Cassini vs Curiosity - which is worth saving?

[Simon Ross]

EM-1 and EM-2 do. The rest are too far in advance for funding allocations right now to be meaningful.

And in 2 years time my friend, we will be sitting in this forum, bemoaning the cancellation of those two missions. SLS is a dead end.

[OrianCEV]

I think at that stage you might as well shut the manned mission section of NASA down and just give the budget directly to the Russians !

There simply wont be any future interplanetary manned missions. Personally I think the SLS is a bloody terrible idea, but it does happen to be the only chance NASA has to stay in the manned space flight business.

Why would NASA give all their funding to the RUSSIANS!!?They wouldn't do that...

[Edlu Kerman]

On 11/19/2013 at 11:20 AM, Requiem762 said:

Weapons of any kind in space could spark a new arms race and Cold War with other countries wanting to "close the nuclear moon bas gap."

Also, A moon colony with nukes would be violating a treaty 

On 11/24/2013 at 0:31 PM, minerman30 said:

This is actually a good idea. The plan goes as following:

NASA cancels Curiosity due to lack of funding

Public realizes how much we're underfunding NASA

Public elects officials who will fund NASA more

NASA continues all missions and launches new ones

[WISHFUL] 

[todofwar]

So what is the issue at hand here? Can't Curiosity chill out for a while until Cassini runs out of fuel for maneuvers and needs to be crashed? Once something is on target, especially a rover, what goes into maintenence from Earth? Midas can't upchare you that badly for a Martian oil change

[Nibb31]

There is no issue. If there was a budgetary choice to be made back in 2013, it has probably been made by now.

However, maintaining missions has a certain cost: you need to mobilize a very specialized and expensive workforce to run the mission and analyse the data, you need to maintain mission control facilities, and access to the DSN, which is also expensive. It's not so much a matter of budget as it is having several projects competing to use the same assets.

Edited July 6, 2016 by Nibb31

[todofwar]

6 hours ago, Nibb31 said:

There is no issue. If there was a budgetary choice to be made back in 2013, it has probably been made by now.

However, maintaining missions has a certain cost: you need to mobilize a very specialized and expensive workforce to run the mission and analyse the data, you need to maintain mission control facilities, and access to the DSN, which is also expensive. It's not so much a matter of budget as it is having several projects competing to use the same assets.

Right, so if they decide to stop funding Curiosity tomorrow, cant they reactivate it later? Granted, it won't last forever, but instead of simultaneously funding both why not do six month or three month shifts for each project?

I guess my question is, why does this have to be a final decision? Until we land a new rover or Curiosity breaks, why not just treat it as in storage if they can't fund it at the moment? People on this thread seem to be talking about it like they're planning on hitting the self destruct  (I know for Cassini they kind of are). I'm very much an amateur when it comes to this kind of thing so I'm happy to hear the reasons why.

[Nibb31]

38 minutes ago, todofwar said:

Right, so if they decide to stop funding Curiosity tomorrow, cant they reactivate it later? Granted, it won't last forever, but instead of simultaneously funding both why not do six month or three month shifts for each project?

Not really. The hardware is exposed to extreme condtions. The philosophy for this sort of mission is to maximize science returns as early as possible, because the older the hardware gets, the more chances you have of it failing.

 

38 minutes ago, todofwar said:

I guess my question is, why does this have to be a final decision?

Shutting down for 6 months means a 50/50 chance of it not waking up in 6 months, which would make it rather final. If it doesn't wake up, then you have wasted the opportunity to get from 1 to 6 months of science return on an expensive piece of hardware.

38 minutes ago, todofwar said:

Until we land a new rover or Curiosity breaks, why not just treat it as in storage if they can't fund it at the moment? People on this thread seem to be talking about it like they're planning on hitting the self destruct  (I know for Cassini they kind of are). I'm very much an amateur when it comes to this kind of thing so I'm happy to hear the reasons why.

As I said, it's not a decision any more. The thread is 3 years old and Cassini is ending in 2017.

