Cassini to make audacious flyby

[TechBear_Seattle]

Cassini to make audacious flyby



Such is the interest in Enceladus that Nasa has directed its Cassini spacecraft to pass just 50km from the Saturnian moon on Wednesday.

The flyby will take the probe through the plumes of icy particles emanating from the enigmatic cracks at the south pole dubbed the "tiger stripes".

The cause of this activity has developed into the big scientific question of the flagship mission.

The pass will allow Cassini instruments to directly sample the plume particles.

This should help scientists address the tantalising issue of whether there is an ocean under Enceladus' icy crust.

The complete article can be read at http://news.bbc.co.uk/2/hi/science/nature/7289670.stm

[0007]

1. Interesting! Thanks for the link.

[Birthmark]

2. I hope the "other stuff" in the water...

...is little critters. That'd be pretty mind-boggling. And it's not entirely impossible.

[USA AOK]

3. audacity

I checked this out only because I doubted the veracity of the 'audacious' claim. Geez, 50km? That's bold as nuts, I stand corrected!

[TechBear_Seattle]

4. Public education can be a wonderful thing

You might want to look in to it. :hi:

Consider that this involves a course correction, ie straying from the way Cassini was programmed to orbit. It takes almost half an hour for Cassini's telemetry to reach the Earth, and almost half an hour for engineers to respond, assuming they do so immediately. At the speed Cassini is moving, it will have travelled several hundreds of miles before necessary corrections can be fed back to the probe. By that time, being off by one tenth of one degree could send the probe crashing into Enceladus, aimed irrevocably into Saturn or lost forever in a sling-shot out of the solar system. Imagine, if you will, trying to play Lunar Lander and having to make your moves an hour in advance.

"Audacious" is an understatement.

[USA AOK]

5. i cant play lunar lander in real time

I get the feeling you think I disagree with you. I dont. 50km is unbelievably close. Cant wait for these snap shots.

[TechBear_Seattle]

9. My apologies for my sarcastic tone

I read your post as, "Audacious? 50km? Feh! Get back to me when they are trying 5km, THAT would be impressive."

:toast:

[Ghost Dog]

17. BTW, Welcome to DU, USA AOK!

:smoke:

[Ghost Dog]

7. Enceladus at a Glance

Enceladus Flyby
Mar. 12, 2008 (SCET)

Altitude
52 km (32.3 miles)

Speed
14.4 km/sec (32,234 mph)

[Ghost Dog]

6. And passing through 'plumes' of not entirely known composition

:thumbsup:

Edit: Cassini homepage here: http://saturn.jpl.nasa.gov/home/index.cfm

[TechBear_Seattle]

8. That too

Although I believe spectroanalysis of the plumes would have shown sulphuric acid or any other corrosive or dangerous substance. However, if the probe does pass through a plume, we can pretty much say "Buh-bye" to the probe, as there will be no way to gauge how much force it has applied and thus how much it has changed the probe's course. Again, by the time we find out and can send a course correction, it will probably be too late (especially if it goes through a second plume while we are scrambling to recalculate for the first.)

[Ghost Dog]

10. The applied-force factor of the plume's push

would have been estimated and pre-progammed, wouldn't you think?

Let's see what the site says now...

[Ghost Dog]

11. 30 Minutes to go:

Cassini Status
Next Encounter:
Enceladus Flyby
50 km (31 miles)
Mar. 12, 2008 (SCET)
Countdown:
0 DAYS
0 HRS
30 MIN
19 SEC

real time, I hope... (Edit: rec'd for visibility?)

[Ghost Dog]

12. Image (10 minutes ago) (simulated):

:shrug:

[Ghost Dog]

15. Hey, this (simulated earth-view) image live-updates-itself!

cool.

[TechBear_Seattle]

16. You make a number of unwarranted assumptions

A) That the plumes be predicted, and B) that the estimates for force and timing are both accurate within a very small margin of error. Again, between the velocity of the probe and the long communication lag, this is a gamble. I'm not saying it is not a worthwhile gamble, mind you.

[Ghost Dog]

18. Agree.

You saw the publicity video?

linked here: http://saturn.jpl.nasa.gov/multimedia/videos/video-details.cfm?videoID=171

[AnneD]

13. I was watching and old

VHS tape the other day and an old new program was also recorded. They mentioned the Cassini rocket being launched. Ironic.

[FiveGoodMen]

20. Language police alert!

"If a diabetic is hit by a truck, it's a normal death.
If a diabetic is hit by a sugar truck, it's an odd and tragic death.
If a diabetic is hit by an insulin truck, it's a coincidental and oddly poetic death.
But if a diabetic is on his way to get some insulin and he gets hit by an insulin truck, then that's ironic."

-- George Carlin

[AnneD]

24. LOL

I was thinking it was ironic that they mentioned Saturn and the moons and that I happened to see this by accident last weekend (and thinking to myself-whatever happened to that Cassini rocket?). What is a miracle is that I am still alive to see the pictures-but I'll happily take the citation and conjugate a few verbs...or is the fine diagramming several sentences?

[Ghost Dog]

14. So, looks like we just flew by.

Now we await news of the consequences...

[Ghost Dog]

19. Still awaiting news...

[Ghost Dog]

21. Still no news. So bad PR for a start.

It's been 3.5 hours now.

[TechBear_Seattle]

22. It usually takes several days to process the information before it gets released

Relax! :smoke:

[Ghost Dog]

23. No problem.

(For years now, I don't use TV. Internet from (almost before) the start. So perhaps I'm used to faster/more accurate responsivity).

Folks are busy. However, there's a new post on the blog on the site:

Post-Flyby Data Less Than Two Hours Away

Saturn News | 0 Comments

Mar 12, 2008 08:30:32 PM
Todd BarberTodd Barber, Cassini Lead Propulsion Engineer (bio)

Hello again from the realm of Cassini engineering! Even though many of the engineering events of this flyby are now behind us, I wanted to take a minute to say how much the flight teams (science AND engineering) have enjoyed all your wonderful blog comments. We are chomping at the bit for the first data playback in less than three hours, just like you. A lot of hard work and planning went into this daringly close flyby of Enceladus. We hope all our efforts will be rewarded very soon.

As an engineer, I'm looking forward to seeing telemetry that would show we've come through the Enceladus flyby safely and successfully. However, as a scientist-wannabe myself, I think I'm more anxiously awaiting the first images and science results from this historic encounter.

Fortunately, my engineering "plate" has been full today, helping the hours and minutes pass more quickly. Even in the midst of this encounter, we have been preparing to open the main-engine cover and execute a roughly 17-second rocket firing on Thursday afternoon PDT. This maneuver will change Cassini's zippy speed by only 2.76 meters per second, or 6.17 miles per hour, but yet it is critical to set up our next encounter, a 1,000-kilometer (621-mile) Titan flyby on March 25, 2008. Even as we pause briefly to revel in what we hope is the success of our Enceladus rendezvous, the spacecraft always looks forward to the next encounter and a continued flood of science data. Go, Cassini, go!

Tags : spacecraft

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[YankeyMCC]

25. Bad news

http://space.newscientist.com/article/dn13467-cassini-probe-failed-to-taste-moons-geysers-in-flyby.html

"The Cassini spacecraft flew into the icy geysers erupting from Saturn's moon Enceladus on Wednesday in an attempt to figure out what they were made of, but a glitch prevented the probe from actually 'tasting' the plumes."