Should Cassini have landed on a Moon?

[todofwar]

On Thursday, July 07, 2016 at 9:04 PM, 55delta said:

Some

I hate to break it to some people, but NASA doesn't want any of their orbiter probes to land anywhere. 

Orbital probes don't go through nearly the decontamination process that they put landing probes through. Since it turns out that some bacteria can survive some incredibly harsh conditions. NASA doesn't want to find that they are later either accidently mucking up an environment or that they are re-discovering life from Earth. Since there are moons around Jupiter and Saturn that could have their own life, NASA doesn't want their orbital probes to crash or land on those moons, on purpose or on accident. That's why the Galileo probes was sent into Jupiter and why Cassini will be sent into Saturn.

Sorry, but it's for future science. But we are eagerly awaiting some of the planned landing missions that are in the works. 

I question how much of an issue this is. There's a difference between bacteria surviving and bacteria actually growing and multiplying. Nothing from Earth is going to propogate on any moon of Saturn with the possible exception of Enceladus. Granted, said bacteria will mean you can never trust what you see within a certain distance of your landing site, but it's not like we aim for the same region twice usually. Unless we need someone to be able to have a back up way to communicate after losing their antenna and getting impaled. 

[NovaSilisko]

On 7/7/2016 at 4:29 AM, Nibb31 said:

It's really annoying to see people on a game forum think they have it all figured out better than those stupide folks at NASA/JPL who have been studying projects like these for decades.

Yep, clearly the vast number of Cassini EOL options studied by JPL pale in comparison to what a few people on a forum have thought up...

I still wince in recollection of someone insisting that fixing Hubble was "easy" because you could "just send up a Soyuz" to fix it. KSP is the gateway for some into an understanding of spaceflight, and the gateway for others into a misunderstanding of it.

Edited July 9, 2016 by NovaSilisko

[Whirligig Girl]

2 minutes ago, NovaSilisko said:

I still wince in recollection of someone insisting that fixing Hubble was "easy" because you could "just send up a Soyuz" to fix it. KSP is the gateway for some into an understanding of spaceflight, and the gateway for others into a misunderstanding of it.

Relevant SMBC.

[ProtoJeb21]

The way I was thinking for Cassini to land on a moon like Janus or Pandora is a "sideways landing." Basically, the probe slows down in a sideways direction and has its camera turned towards the surface of the moon. Cassini will look for a shadow as it lands. When it gets closer, Cassini will do retrograde burns at a vertical angle, but will occasionally tilt sideways to see its shadow. This may or may not work.

Also, since landing on a Saturnian moon seems to be mostly impossible in this point in time, I've decided to change the topic of this thread to whether or not Cassini SHOULD'VE landed on a moon, not if it SHOULD.

[PB666]

39 minutes ago, ProtoJeb21 said:

The way I was thinking for Cassini to land on a moon like Janus or Pandora is a "sideways landing." Basically, the probe slows down in a sideways direction and has its camera turned towards the surface of the moon. Cassini will look for a shadow as it lands. When it gets closer, Cassini will do retrograde burns at a vertical angle, but will occasionally tilt sideways to see its shadow. This may or may not work.

Also, since landing on a Saturnian moon seems to be mostly impossible in this point in time, I've decided to change the topic of this thread to whether or not Cassini SHOULD'VE landed on a moon, not if it SHOULD.

No, it should go done with a blaze of firey glory into saturns atmosphere. 

[peadar1987]

1 hour ago, ProtoJeb21 said:

The way I was thinking for Cassini to land on a moon like Janus or Pandora is a "sideways landing." Basically, the probe slows down in a sideways direction and has its camera turned towards the surface of the moon. Cassini will look for a shadow as it lands. When it gets closer, Cassini will do retrograde burns at a vertical angle, but will occasionally tilt sideways to see its shadow. This may or may not work.

Also, since landing on a Saturnian moon seems to be mostly impossible in this point in time, I've decided to change the topic of this thread to whether or not Cassini SHOULD'VE landed on a moon, not if it SHOULD.

You'd have to have that fully automated because of the latency to earth though. I strongly doubt Cassini is capable of doing something like that on its own, no matter how much clever software we throw at it

[wumpus]

2 hours ago, NovaSilisko said:

Yep, clearly the vast number of Cassini EOL options studied by JPL pale in comparison to what a few people on a forum have thought up...

I still wince in recollection of someone insisting that fixing Hubble was "easy" because you could "just send up a Soyuz" to fix it. KSP is the gateway for some into an understanding of spaceflight, and the gateway for others into a misunderstanding of it.

I'm pretty sure the KSP would either fix that level of stupid (presumably ignorance, you can't fix stupid), or force a ragequit.  Although KSP does make inclination changes a bit too cheap, and a 3000m/s gravity well means an abundance of delta-v.  I wonder how long it takes before you realize "you can't get there from here".

