NASA Relies On Thrusters To Steer Space Station After Malfunction

AP via CNN ^ | December 6, 2003 | AP

[John W]

CAPE CANAVERAL, Florida (AP) -- NASA is relying on Russian-made thrusters to steer the international space station following a new malfunction with the U.S. motion-control system, officials said Friday.

Flight controllers detected spikes in current and vibration in one of the station's three operating gyroscopes on November 8. Last week, when the gyroscopes were used again to shift the position of the orbiting outpost, all three worked.

[RightWhale]

to the taxpayer, there is not a fig-newton of difference between an ivory tower electrochemist and an ivory tower physicist.

Taxpayers and votors ought to take some responsibility for getting a little education for themselves. Otherwise they are just cattle. Physicists, having an understanding of modern physics, doubted cold fusion immediately, but checked it out just in case. Nothing there but a catalytic reaction, forget it.

[Physicist]

BTW - to the taxpayer, there is not a fig-newton of difference between an ivory tower electrochemist and an ivory tower physicist.

To the average taxpayer, there's no difference between a physicist and a stock broker. You might as well lay the responsibility for ImClone at our feet.

Neither one of youall are 'aware' of money, it is like 'mis-matched socks' to youall.

And we burn American flags, too, don't forget.

[XBob]

116 - What was the advantage of the Texas project accellerator over Fermilab’s Tevatron, the world’s highest-energy particle accelerator?

[XBob]

SORRY, MAKE THAT - 116 - What was the advantage of the Texas project accellerator over Fermilab’s IMPROVED Tevatron, the world’s highest-energy particle accelerator?

[RadioAstronomer]

What was the advantage of the Texas project accellerator over Fermilab’s IMPROVED Tevatron, the world’s highest-energy particle accelerator?

Physicist, correct me if I am wrong, however, I was of the understanding the SSC was designed to produce energies greater than ten times the capability of the Tevatron.

[Physicist]

What was the advantage of the Texas project accellerator over Fermilab’s IMPROVED Tevatron, the world’s highest-energy particle accelerator?

That's an excellent question. The proton-antiproton collision energy at the Tevatron is around 2 TeV, whereas the collision energy at the SSC was to be 40 TeV. Now, you might think, "big deal, so you get 20 times more stuff at 24 times the cost", but you'd be wrong, because the stuff you would get at SSC collision energies is different from the stuff you get at the Tevatron.

Different types of particles, as I'm sure you know, have different masses. Mass, as you should know, can be converted to and from energy. Thus, what kinds of particles you can produce in a collision are determined by how much energy is available. If the collision energy is below the threshold for producing, say, a top quark, you won't ever see any top quarks, no matter how much data you take.

Furthermore, production cross sections are strongly energy-dependent. If you're just above the production threshold for a given particle, the particle will be rare, i.e. it will appear in a very small percentage of collision events. As the collision energy increases, the rare, heavy particles become more and more common.

So that's two ways in which higher collision energy always leverages our ability to do physics. But there's a more important reason for taking the next step in energy.

We have known for more than 20 years that the Standard Model of Particle Physics is incomplete. It cannot hold to all energies. By the time you get to around 1 TeV, it "breaks", and starts to give nonsensical answers, such as predicting interaction probabilities that are greater than 100%. There must be some sort of new physics that appears before that energy scale.

There are many theoretical models for what this new physics might be, and one of them--or several of them--may be correct. Or perhaps none of them is correct, and the new physics is something we haven't dreamed of. But in any case, there are discoveries to be made and models to be tested. You might have heard of the Higgs mechanism, technicolor, supersymmetry, extra dimensions, quark compositeness, or any number of other exotic theories. None has really been tested, because we haven't reached the energies where they'd be relevant.

But wait: I did say that the relevant scale was 1 TeV, didn't I? And isn't the collision energy of the Tevatron close to 2 TeV? So why can't the Tevatron see these new processes, or test the new models?

Protons are not like electrons. Electrons are--as far as we've ever been able to tell--pointlike particles. When you put energy into a collision, every bit of it is available for creating new particles. Protons, by contrast, are extended objects that are composed of a cloud of quarks and gluons. In a collision between protons, each cloud of particles passes through the other, but sometimes, an individual quark (or antiquark, or gluon) from one hits a quark (or antiquark, or gluon) from the other cloud. Each quark, however, only carries a fraction of the proton's momentum. Here's a crazy twist to it: the faster the proton goes, the more constituent particles it appears to have, so the smaller is the fraction of the momentum carried by each member of the cloud.

