acceleration due to gravity, which we found to be 9.799 m/(s^2) at the surface of the earth, and we know 'r' to be the radius of the earth, so to find 'v' (velocity) we could have:
v = sqrt( a r )
v = sqrt( 9.799 * 6.38*10^6)
v = 7906.81 m/s
v = 7.907 km/s (*)
As you can see, this is significantly less than your figure of 30,000 km/s!
(*) Us Americans, who's brains have been destroyed by the English System, would get more sense out of 17,687 mi/hr.
--
Jordan Bettis
``Wherever you go, there's another stupid sigfile quote.''
I got out of physics class last school year, dumped much of my knowledge over the summer, and by now I can remember lots of concepts but few equations. (Thats why my 30,000 km/s was so far off!)
------
-- Not a typewriter
Consider it a rehearsal for a Comet rendevous
by
LtlPhysics
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· Score: 1
NASA already has plans for a deep space probe to sample the tail of a comet, a simple flythrough that has the potential of capturing some organic compounds. To match speed and orbit a comet all of the way around the sun is big science, whether or not the probe or comet survive. Organic compounds and water ice would rewrite the origins of life. We have to check it out.
Slashdot Mirror
That's pretty close.
Did anyone read about the Plutino rock they found between Neptune and Pluto? I love space.
--------------------
http://nssdc.gsfc.nasa.gov/planetary/mission/near/ near_eros.html
It's got some pictures up from today.
I propose a Congressional panel to carefully scrutinize NASA's policies in regards to alien surface-to-air defenses, and whether the NEAR probe and others (Cassini! The Saturnians are watching!) are unjust provocations to our extra-terrestrial brethren.
I, for one, would like to welcome our new overlords, and would like to remind them that as a loyal Slashdot reader, I can be instrumental in rounding up the open-source zealots to toil in their salt mines.
Any ideas to what shape an asteroid named "Eros" would be?
- I don't care if they globalize against free speech. All my best free thoughts are done in my head.
Okay, whoever named an /asteroid/ "Eros" is simply asking for dumb jokes.
----
ADVENTURERS! - ANTIHERO FOR HIRE - CARDMASTER CONFLICT
FWIW, three miles is a little over 15,000 feet. A typical puddle jumper will often be below 12,000ft. However, jets will almost always be above 25,000ft. Just to put it in perspective.
Eek. 3 miles is really close for a fly-by. I wonder how much gravity it felt from that.
"Ancillary does not mean you get to rule the world." --U.S. Circuit Judge Harry Edwards, speaking to the FCC's lawyer
Commuter aircraft generally don't fly terribly high; they're often on relatively short hops and don't have any reason to fly at the kinds of altitudes typical of airliners. When it costs more time and maybe fuel to climb higher, or the upper levels are full of 757's and DC-10's and ACT won't clear you upwards, it makes no sense to even try.
--
Time is Nature's way of keeping everything from happening at once... the bitch.
images here.
it's about time nasa realized that it's alot more cost effective to come close to heavenly bodies than it is to crash into them. If I have to read one more "NASA to crash probe into _______" i'm going to scream! I mean, in the interest of science, crashing probes into distant moons or planets may be educational, but for the hundreds of millions of dollars spent on such missions, it seems the money would be better spent feeding homeless people, coming up with alternatives to petrochemicals to fuel our vehicles, buying everyone in the USA a puppy, or any of those things that would really make an impact in our society.
Hmm... looks like i forgot to put my soapbox tag in there....
"I hope I don't make a mistake and manage to remain a virgin." - Britney Spears
Here's a number of pictures of it:
http://nssdc.gs fc. nasa.gov/planetary/mission/near/near_eros.html
Enjoy =)
---
do0d... that's the coolest thing... I can't wait until we can grab some close flybys of other such thing (like planets) with our own digital cameras from the window of our interstellar vehicle :-)
JDW
I don't know if I am %100 correct here, but back in the winter of '96 to '97. I had a copy of Popular Science that mentioned NASA new "Smaller, Faster, Cheaper" missions, in it there was obviously and article on the NEAR mission.
