If there is no plutonium on board the satellite then why is the navy using a heat seeking missle?

The engine has been off for awhile... the only heat on the damn thing would be from the reactor.

They're going to hit it shortly after it passes from sunlight to shade. Since space is a vacuum, heat dissapates slowly, so the thing will be much hotter than its surroundings for a while - it will be a very easy target.

that's why it's "falling out of control"...

These satellites are monitored carefully and when they reach the end of their useful lives they are usually guided into a controlled re-entry at a specific place, away from population centers and especially away from hostile territory not controlled by the USA.

This is no accident; this is target practice.

It does not add up.

orbit, so it wasn't motoring around like whatever the okay ones do.

This is the reason they're using, in any event - truthful or not.

the tank will rupture during re-entry and the fuel will burn off in the stratosphere.

But if it falls in Russian or Chinese territory, the loss of technical secrets would be enormous.

Forget the fuel; that's the real risk.

:7

simple as that.

because the satellite died on arrival. The hydrazine is stored in a titanium vessel. That titanium can resist 3000 F on reentry.

That's not the real issue.

now it's the computers...

Next?

oh right, control system.

oh right, aerospace engineers don't know nothing about no critical system redunancy.

At this point, it's guess work. But seriously, do you think they would waste a brand new satellite for this test? Someone somewhere is really pissed off that his project failed in space.

It would be cheaper and easier to de-orbit a satellite at the end of its lifespan and use that instead.

No solar panels, no power. No power, no 'puters.

Unless it was equipped with a different power source... which nicely explains the urgent necessity to shoot it down.

Usually you get into position, then deploy them. If the computers went down prior to that as they did, well, you can figure out the rest.

And get a fucking clue.

and get some manners.

And if you have aerospace experience, let me know.

I've had a bad day. Was the satellite dead? Is there hydrazine in a titanium vessel that could withstand the heat of reentry? What is your aerospace experience?

Mostly shuttle. You can do a search on my earlier posts at DU for validation.

I haven't followed the satellite story in detail (frankly, I don't believe them), but I have been expecting the US to send a message to Russia and China regarding our ability to kill ICBMs. Especially after the push back on missile shields in Poland, Ukraine, and Turkey.

And no problem; I understand bad days. I've had a few recently. :hi:

is the best way to kill the hydrazine? BTW, which shuttle missions did you work on?

Old I know, but still pertinent.

The heat of reentry is more than twice the necessary to melt titanium, assuming the heat itself wouldn't cause the tanks to rupture.

http://en.wikipedia.org/wiki/Atmospheric_reentry

The tools might be a bit different but the rules are the same.

I was all of four years old when it re-entered. Wiki has a picture of the largest piece of Skylab to survive and it looks much smaller than I think a fuel tank would be (although I could very well be wrong).

oh well. No internet to archive the articles back then...

Wiki is not the arbiter of fact (neither is the internet).

I'm in awe. I was 16 at the time, living in Phoenix, and I got up before 5 AM (IIRC) to watch this. Note: I am NOT a morning person and believe that if God meant me to see the sunrise, he'd have made it later in the day. That's how excited I was.

Thanks for the link. That's a lot to absorb. What is the temperature at reentry for something shaped like the hydrazine fuel pod?

Thanks in advance.

and a great deal of collective guilt for the loss of Challenger and Columbia.

To answer your question:

H. Julian Allen and A. J. Eggers, Jr. of the National Advisory Committee for Aeronautics (NACA) made the counterintuitive discovery in 1951<1> that a blunt shape (high drag) made the most effective heat shield. From simple engineering principles, Allen and Eggers showed that the heat load experienced by an entry vehicle was inversely proportional to the drag coefficient, i.e. the greater the drag, the less the heat load. Through making the reentry vehicle blunt, air can't "get out of the way" quickly enough, and acts as an air cushion to push the the shock wave and heated shock layer forward (away from the vehicle). Since most of the hot gases are no longer in direct contact with the vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere.

...

An approximate rule-of-thumb used by heat shield designers for estimating peak shock layer temperature is to assume the air temperature in kelvins to be equal to the entry speed in meters per second. For example, a spacecraft entering the atmosphere at 7.8 km/s would experience a peak shock layer temperature of 7800 K. This method of estimation is a mathematical coincidence due to peak heat flux for terrestrial entry typically occurring around 60 km altitude.

