*Live Thread* -- 7/3/05 NASA "Deep Impact" Comet

NASA / Space.com ^ | 7-3-05 | Buzz Aldrin

[FreedomNeocon]

All times are Eastern U.S. time

July 3, Sunday
7 a.m. – 10 a.m. - Deep Impact Pre-Impact Live Interviews - JPL (One-Way Media Interviews)
2 p.m. – 3 p.m. – Deep Impact Pre-Impact Update - JPL(Update on separation and navigation)
4 p.m. – Deep Impact Pre-Impact Update - HQ (Replay)
7 p.m. – Deep Impact Pre-Impact Update - HQ (Replay)
11:30 p.m. – 3:30 a.m. (July 4) – Deep Impact Commentary (Expected time of impact: 1:52 a.m.)

July 4, Monday
4 a.m. – 5 a.m. – Deep Impact Post-Impact Press
Conference - JPL (Interactive Media Briefing)
7 a.m. – 10 a.m. – Deep Impact Live Interviews - JPL (One-Way Media Interviews)
11 a.m. – Deep Impact Post-Impact Press Conference - HQ (Replay)
2 p.m. – 3 p.m. – Deep Impact Post-Impact Press Conference - JPL (Interactive Media Briefing)
4 p.m. – 7 p.m. - Deep Impact Post-Impact Live Interviews - JPL (One-Way Media Interviews)
7 p.m. – Deep Impact Post-Impact Press Conference - HQ (Replay)

(Expected time of impact: 1:52 a.m.)
Video can be streamed from here if you do not get NASA TV

[ken5050]

Thanks my friend..if anyone hears if any Nets are gonna cover it..be helpful..also, maybe another late night ping...

[Trimegistus]

In the News/Activism forum, on a thread titled *Live Thread* -- 7/3/05 NASA "Deep Impact" Comet, Vn_survivor_67-68 wrote:

"Do the flippin' math."

I guess you know everything......including the mass of all chunks that might separate.


Again: do the math. Assume the impact velocity is 1000 meters per second. Assume the probe masses 100 kilograms. Energy liberated by the impact is 1/2 mass times velocity squared, or 50 million joules.

If we assume a 1-ton chunk is the smallest fragment to worry about, and that you need a velocity change of 0.1 kilometer per second to put the chunks on a significantly different orbit from the parent comet, this means the impact -- if it was 100% efficient -- could impart a 100-meter per second velocity change to _ten_ such chunks. So _at best_ the impact could add ten small-to-medium meteoroids to the solar system. The odds of those ten bodies ever encountering the Earth are incalculably remote.

Of course, those chunks would be ice, and would vaporize in the heat of the Sun in a few months' time.

We _really_ need better math and science education in this country.

[laishly]

Ping for midnight!

[cripplecreek]

Assuming that the probe creates a crater the size of a football stadium, the material ejected will be much smaller. Much of the material ejected will be vapor.

[Vn_survivor_67-68]

to which I best reply with a question......

What percentage of weight loss causes LEO or MEO satellite orbits to decay at a faster rate than an identical and intact one?

(I am only tasked with justifying a little skepticism....you have more to do that that)

[nesnah]

Am I the only one who thinks this is a complete waste of money? I believe I read that this "mission" had a price tag of somewhere a little over $300,000,000. Stoooooopid.

[Moonman62]

What percentage of weight loss causes LEO or MEO satellite orbits to decay at a faster rate than an identical and intact one?

It doesn't matter. As Galileo proved, all masses fall at the same rate in a vacuum.

[Vn_survivor_67-68]

"Am I the only one who thinks this is a complete waste of money?"

No, you are not. NASA is nortorious for wasting money and making mistakes. They've done both good and bad. Despite the poo-poo'ing I'm getting here, I'd STILL rather they'd chosen a non-resident comet to shatter and "see what happens". Thats my only point.

[Vn_survivor_67-68]

".....all masses fall at the same rate in a vacuum."

LOL

And this is relevant BECAUSE........??

[Williams]

Please don't worry about altering the course of this one comet or of the whole system. Many comets orbit the sun in long eliptical orbits of 10,000 years, 100,000 years or more in duration. That is why comets never before recorded by man often show up unexpectedly. It's always been my pet theory that an enormous wave of comets is out there beyond our observational capability, and will utterly devastate the surface of Earth when it makes its next return. Only glitch is, I don't know if it will be spotted on its way in tonight or one million years from now. So you see, there is no need to worry.