...and I'm not sure we should trust this Kyle Sagan either.
Well my entire thought was, that I remember reading that for part of the cheaper aspect on that mission for the main computer they used, an Apple PowerMac 9500/9600 or major parts from one.
This would totally go against that other story that talks about the first webserver and Macintosh computer in space.
Sorry I couldn't find the recent link
-- "On second thought, let's not go there. 'Tis a silly place."
-- "On second thought, let's not go there. Camelot is a silly place."
They said that 3 miles was about as high as a commuter aircraft. Commuter aircraft are the smaller passenger aircraft generally operated in the US by regional airlines, and 3 miles is reasonably close to how high they fly. They were not talking about the large airliners that generally fly roughly 6-8 miles high.
-- "Ever wonder why the SAME PEOPLE make up ALL the conspiracy theories?"
The altitude at which you look down out the airplane window and it looks like SimCity.
as a kid i was a huge space fan. Im always fascianted to look at pictures of stuff in space. I used to just flip endlessly through astronomy magazines and books just looking at the cool galaxies and stuff. what saddens me though, is how little interest society has on the space program these days. These people are literally risking life and limb in the name of bettering society. Many common day items are spun off from the space program. I feel like im the only one watching the lift offs of the space shuttle. I hope the populace regains its interest in the space program, it'ld seem like such a waste if they didnt
"sex on tv is bad, you might fall off..."
I lost my concept of community when my community lost all concept of me.
That'll teach the Erosians not to mess with us. By the way... what did they do to us?
We should've told NASA that 3 miles is too far. We should be able to see the whites of the Erosians' eyes, as well as their surprised expressions.
---
Here is the recent story I remember.
/.?
...and I'm not sure we should trust this Kyle Sagan either.
Wasn't it on
The NEAR spacecraft, and the information that it is gathering, are probably one of the most worthwhile missions that NASA has ever had. The detailed look at Eros that it is providing will fill in a lot of details about our scientific knowledge of asteroids.
You can expect to see similiar missions to asteroids in the coming years. SpaceDev, a publicly owned company, is proposing NEAP, the Near Earth Asteroid Prospector. This probe, tentatively scheduled to launch in 2003, was originaly planned to visit the Near Earth Asteroid (NEA) Nereus. Recent discovery of hundreds of previously unknown NEA's may cause SpaceDev to delay the mission, and redirect the probe to some better target asteroid.
Additional missions? None scheduled yet. But you can bet they'll happen. The accessable resources of the asteroids have an estimated dollar value of about $100 Billion per person currently living on Earth. Someday soon, someone is going to dig into that Bonanza.
- A 3-view of the path of NEAR past Eros (which side did NEAR see?), and
- A density map of Eros, showing which parts are more or less dense (and thus which are more likely to be rubble vs. solid).
Actual pics from the flyby would have been nice too. Why would the article talk about these things, but fail to show us any of them?--
Time is Nature's way of keeping everything from happening at once... the bitch.
In a leak from the Defense Department, the first Photos of Eros revealed a race of insectoid beings that insider's are calling Buggers. Speculation is flying as to how to deal with the threat, with one idea of gathering all the most brilliant children up and putting them on a space station to train as generals. More at 11.
If you don't know what I'm talking about, read Ender's Game
Where are we going, and why am I in this handbasket?
The project home page has a lot of great photos and also daily updates on the project.
--
lukas
Zambozay! My brain must've been eatin' a sandwich!
Tech #1: Dude! Watch where you're going with that thing! You're gonna hit the big floating rock!
Tech #2: Nah. We'll miss it by a mile. Three at least. Quit back-terminal driving ya pansy.
Hey if they're going to call it Eros...
BlackNova Traders
I think the author is confusing 'commuter aircraft' and 'passenger aircraft'. Passenger jets operate around 30 to 35,000 feet.
