NASA's Cassini Probe Begins Its 'Grand Finale' Through Saturn's Atmosphere (space.com) 44
An anonymous reader quotes Space.com:
After orbiting Saturn for more than 13 years, NASA's Cassini spacecraft is getting ready to say goodbye. On Monday (August 14), Cassini made the first of five passes through Saturn's upper atmosphere, kicking off the last phase of the mission's "Grand Finale." After completing those five dives, Cassini will come back around again one last time, plunging into Saturn's atmosphere on September 15. This will be a suicide maneuver: Cassini will burn up in the ringed planet's thick air, turning into a meteor in the Saturn sky...
Cassini's radar will be able to look into the atmosphere and see features as small as 16 miles (25 km) wide, about 100 times smaller than what it could see from its usual orbital positions. The Grand Finale will include one final swing by Saturn's largest moon, Titan, on Sept. 11. Titan's gravity will slow Cassini's orbit around Saturn and bend its path to send the spacecraft toward its September 15 encounter with the planet... Cassini will keep sending back data on September 15 until it gets to an altitude where atmospheric density is about twice what it encountered during its final five passes, NASA officials said. At that point, mission controllers will lose contact with the probe because its thrusters won't be able to keep Cassini's antenna pointed toward Earth; there will simply be too much air to push against.
The second dip happens this weekend, and NASA has created a special web page tracking Cassini's current location for its final 28 days.
Cassini's radar will be able to look into the atmosphere and see features as small as 16 miles (25 km) wide, about 100 times smaller than what it could see from its usual orbital positions. The Grand Finale will include one final swing by Saturn's largest moon, Titan, on Sept. 11. Titan's gravity will slow Cassini's orbit around Saturn and bend its path to send the spacecraft toward its September 15 encounter with the planet... Cassini will keep sending back data on September 15 until it gets to an altitude where atmospheric density is about twice what it encountered during its final five passes, NASA officials said. At that point, mission controllers will lose contact with the probe because its thrusters won't be able to keep Cassini's antenna pointed toward Earth; there will simply be too much air to push against.
The second dip happens this weekend, and NASA has created a special web page tracking Cassini's current location for its final 28 days.
Re: (Score:3)
Re: (Score:3, Funny)
Re: (Score:2)
Re: (Score:2)
The density is a gradient, not a constant. The lower you get, the denser the atmosphere gets.
It's like saying balloons can't work on Earth because the atmosphere is too thin 100km out.
Re: (Score:3)
The density of the atmosphere goes up as you go down. So does the density of whatever gas you fill your balloon with, because it is under the same pressure as the surrounding atmosphere, or slightly larger. Which brings us to the next question.
What do you propose to fill your balloon with? The atmosphere outside is mostly hydrogen (96.3%) with a bit of helium. Your typical helium-filled weather balloon would sink right through, and your not-so-typical hydrogen-filled balloon would only float without any pay
Re: (Score:2)
Re: (Score:1)
Not feasible regardless of heating method.
My back-of-the-$100-bill calculations show that in typical upper Saturnian atmosphere conditions you can get at most 80 g / m^3 of lifting power even if you heat the gas 150 K delta T. So in order to lift just Cassini's RTG (57 kg; you probably need it all in order to communicate back to Earth) you would need something like a 800 m^3 envelope, that would by itself weight something like 20 kg at least. So in order to lift something useful you would need to increase t
Re: (Score:2)
Re: (Score:3)
I don't think you know what basic research actually is.
Re: (Score:3)
I've done basic research in the 1980's. I had to learn how do to a "FOR" loop, so I researched it.
Re:How does this affect anyone? (Score:5, Informative)
You're going to be modded into oblivion because you do not seem to have a grasp of what basic research entails. Basic research is performed in the hopes that there might be something useful that is discovered that can benefit humanity. That can include simply enriching our knowledge base. It could also be something more tangible that has vast economic benefits. Scientists, a priori, do not know what the outcome will be.
Moreover, it appears that you can't be bothered to actually use a decent search engine to answer your questions. You just assume that because you don't immediately know the answer that there isn't an answer that will satisfy you.
Here's just a brief list of what we've learned since launching the Cassini probe and other scientific instruments:
https://www.sciencedaily.com/releases/2016/10/161005131031.htm
https://www.sciencedaily.com/releases/2016/06/160621115743.htm
Some of Saturn's moons, such as Dione and Enceladus, have sub-surface oceans that might contain life. This is may provide some partial answers as to how life started on Earth or if we are alone in the universe. Moreover, such lifeforms may be vastly different than the ones found here on Earth. There may be components of those lifeforms that could prove useful
https://www.sciencedaily.com/releases/2016/07/160706115129.htm
https://www.sciencedaily.com/releases/2015/02/150227181333.htm
We've found potential traces of pre-biotic life conditions on Saturn's moon Titan.