[hispanarepublicana]

Ah, somebody please explain to me like I'm a kid: Why are we doing this? (truly asked from the standpoint of ignorance not sarcasm)

[IllumiNaughtyByNature]

Ping for late night FReep session.

[OSHA]

At least you were able to explain it without being arrogant and condescending. < /sarcasm >

[Trimegistus]

In the News/Activism forum, on a thread titled *Live Thread* -- 7/3/05 NASA "Deep Impact" Comet, Vn_survivor_67-68 wrote:

to which I best reply with a question......

"What percentage of weight loss causes LEO or MEO satellite orbits to decay at a faster rate than an identical and intact one?

(I am only tasked with justifying a little skepticism....you have more to do that that)"

I have no idea what you're trying to say here. Satellite orbits usually decay because of friction with the upper atmosphere. In the case of satellites with no more thruster fuel to compensate, the result is fatal.

[OSHA]

As Galileo proved, all masses fall at the same rate in a vacuum.

And where, pray tell, did Galileo get a vacuum? Wal-Mart hadn't been invented yet. The level of scientific ignorance on this thread is astounding. :^) < / imitate Trimegistus >

[Howlin]

LIVE THREAD HERE!!!

[FreedomNeocon]

Orbit-altering crash
A'Hearn said that while most NASA missions are passive in terms of how they explore an object, Deep Impact is "completely different, because it is a real experiment in which we do something to another body in the solar system and see how it reacts."

And how. The 770-pound (350-kilogram) probe will hit the comet at 22,300 miles (35, 885 kilometers) per hour and penetrate 16 to 32 feet (5 to 10 meters). Much, but not all of the probe will be vaporized.

Then a bunch of the comet's innards will spew outward at about half the speed that the projectile came in. Over the course of about 200 seconds, more material will be excavated, carving a hole as big as a football field and seven stories deep.

Before impact, the comet will be visible in a good amateur telescope. But the freshly ejected material will enlarge the halo of debris around the comet, off of which sunlight reflects, and it will brighten dramatically.

"It should be easily visible in good binoculars, and it might be easily visible with the naked eye," A'Hearn said in a telephone interview.

The impact will be strong enough to alter the comet's orbit, and there has been some public concern over whether humanity's impact of a comet might alter its orbit enough to cause it to threaten Earth.

No such retribution is possible, A'Hearn said. The comet's present orbit would never come within 50 million miles (80.5 million kilometers) or so of our planet, and the force of the probe's impact won't change that by more than 330 feet (100 meters).


Why do it?
The point of the impact, of course, is to learn about comets. But comets never sit still. At least not until they crash into a planet or something.

This propensity to threaten their neighbors -- which can make a planetary mess of things -- makes comets supremely interesting to scientists, who still know very little about what's inside the icy bodies with their long, wacky orbits around the Sun. Some comets travel a fifth of the way to the next nearest star.

And then there's the fact comets hoard a vault of pristine information about the formation of the very planets they like to smash into. The recent breakup of a comet provided researchers with an unprecedented view of its nucleus, and scientists were thrilled at what they learned.

Along with ground-based observations, a camera and an infrared spectrometer on the Deep Impact mother ship will watch the action. A'Hearn said that after the mother ship has transmitted all the data back to Earth, which will take about two days, the craft is slated to be abandoned to wander through the solar system.

"There are currently no plans" to utilize the mother ship for any further purpose, A'Hearn said.

Comet Tempel 1, the target, was discovered in 1867. It's what is called a short-period comet, orbiting the Sun every five and a half years.

Scientists are eager to learn whether comets exhaust their supply of gas and ice to space or seal it into their interiors. They would also like to learn how a comet's interior is different from its surface.

Creating a crater in a comet is also expected to teach researchers how craters form.

A side benefit of the mission is that it will teach researchers something about how to deflect a comet or asteroid, in the event that one ever is heading our way.


Sister missions
Deep Impact is the seventh mission in NASA's Discovery program, which seeks lower-cost, highly focused missions. The first of these was the 1997 Mars Pathfinder lander and rover. More recently, the Near Earth Asteroid Rendezvous (NEAR) spacecraft orbited Asteroid 433 Eros for a year, then in a late change of plans landed on it on Feb. 12, 2001.

[RightWhale]

Okay.

[RightWhale]

Why are we doing this?

Excellent question. Keep an open mind and part of the answer will become available.

[NormsRevenge]

Well, at least we will soon know if we can hit a moving celestial object with something bigger than a Yugo should we ever need to divert an object.

$300 Million,, cheap if it works.. our gubamint looking out for us. :)

(ducks under the table to avoid hurled objects)