Just can't abide by misinformation. *grin*
-Greg
your pain, i feel it.
If that movie is to scale... That asteroid is pretty big.
I am thoroughly impressed and I like the NEAR team "spokes person" saying that the good news was they didn't hit it and there was no bad news. I think we are getting there. This is great. ;)
1996 launch date means probably 1993 technology. I can live with that. I know that 8051 is the processor they used for the Patriot missle and that did a good job of hitting skuds. Therefore even if they used a 68K or 386/486 hardened for space that would be great... That might explain why they were able to avoid getting to NEAR the asteroid. ;) It is probably something thing like 486 or 68K or ASIC which is good. This is only a guess considering the pentium was being hardened for space about 2.0 years ago.
I am excited, this is REALLY good news. ;)
Good WORK!!!
So how close do commuter aircraft get to this asteriod?
Nasa's Astronomical Picture Of The Day has some cool information and a picture (a map) of it: here
Wonder if they could also hit Eros
First techie:"hey, were we using miles or meters?"
Second techie:" Um, i think we switched to that metric syst.."
This sig is intentionally left blank
I probably shouldn't even respond to a post this ignorant, but I can't resist.
First off, the only probes that have been "crashed" into anything (with the exception of probes which are at the end of their useful life) have been called "landers". Any crashes have been purely unintentional! ;-)
Secondly, in those rare cases where a probe is sacrificed in a hostile environment (the upcoming drop of a Cassini module into Jupiter comes to mind), expending the probe is the only way to get any scientific data at all Believe me, the scientists involved would love to extend the useful lifetime of any probe if possible.
Regardless, it's hard to argue that NASA spends too much money - NASA's budget is tiny compared to what is spent on defense, for instance. The payoff from technologies and basic science sponsored by NASA is certainly far beyond anything we're likely to see from other government agencies. That said, I'd certainly like to see more private companies getting involved in space exploration.
Have a nice terrestrial rotation.
http://www.dictionary.com/cgi-bin/dict.pl?term=ero s
http://www.livejournal.com/users/cixel
A turd in Earth orbit would liquify in the sun and solidify in the shade, eventually acquiring a sperical shape, it would have to be tracked lest a spac walking astronaut be killed by a liquid shit ball travelling at 3.5 miles per SECOND. That's lethal shit!
for a late breaking news:
After finding out that there are a race of insectoid beings living on Eros, the United States have immediately pumped billions of dollars into NASA for a quick mission. Initial reports are sketchy, but the President really liked the idea titled "Insects are for squashing". It utilizes our current technology of fly swatters and boots.
I know an instrument scientist who is working with some Infrared something-or-other-ometer aboard NEAR. He missed an important social get together in late February on account of the heavy data load coming in. They've been working like dogs for quiet a bit of time.
The NEAR team is racking up phenominal amounts of data about asteroids in general (and obviously this one in specific) that will undoubtedly take quite a while to analyze.
This project is one example of an effective, efficient, non-disasterous project that demonstrates that space can be done for cheap cost (relatively speaking) with the right management and mission concepts.
Now if only we can persuade NASA that the standard probe design (or even lander design) should not imitate the recreational lawn dart....
Pleasure in the job puts perfection in the work.
There was never a genius without a tincture of madness.
Aris
'hubie' is probably thinking of commercial jetliners (for example, 737s), which tend to cruise between 25,000 and 30,000 feet. Commuter aircraft, on the other hand, are generally turboprops with much lower service ceilings.
Look here for the official story, or here for another analysis.
But the really interesting report is the Postol/Lewis analysis, including detailed analysis of video evidence, is here
In the interests of balance, This is a response to it.
NEAR is in orbit around EROS. It has been for months. It's an astonishingly brilliant bit of orbital dynamics. What they have just done is to deduce the perigee gradually from ~= 120Km to bugger-all.
What's the big deal? We all know Han Solo landed his modified freighter, the Millenium Falcon, right inside a big asteroid, and it was much cooler looking than this one.