[Geek alert: The canonical cartoon of a proton is that it contains three quarks (two up quarks and a down quark). In reality, the proton is composed of a sea of quarks, antiquarks and gluons; the three "valence" quarks represent the excess of quarks over antiquarks inside the proton. Likewise, an antiproton will have three "valence" antiquarks.]

Thus, there is no way that the Tevatron will explore the interesting energy range, no matter how long it takes data. It is possible that it produces Higgs bosons, but the rate is so low that it will almost certainly not be able to see them (i.e., tease the signal out of the background, which requires high statistics) before the LHC turns on. That's not to say that the Tevatron won't make discoveries, or won't do a great job of measuring Standard Model processes with unprecedented precision. It's just that it won't break the Standard Model.

The energy of the SSC, by contrast, was specifically chosen to cover the entire theoretically required range for physics beyond the Standard Model. It was as close to a guaranteed scientific payoff as any experiment ever designed by man.

[RadioAstronomer]

Ping for Physicist's #126.

Wonderful read and extremely well written. :-)

[Darksheare]

Sweet.

Hopefully we observe something ALOT weirder than any expect.

[RightWingAtheist]

Thanks, RA! For further info, here are some articles on the Tevatron direct from Fermilab itself, written to commemorate its 20th aniversary last month: www.fnal.gov/pub/ferminews/ferminews03-11-01/p1.html

http://www.fnal.gov/pub/ferminews/ferminews03-11-01/p2.html

http://www.fnal.gov/pub/ferminews/ferminews03-11-01/p3.html

http://www.fnal.gov/pub/ferminews/ferminews03-11-01/p4.html

http://www.fnal.gov/pub/ferminews/ferminews03-11-01/p5.html

http://www.fnal.gov/pub/ferminews/ferminews03-11-01/p6.html

[RadioAstronomer]

Cool links :-) Thanks!

[RadioAstronomer]

Hopefully we observe something ALOT weirder than any expect.

"I have no doubt that in reality the future will be vastly more surprising than anything I can imagine. Now my suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose. ... I suspect that there are more things in heaven and earth than are dreamed of in any philosophy." - J. B. S. Haldane, Possible Worlds (1927)

[edwin hubble]

Thanks for the ping, RadioAstronomer on #126 (Physicist).

Its an important message for lay public that our understanding of particles and energies has limits. (Known limits for the Standard Model).

Physicist gives a great description of the proton as a 'cloud' or "committee" of many quarks and other particles - in a way that makes a good picture for the lay public. (and I liked the geek alert on the 'valence' quarks.)

[edwin hubble]

"Does anyone really expect the American public to give up his or her latte for ONLY ONE SINGLE day to fund a Mars mission? I sure don't."

RadioAstronomer, This is an important message about the investment that the space program projects make:

Note that the simple and straightforward language is intended not for you, but for the lurkers who may believe that we actually send "dollars into space".

1. Astronauts actually cash their paychecks and pay their mortgages on Earth, not in space.

2. Hardware for the space program is produced here on Earth and pays wages to workers here on Earth. The workers raise their families here on Earth and buy goods and services on Earth.

3. Space projects buy mostly American materials.

4. The space program had an important part in the development of the computer as we know it, global telecommunication, GIS, GPS... A good part of our present economy is due, in no small part, to the space program.

[RadioAstronomer]

Thanks :-) Well stated post.

[Darksheare]

*chuckle*
I don't know where this quote initially comes from, but here it is, "This universe is more disturbing than I originally thought."
And, said when a new particle was seen, "Who ordered THAT?"

[Physicist]

And, said when a new particle was seen, "Who ordered THAT?"

Isidore Isaac Rabi, when he discovered the muon.

[Darksheare]

Thanks.
I love that quote.

[Ichneumon]

You write pretty well for a guy who died in 1953. ;-)

[Virginia-American]

And don't forget Enrico Fermi:

"If I could remember the names of all these particles, I'd be a botanist."

[Right Wing Professor]

Here's a crazy twist to it: the faster the proton goes, the more constituent particles it appears to have, so the smaller is the fraction of the momentum carried by each member of the cloud.

Dumb question; how can the number of virtual quarks vary with velocity, what with relativity and all? Is the quark number not a Lorenz invariant?