https://www.sciencedaily.com/releases/2015/08/150805075742.htm
Scientists have a better understanding of the distribution of particles in the rings of Saturn. This model can be applied to other systems, where particles merge, colliding with slow velocities and break into small pieces colliding with large impact speeds. This finding may prove useful in non-space disciplines.
https://www.sciencedaily.com/releases/2013/04/130430131525.htm
https://www.sciencedaily.com/releases/2013/02/130219163211.htm
https://www.sciencedaily.com/releases/2012/12/121203090031.htm
https://www.sciencedaily.com/releases/2012/09/120928085222.htm
https://www.sciencedaily.com/releases/2012/06/120625150557.htm
We've come to better understand the physical processes either on or near Saturn and its moons. This may help us, in some way, in the future. At the very least, it provides a more complete picture of how other planets in our solar system behave.
Some of the findings may prove useful in an economic fashion. They may not. Either way, it's incredibly myopic to believe that certain types of basic research, including space-based research, is useless. Funding for it provides a means of training the next generation of scientists and engineers. Some of those people will move on to other fields and make breakthroughs that have a massive impact on society. Others will be high-wage earners that, combined, pay more in taxes than the original cost of the research programs.
In my case, I earned my Ph.D. in a lab that was heavily funded by the NSF, DOD, and NIH. Some of our research had no immediate practical applicability. Other endeavors were spun off into companies that were later sold. Additionally, all of my colleagues from my time in the lab now earn well into the $200-500k/yr range. We now pay far more in taxes each year than we received from grants to cover the cost of our salaries and tuition as Ph.D. students. Without the training that we received as students, we likely wouldn't be making nearly as much today.
Lastly, there are other benefits that come about from these space-based research projects. We learn to build better, more efficient rockets. We design more powerful instrumentation. We become more adept at exploring space and establishing a presence on other planets. All of these things will help us if and when we finally venture forth into space to establish temporary bases or full-on colonies.
Re: (Score:1)
Yew sownd lak one of them leetists. Yew thank yer bettr n reel peepl. Yew shud go bak ta yer librul frenz an yer librul waaf, wat you arnt even related to, an shut up cuz we runnin the cuntree now.
Re: (Score:2)
Its always the same guy, the same sad argument, you can almost hear the guy cry to sleep over some traumatic event in the past. Maybe an astronaut stole the love of his life?. In any case. Please do not feed banquets to the trolls.
Re: (Score:1)
Re: (Score:2)
With the exception of my tax dollars being pissed away, this doesn't affect me or anyone else. Perhaps a few scientists got paid off taxpayer money to do this, but how does this matter? Nobody is going to visit Saturn and nobody can live there. Can anyone explain how this matters? The whole basic science research is bogus because we can fund basic science research that is actually worthwhile. This is not, and I highly doubt anyone can justify this wasteful spending. I'll surely be censored to -1 by moderators who want to avoid this question, but that only confirms that this research is useless.
You don't think learning new things about our solar system and its planets is valuable? Sometimes outcomes lead to unexpected things. Sometimes new technology is invented for the mission that ends up being used for other things in other areas.
Did you know that the CMOS sensor in your smartphone was developed by JPL for space missions? At the time you probably wondered what the point was of exploring space. But now you have a neat little camera in your phone because of it. The point is, you don't know w
Do we know enough about exobiology to do this? (Score:1)
If it turns out that Enceladus and Titan are sterile, but that Saturn has life, then this action by NASA will be quite a blunder.
Re: (Score:2)
Re-entry at Saturn orbital speed should completely evaporate the probe, no chance of anything surviving. It took real heroics on the Galileo probe to survive Jupiter re-entry
Re: (Score:2)
Errrm you mean entry right, I mean it hasnt been there before...
Re: (Score:2)
We know enough about Earth biology to know that any microbes will not survive in Saturn. That's what matters for preventing contamination.
Re: (Score:1)
how to break a globehead in 2 seconds flat, every time,
you break me just by existing already. we as a society desperately need a license to procreate.
Re: (Score:2)
Want to know how to break a globehead in 2 seconds flat, every time, without fail? Point out that we see light in a vacuum. If he or she does not believe you, then point out MIT feather vacuum Youtube video. Then point out how space should be 100% light everywhere from the sun's rays reaching us and beyond. You're welcome. https://www.youtube.com/watch?... [youtube.com]
What? Why should space be 100% light everywhere?
Such a waste! (Score:2)
They should bring the probe back to earth to recycle the components into new probes.
Re: (Score:3)
That would have made the probe prohibitively heavier due to the huge amount of propellant needed for the return journey.
Also, the electronics are obsolete (30 years old) and radiation-damaged, so why bother retrieving them? The only component it'd make sense to recycle is the RTG (which should be at 70% of its original capacity by now).
SAVE CASSINI! (Score:1)
What do they call it? (Score:1)