Plus he was being chased by hostile foes through a dangerous asteroid field, and escaped from the giant worm which was living in the asteroid, which is why you won't see anyone making a movie about the NEAR spacecraft.
NEAR has been in orbit around Eros for months. The orbit started at about 120Km out. They have gradually flown it closer and closer. The latest orbit is *very* close to the asteroid. Remember, this isn't a simple spherical object. The orbital dynamics are extremely complicated. Over the last few months, one thing they have been doing is building an accurate gravity map so that they can fly this close. I don't know how many "firsts" this mission has chalked up, but it's a lot.
Nice one NASA.
Well you couldn't be more wrong about what processors are in this sucker!
There's actually 7 on-board, 6 of them are Harris RTX2010's (Harris is now Intersil). This processor can do 6 MIPS at 8MHz.. There is also one Honeywell 1750A that runs the flight program. (2.5 MIPS - The military hybrid of this chip also runs Linux ; ;.)
I quote from the above
"All processors are Harris RTX2010's except the G&C subsystem Flight Computer which is a Honeywell 1750A." Nice little satellite for early 90's.
I'm a 2000 man.
Well you couldn't be more wrong about what processors are in this sucker!
There's actually 7 on-board, 6 of them are Harris RTX2010's (Harris is now Intersil). This processor can do 6 MIPS at 8MHz.. There is also one Honeywell 1750A that runs the flight program. (2.5 MIPS - The military hybrid of this chip also runs Linux .)
I quote from the above
"All processors are Harris RTX2010's except the G&C subsystem Flight Computer which is a Honeywell 1750A."
Nice little satellite for early 90's.
I'm a 2000 man.
Does anyone have a 3d model of this asteriod? or others? I would understand it better if I could roll a globe of it around. Quicktime VR, VRML, or something. Wouldn't that be nifty??
Well you couldn't be more wrong about what processors are in this sucker!
There's actually 7 on-board, 6 of them are Harris RTX2010's (Harris is now Intersil). This processor can do 6 MIPS at 8MHz.. There is also one Honeywell 1750A that runs the flight program. (2.5 MIPS - The military hybrid of this chip also runs Linux ; .)
I quote from the above
"All processors are Harris RTX2010's except the G&C subsystem Flight Computer which is a Honeywell 1750A."
Nice little satellite for early 90's.
I'm a 2000 man.
It's not much less than a commuter aircraft, unless you commute accross the Atlantic. Short-distance aircraft don't go to 10km altitude like long-distance aircraft, because for short distances it's not worth it (the cost of climbing to that altitude is more than the gain you get from flying in thin air/strong wind). 5 km is about right for a commuter.
If you look at frames 43, 44 & 45 of this orbital animation of eros you can clearly see a huge boo-scary tortured-looking face on the surface! I know it's a meritless thing to point out and has no real scientific significance (like the infamous "face on Mars"), but considering that:
- Following Probe, Lusty Anthropomorphic Asteroid Hurtles Toward Uranus
- Mister Hanky's Mothership Arrives
- Approaching Space Demon "Eros" Denies Connection to Ancient Ones, Intention to Destroy Earth
Just look at it already, you'll see what I mean: http://n ssd c.gsfc.nasa.gov/planetary/image/near_20000919_larSnickersnee3: Build your own 3-watt Luxeon Star headlamp from scratch
Quick crash course in orbital flight:
Every second, Earth (and any other object, for that matter) pulls a smaller object tward it at a set ammount acceleration (on Earth, its 9.81 m/s/s). So, if you travel at 30,000 km/s (just the throw out a number) you will still fall twards the Earth at 9.81 m/s/s. However, since the Earth is round, you will go out 30,000 km every second, while falling 9.81 m. Repeat this over and over and you will form an orbit around the planet. Objects in orbit are quite literaly falling around the Earth.
If you want to go higher in orbit, you mearly go faster and you will automaticly be pushed there. To go lower, just go slower. This is why there is a set speed and height for objects in geosyncronis orbit (which is when you are hovering over a specific point on the planet's surface).
