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TechnologyWe're scientists, engineers & communicators for NASA's Cassini mission, which makes its #GrandFinale plunge into Saturn next week. AUA!

Sep 8th 2017 by NASAJPL • 18 Questions • 94 Points

Our short bio: After two decades in space, NASA's Cassini spacecraft is nearing the end of its remarkable journey of exploration. Having expended almost every bit of the rocket propellant it carried to Saturn, we will deliberately plunge Cassini into the planet on Sept. 15. Why? To ensure Saturn's moons will remain pristine for future exploration—in particular, the ice-covered, ocean-bearing Enceladus, but also Titan, with its intriguing pre-biotic chemistry. Only one week remains before the spacecraft's final chapter in the skies of Saturn. What would you like to know about the science and engineering still to come for Cassini? Ask us anything!

Update at 5:11 p.m. ET: We took your questions on Friday, Sept. 8 from 3 to 5 p.m. ET (noon-2 p.m. PT, 1900-2100 GMT). Time to log off and get back to the final week of the Cassini spacecraft. Thanks for joining us here today! We hope you'll be watching on Sept. 15 during the final plunge as we stream live from mission control: http://nasa.gov/live

  • Molly Bittner, Cassini systems engineer
  • Bonnie J. Buratti, Cassini scientist
  • Scott Edgington, Cassini deputy project scientist
  • Jo Pitesky, Cassini science planning & sequencing

  • Bill Dunford, Cassini social media manager

  • Preston Dyches, Cassini media rep

  • Doug Isbell, NASA-JPL science communication specialist

  • Stephanie L. Smith, NASA-JPL social media supervisor

More info on Cassini's #GrandFinale: https://saturn.jpl.nasa.gov/mission/grand-finale/overview/

GrandFinale trailer: https://saturn.jpl.nasa.gov/resources/7628/

Our Proof: https://twitter.com/NASAJPL/status/906236473237577728

Q:

I'm sure the science that came out of the Cassini mission has been great, but from a lay-perspective the photography has been absolutely stunning. I always thought that being the "mission photographer" (planning the camera activity) for a planetary probe would be probably the best job in the world.

  • What is the thought process for balancing scientific value vs purely aesthetic/outreach value in how the cameras are used? If there's a chance for a really spectacular shot, is the team willing to alter the orbit? That kind of thing.

  • What kind of stunning photography can we expect from the final approach?

A:

We try and choose the most scientifically valuable images, but beauty counts too. Occasionally we just go for the spectacular photo op. To change an orbit, though, we need a compelling scientific reason. The final shot (the day before mission end), we will get spectacular images of the clouds of Saturn. --Bonnie


Q:

Which picture that Cassini has taken best represents how a human would see it with their naked eye?

A:

Great question! It's always been important to Cassini's imaging team to be faithful to the natural appearance of the Saturn system, and they've worked hard to ensure the color is as accurate as possible. One great example is https://photojournal.jpl.nasa.gov/catalog/PIA06193 -- Preston


Q:

If you could do it over again with today's technology; what instrument(s) on the spacecraft would you add and what would you remove?

A:

There's a kid's picture book called "More More More Said the Baby"--replace "baby" with "scientists" and you've pretty much got the general feeling.

What I would add is a heck of a lot more capability to the Deep Space Network, which is the only way in which we can get information from our distant spacecraft to us (and send them instructions). Cassini only "speaks" with the DSN about every 2-3 days, and sometimes it has to use lower data rates than we the flight team would like. I would love to be able to not worry about getting enough time on the big 70 meter antennas with their sweet sweet downlink capability - Jo


Q:

I know the reason you want to burn up Cassini in Saturn's atmosphere is so you don't contaminate any of Saturn's moons. But Is that really a possibility? Wouldn't Cassini just stay in orbit around Saturn forever?

Additional question: What is Saturn composed of? Is it mainly hydrogen?

A:

This is true. The chance of Cassini impacting one of the moons is very small, but the chance is not zero. Additionally, the science that can be gathered when the Spacecraft plummets through Saturn has been determined to be the most valuable way to end the mission. -Molly


Q:

Your work is constant inspiration to so many people. To me, Cassini and the images it has sent especially. Which is why I was happy about your #CassiniInspires campaign (had to create a poster of the final moments to honor the end of this 20 year old mission)

Will you be releasing some collection of all the artwork somewhere?

Also will you be having some kind of live stream of the final moments? Or just the JPL panel afterwards

A:

Q:

Is there anything you hope to learn from slamming Cassini into Saturn? Will it be able to broadcast any vital information before it burns up?

A:

Cassini is doing a quick costume change from orbital mission to planetary probe. That means that the spacecraft will be sampling the upper part of Saturn's atmosphere, and blasting back that precious data almost as soon as it's recorded on board. That's all been carefully planned to maximize science return. - Jo


Q:

If you could do anything different about the Cassini mission, what would it be (if any)?

A:

The original design had a scan platform, in which the instruments could have been pointed independently from the spacecraft. In my opinion, it would have been nice to have had such a platform, so we could take remote sensing and dust/charged particle measurements together. And of course a longer mission would have been nice, at least through a full Saturn year. Bonnie


Q:

Is there any way for the public to follow the telemetry in realtime during the final moments?

A:

Yes! We'll be live streaming from inside mission control at http://nasa.gov/live, http://youtube.com/nasajpl and http://facebook.com/NASAJPL. You can also see a realtime simulation of the spacecraft views at http://eyes.nasa.gov/cassini and signal downlink via the Deep Space Network at https://eyes.nasa.gov/dsn/dsn.html Happy streaming! -- Stephanie


Q:

Will it go down near the poles or near the equator?