It is clear that 7800 K is incredibly hot (the surface of the sun, or photosphere, is only 6000 K). For such high temperatures, the air in the shock layer will break down chemically (dissociate) and also become ionized. This chemical dissociation necessitates various physical models to describe the air's thermal and chemical properties.

End of quote.


I would add that the shuttle reenters the atmosphere at mach 25, approximately 25,000 ft/s. Using an approximation of 3 feet = 1 meter, that's 8.8 km/s or 8,800 degrees Kelvin.

In general that's the upper range of speed of reentry, and thus the upper range of temperature. If you went any faster, you would still be in orbit.

The hydrazine tanks are probably spherical or at least cylindrical; about as close to blunt objects as you can get.

But the connectors to the satellite rockets are a different matter. I would expect those to burn off first, and the hydrazine to escape through those openings.


Best regards,

Xipe :hi:

for Columbia and Challenger. As a friend of mine, now departed (Former F-5 pilot and instructor, B-52 pilot) once said. Shit happens. Sometimes there is nothing you can do to prevent it.

Enough to melt titanium.

That's why the shuttle has a ceramic tile skin.

http://en.wikipedia.org/wiki/Atmospheric_reentry

The internal shell of the tanks are titanium, thick enough to prevent micro-meteor or orbital debris from puncturing the tanks. Probably on the order of 1 to 2 inches thick to repell speeds of up to 22,000 mph. The tanks are then wrapped in kevlar and a thermal coomposite wrap to prevent heating during exposure to direct solar radiation.

During re-entry, the plasma would have to first burn off the insulation wrap, then the heat will begin to build on the tanks. The kevlar would burn off next, continuing to retard the heating of the titanium lining as the tank tumbles. the tumbling would increase the overall surface area that would be heated, dispersing the heat as opposed to a focused point. Then the titanium would have to be kept under a maintained heating before it will rupture.

I don't know the length of time, but it would have to maintain 7800 degrees for an extended period of time, time reduced by the wrap. I believe it to be a highly probable scenario.

I will say again though, if this is not a ruse in the first place.

That's 589 degrees K.

Kevlar will be the first to burn off.

Nice try.

it's not at the end of its life. It just never worked properly. The suspicion is that solar panels never deployed properly.

The reaction control motors are used in orbit to align the sat over targets. Since they lost communications with the sat when it went dead after launching into orbit, they have no way to order it to dump the fuel before re-entree.

This is what the problem is, if this whole thing ain't just a sham.

And remember their unfamiliarity with truth, honesty, or sincerity.

You didn't even know that the satellite had died immediately after launch into orbit.

But the story doesn't add up.

If anything, it makes things even more suspicious.

It's one thing to use an aging satellite that is falling out of orbit as a target of opportunity.

Quite another if it just happens to be a new satellite, and you just happen to have the right missiles laying about somewhere that you can use to "Solve a serious safety problem".

This is no accident, this is a scheduled test.

They are adjusting the software and developing a special warhead, but most of it is existing.

The US has been itching to test satellite hunter-killer technology for years.

And under current arms reduction treaties this is forbidden.

Oh, yea. They do.

The only thing missing is the field test, and this is it.

http://www.govexec.com/dailyfed/0208/021808ap1.htm

In a matter of weeks, three Navy warships - the USS Lake Erie, USS Decatur and USS Russell - were outfitted with modified Aegis anti-missile systems, the ships' crews were trained for an unprecedented mission, and three SM-3 missiles were pulled off an assembly line and given a new guidance system.

This rapid modification only happens in the movies.

All it takes is the money. There are plenty of engineers to design and build the work. They just need lots of cash to lubricate the way.

As a first of its kind, the shootdown scenario draws on a wide range of scientific and military technologies - from ships and radar sites in the Pacific to high-powered telescopes in Hawaii and elsewhere, to a specially fitted Air Force plane and a Navy ship that snoops on missile tests.

To kick off the planning, the government assembled a high-security team of about 200 people - Navy scientists and missile defense experts, plus representatives of defense contractors Lockheed Martin and Raytheon, as well as scientists from the Johns Hopkins University Applied Physics Laboratory. Lockheed is the manufacturer of the Aegis system and Raytheon makes the SM-3 missile.

The Lake Erie, a cruiser that has participated in a dozen mostly successful tests to intercept a mock enemy missile in flight over the past six years, would take the first shot at the satellite at a distance of about 150 miles, just beyond the reach of Earth's atmosphere.