This shows that there is a practical limit to just how slow you can go around the Earth, or else gravity won't care how fast you're going, you're going to hit that mountian! :)
So, the answer is, yes, you could, if gravity were low enough and your craft manuverable enough.
I hope this was clear. It helps if you have a few diagrams to show, but I don't have the time to make a few and give you the links to them, sorry.
------
Not a typewriter
You could actually launch a rock into orbit around Eros by throwing it. If it were spherical that would be kind of fun, pitch it, then watch it slowly come around the horizon from behind you.
Er.....faster = lower orbit, because gravity is stronger. To orbit cm's above a planet would require much higher velocities than miles above a planet. Give a rock a strong enough throw at the right angle, and you can get it to orbit a sphere at an arbitrary height. Make the planet slightly denser and hence smaller, and the orbiting object won't know the difference. A point-mass can have an object orbiting at any distance above it...just expand the volume and keep the mass to get it as close to the orbiting object as you wish.
Go back to physics class or take some calculus and rethink your "go faster and you will automatically be pushed [farther out]" idea.
How come they didn't take any color pictures?
Those are very few pictures. More pictures (and picture archive) is at: http://near.jhuapl.edu/.- -------------------------
-----------------------
Jobs? Which jobs?
The only certainty is entropy.
These guys are the ones who built near. more nice pictures and some videos. Near stuff.
Do the NEAR spacecraft have a color camera ? I only find b/w photos of Eros.
How is it possible that in year 2000 it has no color camera !? The old 70's Viking Mars lander had one!
MOD THE CHILD UP!
Both of your descriptions are accurate, it is just that you are describing different things. The parent post is talking about an object that is allready in a stable orbit. In that case if you increase the tangential component of your velocity you would move into a higher orbit. What you are describing is the tangential velocity required to maintain a stable orbit, which is also true.
Just because something doesn't make sense at first doesn't mean that it is wrong, maybe you just haven't wrapped your head around it properly.
UBU
How did they come to be there given the level of Eros's gravity? If a meteor hit Eros, the debris from the impact would fly off far too fast to be recaptured by Eros, yet if the rocks aren't impact debris, where did they come from?
He's out there somewhere, travelling in a faster-than-light spacecraft..
According to Plato, Eros is the striving of mankind to the pure, the good, the beautiful. Plato said nothing about photographic artifacts in satellite fly-bys of minor planets. Anyway, back to work. Plato said he left Atlantis lying around here somewhere....
-- Anne Marie
The law in question was repealed in 1991 without any fanfare. You're now free to touch aliens all you want, as long as you make sure they aren't same-sex or under-age aliens.
-- Anne Marie
"And here we see that, yes, surprisingly, this is just a big rock. Over here we have some holes, and here, just behind that small rock, is a big rock. And there's another rock. And another one. Lots of rocks people. Great stuff."
The only fool bigger than the person who knows it all, is the person who argues with him.
I do not respond to cowards. Especially anonymous ones.
When I first read the title of this story, I didn't think it had anything to do with space exploration... I thought it was some kind of government funded study of geeks.
I wonder if any censorware program will not block it.
Dude... 30,000 km/sec is about 30% of the speef of light. You wouldn't be in orbit, you'd be heading off on an almost-linear escape trajectory (and fried by all the solar wind protons you'd be passing through, which would look like several-hundred-MeV cosmic rays to you).
--
Time is Nature's way of keeping everything from happening at once... the bitch.
If you want to try working out the orbital speeds yourself, you'll need the gravitational constant G (6.67 * 10^-11 N m^2/kg^2) plus the mass and dimensional data on the NASA page linked above.
I find it interesting that you could land on Eros with the equivalent of a big pogo stick, and launch yourself to escape velocity the same way.
--
Time is Nature's way of keeping everything from happening at once... the bitch.
--
Time is Nature's way of keeping everything from happening at once... the bitch.
--
Time is Nature's way of keeping everything from happening at once... the bitch.