How deep into the atmosphere can it go before it can no longer transmit radio back?

Where will the cameras be pointed as it sinks?

A:

The spacecraft is entering near the equator. Due to the speeds that Cassini is traveling at, we will only hear the spacecraft for a few minutes before signal loss. Cassini's fields and particles instruments will be sampling the atmosphere as it enters. The region sampled would be roughly equivalent to the altitudes where satellites, ISS, and the space shuttle flies. Due to the placement of Cassini's cameras relative to the fields and particle instruments, the cameras will be pointed into empty space with the exception of one very quick cut across the rings. -Scott


Q:

Thanks for the reply, Scott. It made me check out the details of the sensors and found this

https://saturn.jpl.nasa.gov/cosmic-dust-analyzer/cda-technical-write-up/

How fast is the CDA? From reading what's on there, I couldn't really figure out how it works (pictures would've helped) but it made me wonder how insanely fast it must be at analyzing whatever comes inside.

A:

Here are a couple of visualizations showing the expected path: (https://saturn.jpl.nasa.gov/resources/7752/) | (https://saturn.jpl.nasa.gov/resources/7756/) -- Bill


Q:

With all of the great science that we have gotten out of both Galileo and Cassini, why hasn't there been more of an effort to launch flagship orbiters for Uranus and Neptune? As intriguing as Europa and Enceladus are with liquid oceans, I am disheartened to know that the extent of our knowledge for the ice giants are limited to the Voyager 2 fly-bys from 30 years ago. With Uranus and Neptune, we don't know what we don't know!

A:

We would LOVE to have those missions going to ice giants. They're far away, hence that much more difficult to get to. See https://www.jpl.nasa.gov/news/news.php?feature=6942 to learn more about upcoming plans. - Jo


Q:

What is the team's 'most favorite' pic by Cassini? :)

A:

There are so many that it's hard to choose. But take a look at these: (https://saturn.jpl.nasa.gov/galleries/hall-of-fame/) | (https://saturn.jpl.nasa.gov/mission/top-tens/images/) Many team members are partial to the images where Saturn is backlit by the Sun, like this one: (https://saturn.jpl.nasa.gov/resources/3315/) --Bill


Q:

I think you've done a notable job on social media outreach, especially on Twitter (which is where I spend most of my own time).

What sort of insights have you gained over the past year, in terms of connecting with people who maybe weren't aware of the Cassini mission?

Thank you so much for all of your work! It's been amazing to watch, and I appreciate the fact that you've dedicated so much effort to engaging with us regular folks. Can't express enough gratitude.

A:

So gratifying to hear. What really helps is that we have a treasure trove of gorgeous images that help tell the story. --Bill


Q:

I think you've done a notable job on social media outreach, especially on Twitter (which is where I spend most of my own time).

What sort of insights have you gained over the past year, in terms of connecting with people who maybe weren't aware of the Cassini mission?

Thank you so much for all of your work! It's been amazing to watch, and I appreciate the fact that you've dedicated so much effort to engaging with us regular folks. Can't express enough gratitude.

A:

I'm going to work on the mission's closeout phase for the next year. In addition, I'm a line manager for JPL's Science System Engineering group. - Jo


Q:

When did you have doubts with Cassini, if ever? Can you guys recall that one moment you were like 'uh-oh" regarding this mission?

A:

Whenever you do something for the first time on the spacecraft, there's always a bit of nervousness.

Sometimes you get a bit more nervous. A group of us were at a meeting out of town, having dinner. One person was one of the engineers responsible for overseeing the spacecraft during that particular "sequence" (meaning, 6-10 weeks worth of commands). This was during one of the first times that the spacecraft flew between the rings and Saturn. During dinner, her phone rang: it was the ACE, calling from JPL, to say that the Deep Space Network had not heard from Cassini when expected. =8-O

Turned out that there was a problem on the ground, not with the spacecraft--Cassini was just fine. But for a moment, that was very very 'uh-oh'. - Jo


Q:

When did you have doubts with Cassini, if ever? Can you guys recall that one moment you were like 'uh-oh" regarding this mission?

A:

Saturn held many surprises, including the plume of Enceladus and how Earth-like Titan is in some ways. Here are some highlights: (https://saturn.jpl.nasa.gov/mission/top-tens/science-highlights/) -- Bill


Q:

Since a probe landed on Titan already, why are you sacrificing Cassini to avoid the near-zero chance of it crashing on another moon in the Saturn system?

A:

Huygens was specially designed (and cleaned) to enter and land on Titan. Cassini's maneuvering fuel is almost gone, and the Grand Finale is the most productive way to get new science and end the mission in a controlled manner. -- Doug I.


Q:

which moon is the most interesting? and why is it titan?

also any upcoming missions to the Saturn system after Cassini?

A:

You misspelled "Enceladus". ;-)

Titan and Enceladus are in my book the top two most interesting, but the enormous variety in moons is also incredibly interesting. We have moons that look like ravioli, like UFOs, like the Death Star, like a walnut, like a yin-yang symbol, like a loofah sponge, like an egg...oh yeah, and some that look a bit like our moon. How am I supposed to choose "most interesting"? :-)

No approved missions to Saturn yet, but maybe one of the proposals currently being reviewed will be the first to return. - Jo