[Bill Phil]

A part* of Cassini already landed on Titan, so...?

*yeah, it was Huygens. Still landed on Titan.

[kBob]

23 hours ago, todofwar said:

I question how much of an issue this is. There's a difference between bacteria surviving and bacteria actually growing and multiplying. Nothing from Earth is going to propogate on any moon of Saturn with the possible exception of Enceladus. Granted, said bacteria will mean you can never trust what you see within a certain distance of your landing site, but it's not like we aim for the same region twice usually. Unless we need someone to be able to have a back up way to communicate after losing their antenna and getting impaled. 

It's a remote possibility sure, but why take chances when there is really no need.  Leave landing to the probes designed for it (and as others have said they go through extra sterilization processed though even that isn't 100% sure).  I've seen this concern over on NASA's website somewhere I'm sure you can look it up.  But also consider if, on the way down, an unsterilized probe managed to send back some intriguing photos and you want to follow up with a future mission in that spot--you've already potentially contaminated the site.

Edited July 10, 2016 by kBob

[todofwar]

36 minutes ago, kBob said:

It's a remote possibility sure, but why take chances when there is really no need.  Leave landing to the probes designed for it (and as others have said they go through extra sterilization processed though even that isn't 100% sure).  I've seen this concern over on NASA's website somewhere I'm sure you can look it up.  But also consider if, on the way down, an unsterilized probe managed to send back some intriguing photos and you want to follow up with a future mission in that spot--you've already potentially contaminated the site.

I would say it's outright impossible. Too cold. If you have liquid methane, you can't have any bacteria grow, no chance. 

[PB666]

Because if the use a biological test for microbes one contanimant means microbes exist, and if you collide and unclean probe into a moon you could have billion floating around the surface, perfectly preserved in liquid methane. A nice wind blows, your filtration device collects it, you have an low quality off-site test that cant do DNA sequencing and essentually you are publishing an artifact. 

[moogoob]

On 7/9/2016 at 6:47 PM, Bill Phil said:

A part* of Cassini already landed on Titan, so...?

*yeah, it was Huygens. Still landed on Titan.

I was wondering about this - was Huygens put through the whole sterile decontamination process, but not Cassini?

[SyzygyΣE]

52 minutes ago, moogoob said:

I was wondering about this - was Huygens put through the whole sterile decontamination process, but not Cassini?

I don't think Cassini was put through the procedure. Perhaps, at Cassini's launch, they never intended for it to land so there was no worry about preventing Earth organisms getting on a celestial object. I mean, it doesn't really have any specialised equipment to land softly, I don't think. Sure, as you guys have been saying, it's possible, but it really depends on whether there can be significantly useful science, or a strong purpose for doing so. Again, NASA knows much more than we do, and the various options available and evaluated to them was not thought up over a period of time akin to the length this discussion has been active for. They will know what's best.

Jebediah would probably prefer the blaze of glory approach though. His only regret would be that he wouldn't be able to be there to watch the mighty spacecraft descend into the depends of the Saturnian atmosphere. 

Edited July 12, 2016 by SyzygyΣE

[YNM]

NASA considers all but two of the moons of Saturn are inhospitable. I'm not sure regarding Huygens back then, I hope ESA considered that Titan is of biological interest.

Edited July 13, 2016 by YNM
bit o' research

[Plusck]

Huygens and Cassini are enormously different spacecraft:

- 320 kg vs 2,150 kg,
- compact sturdy lander vs efficient orbiting broadcaster, power station and relay system

The challenges in cleaning the two craft sufficiently before launch, covering them up and then retesting them while making sure they don't carry contamination out of the atmosphere with them, are completely different.

In other words: sterilizing Huygens was relatively easy to do and was certainly done.
Keeping Cassini "launch-clean" would have been standard, but it would have been virtually impossible to sterilize.

On the plus side, as soon as we send a manned expedition anywhere, we can forget about trying to keep any subsequent probes squeaky clean.

[PB666]

3 hours ago, Plusck said:

Huygens and Cassini are enormously different spacecraft:

- 320 kg vs 2,150 kg,
- compact sturdy lander vs efficient orbiting broadcaster, power station and relay system

The challenges in cleaning the two craft sufficiently before launch, covering them up and then retesting them while making sure they don't carry contamination out of the atmosphere with them, are completely different.

In other words: sterilizing Huygens was relatively easy to do and was certainly done.
Keeping Cassini "launch-clean" would have been standard, but it would have been virtually impossible to sterilize.

On the plus side, as soon as we send a manned expedition anywhere, we can forget about trying to keep any subsequent probes squeaky clean.

Jupiter and Saturn are not in the near manned soace flight future. I think the big question is p(life) and you want your data points unequivicoble. Thats a more important because realistically manned missions into gravity well in deep gravity wells do really offer human anything other than burial plots. Our space goals should be to collect resources as as close to the interplanetary space-time thermodynamic potentials as possible