This BBC article has the picture I was hoping for. Looks smoother than the Moon to me, lots of dust with a few rocks and no rims on the craters. It also contains this utterly hilarious typo:
I guess Eros is even more of a "near-earth asteroid" than anyone thought!--
Time is Nature's way of keeping everything from happening at once... the bitch.
People used the same argument to claim that the footage from the Apollo missions was faked. The argument is just as bogus today as it was 30 years ago.
--
Time is Nature's way of keeping everything from happening at once... the bitch.
http://antwrp.gsfc.nasa.gov/apod/ ap0 01026.html
I see 'Lolita' -- but where, as a friend of mine pointed out, is 'Humbert Humbert'? :)
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I watched C-beams glitter in the dark near the Tannhauser gate.
the ; pictures prove it is a rock.
Keep in mind that the orbital corrections are done with a significant time delay -- this is a situation where the speed of light *matters* :-).
Getting that close to Eros successfully is nothing short of remarkable IMO.
There was an article in Scientific American years ago about the mods made to the Voyager probes in flight (wish I could remember the specific issue), and it really gives you a feeling of wonder about the fact that we monkeys can do this stuff at all...
"Each day, each moment brings its change," Ghanima said. "One learns by recognizing the moments."
Eros? But I thought the buggers burned that to a radioactive .... ah. When did I receive security clearance to know this?
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You are right about being able to orbit at any altitude, of course, friction of the atmosphere would become significant at lower altitudes.
You were only partially right when you said that the earth's gravity pulls at 9.8 m/(s^2), actually, according to Universal Gravity, two bodies will attract eachother with a force governed by the following equation:
F=(G M m)/(r^2)
Where F is the force of attraction, G is the gravitational constant (about 6.67*10^-11 m^3/(kg/s^2)), M and m are the masses, and r is the distance between the the two bodies' centers of gravity.
That is all well and good, but it dosen't tell us what the force of attraction for the earth is. To discover that, we have to use another equation, Newton's second law:
F= m a
Where F is force, m is mass, and a is (you gussed it) acceleration.
We can set F equal to F and yeald:
m a = (G M m) / r^2
We can cancel out the two small 'm's to get:
a = (G M) / r^2
We need a 'r' and a 'M', so I will now stipulate that the radius of the earth is about 6.38*10^6 m and that the mass of the earth is 5.98*10^24 kg. An abitious slashdoter could most likely find much more accurate figures, but these will fit our purposes. Consequently, we can find the acceleration due to gravity with:
a = (6.67*10^-11 * 5.98*10^24) / ((6.38*10^6)^2)
a = 9.799 m/(s^2)I hope you can see that 'a' would be significantly less were an object higher (say, 500km) from the surface of the earth, as 'r' would increase:
a = (6.67*10^-11 * 5.98*10^24) / ((6.38*10^6 + 500*1000)^2)
a = 8.427 m/(s^2)Back to the original question: How fast must an object to travel to orbit the earth at the surface? To answer that, we have to call apon yet another equation, that of centripical acceleration in circular motion:
a = (v^2) / r
We know that the centripical acceleration is the acceleration due to gravity, which we found to be 9.799 m/(s^2) at the surface of the earth, and we know 'r' to be the radius of the earth, so to find 'v' (velocity) we could have:
v = sqrt( a r )
v = sqrt( 9.799 * 6.38*10^6) v = 7906.81 m/s v = 7.907 km/s (*)As you can see, this is significantly less than your figure of 30,000 km/s!
(*) Us Americans, who's brains have been destroyed by the English System, would get more sense out of 17,687 mi/hr.
Jordan Bettis
``Wherever you go, there's another stupid sigfile quote.''NASA already has plans for a deep space probe to sample the tail of a comet, a simple flythrough that has the potential of capturing some organic compounds. To match speed and orbit a comet all of the way around the sun is big science, whether or not the probe or comet survive. Organic compounds and water ice would rewrite the origins of life. We have to check it out.