The SM-3 missile aboard the Lake Erie is equipped with a heat-seeking sensor that has been modified in order to enable it to zero in on the satellite, whose heat "signature" is smaller than that of a ballistic missile in flight.

The SM-3 costs $9.5 million, not counting its one-of-a-kind modifications. It is designed to destroy its target not by detonating an explosive nearby but by slamming directly into the satellite at high speed.


http://www.govexec.com/dailyfed/0208/021808ap1.htm

:rofl:

Oh, and congratulations on a sucessful kill on the first attempt.

http://news.yahoo.com/s/nm/20080221/ts_nm/usa_satellite_missile_dc_9

What are the odds, huh?

it never deployed. The fuel tank is full.

I hadn't read the cover story before I posted.

The tank is full.

Of what, I'd rather not say.

:hi:

I heard a conspiracy theory today that it has nuclear stuff on board. That's why they are so anxious to not have it bounce down on us and would rather blow it up in space instead.

and the sun will heat it up well above background temps

No tinfoil time here needed, just basic physics and basic orbital mechanics

What they would do is use the remaining hydrazine to burn retros and slow it down enough to come down. Personally, I think there's a scuttling charge on board that they'll trigger and claim the missile hit it.

heat-seeking part of the missile wouldn't be of help, because of the reason you cite.

..that must be destroyed for some reason. I can't remember all the details, but they are dead serious.

This stuff is on the Internets. I didn't ask for the link, as I'm somewhat skeptical of this theory. :eyes:

:-)

to shoot something out of space (approx 150 mi above earth). And the missile has other methods of programming and control.

But, I think the Navy wants to test the new missile and now has a good (enough) reason to do it...

nt.

http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

And it would likely be shielded deep inside and releasing little heat if it had one. I'd go with the satellite is warmer than empty space option.

The thermoelectrics are for powering electronic equipment.

That's the rockets.

hence the randomness.

Where do you think the thermo part of thermoelectric comes from?

Electricity - Computer

Catch my drift?

There is more than just the control systems. There is the main payload (whatever its purpose).

Thermo is the heat source. The heat source is the nuclear reactor. The heat is converted to electricity.

Hence thermoelectric.

Get my drift?

Yes I have explained several times.

But you seem to be unfamiliar with the terminology.

I said RCS (rockets) are used for orbital adjustments and attitude control.

Thermoelectric (nuclear) is used to power electronics.

Is it clear now?

I noted that they could use a radioisotope thermoelectric generator rather than a reactor (as in the Pressurized water kind known as your local electric power station).

A reactor is also a word that means rocket. Hence REACTION Control System.

That's why I mentioned RCS.

When I saw the word reactor in the context of a satellite, I interpreted it to mean rocket, not nuclear reactor.

I had stated my link to remind people how plutonium provides energy in space. I thought that could be misinterpreted.

Nuclear science isn't a well known topic among every day people. sadly.

No? :shrug:

Basic physics really. The sun will heat that satellite quite a bit above background temperatures

Radiation is the only way to shed heat without a medium for convection.

if you did not, explain why one side of Mercury is over 1000 degrees, and the other is in the 200...

Planet is tidally locked and NO atmosphere.

Hell, even astronauts avoid direct sun light, because of the heat

I was agreeing with you - the sun is certainly sufficient to heat up the satellite. My point was that convection was not available to cool the satellite as it is in our atmosphere when something gets heated by the sun. The satellite doesn't have to get very hot, either - IIRC space is ~2-3 K.

sorry...

I hope the extremely basic physics class helps folks

:-)

I could have gotten here for free.
:eyes:

for what's really up there.

The real goal was to smash to pieces a mirror or digital sensor beyond anything we know to pieces, to ensure it burns up in re-entry. There's probably a few billion dollars invested ina single sensor, which was so far ahead of everything it would blow the mind of any country that got their hands on it. So, they blew it up because it failed to launch, probably due to some stupid programming error.

C'mon now. They were getting sub 3" resolution in the 60's, they launched something that could probably get a half inch resolution, with the AI to both track the target and cover it enough to get a 3D model down to the half foot in 3D as it passes over.

You think they'd let anyone get their hands on that?

Hydrazine is just a cover. Get real.

Go US. I wish I could work on something that state of the art.