[todofwar]

49 minutes ago, Nibb31 said:

Not really. The hardware is exposed to extreme condtions. The philosophy for this sort of mission is to maximize science returns as early as possible, because the older the hardware gets, the more chances you have of it failing.

 

Shutting down for 6 months means a 50/50 chance of it not waking up in 6 months, which would make it rather final. If it doesn't wake up, then you have wasted the opportunity to get from 1 to 6 months of science return on an expensive piece of hardware.

As I said, it's not a decision any more. The thread is 3 years old and Cassini is ending in 2017.

I thought I had read they had already planned out Cassini''s descent into Saturn. Of course, these kinds of decisions are going to come up again. I was always curious why funding continuing missions is an issue, God knows post docs and grad students aren't paid very much, I always figured you could at least hand the controls over to some academic lab for less than 500K a year in funding and they can squeeze some data out of it for a while. From what you say though I take it there are other factors at work for even controlling or accessing these probes beyond the manpower needed to run the probe itself. 

[Nibb31]

47 minutes ago, todofwar said:

I thought I had read they had already planned out Cassini''s descent into Saturn. Of course, these kinds of decisions are going to come up again. I was always curious why funding continuing missions is an issue, God knows post docs and grad students aren't paid very much, I always figured you could at least hand the controls over to some academic lab for less than 500K a year in funding and they can squeeze some data out of it for a while. From what you say though I take it there are other factors at work for even controlling or accessing these probes beyond the manpower needed to run the probe itself. 

Yes, most probes communicate through NASA's Deep Space Network, which is currently made of 3 stations (Goldstone US, Madrid Spain and Canberra Australia) and is shared by all the ongoing unmanned projects (including Cassini, various Mars missions, etc...). Each project is allocated slots for using the DSN, which vary depending on the bandwidth, the distance, and communication windows.

Each antenna can only communicate with one probe at a certain time, windows open and close as the Earth rotates, and the 70m et 34m antennas take a certain time to be pointed to a new target, so each project has to take turns when it comes to sharing the DSN assets. These stations also have downtime for maintenance, repairs (some of the antennas are quite old). The limitations of the DSN are one of the main bottlenecks for unmanned exploration projects, and one of the reasons legacy programs have to be cancelled to make room for new ones.

 

Edited July 6, 2016 by Nibb31

[SuperFastJellyfish]

Semi on topic:  DSN Now allows you to see what's talking to what station in real time.   

http://eyes.nasa.gov/dsn/dsn.html

[Nibb31]

5 minutes ago, SuperFastJellyfish said:

Semi on topic:  DSN Now allows you to see what's talking to what station in real time.   

http://eyes.nasa.gov/dsn/dsn.html

That's really cool. I didn't know of that website.

[ProtoJeb21]

I would like to save Cassini, but its mission is going to end next year. Like all good and costly NASA missions, Cassini is going to be vaporized. Wee! 

Now, I know that Cassini is running low on fuel and NASA doesn't want to contaminate Enceladus, but here's the thing: most of Saturn's interesting moons have very low gravity, and some of them don't have life. Why didn't NASA decide to land Cassini on one of the moons in Saturn's rings (Pandora, Prometheus, etc.) or on a dead major moon (Rhea, Dione, or Tethys)? It would take much less Delta-v to land on something like Tethys than to get Cassini into an eccentric polar orbit around Saturn. The moons need some love, too! 

But since Cassini is going to bite the dust (or gas, technically) with or without funding, I would decide to save Curiosity and extend its mission some more.

[PB666]

51 minutes ago, ProtoJeb21 said:

I would like to save Cassini, but its mission is going to end next year. Like all good and costly NASA missions, Cassini is going to be vaporized. Wee! 

Now, I know that Cassini is running low on fuel and NASA doesn't want to contaminate Enceladus, but here's the thing: most of Saturn's interesting moons have very low gravity, and some of them don't have life. Why didn't NASA decide to land Cassini on one of the moons in Saturn's rings (Pandora, Prometheus, etc.) or on a dead major moon (Rhea, Dione, or Tethys)? It would take much less Delta-v to land on something like Tethys than to get Cassini into an eccentric polar orbit around Saturn. The moons need some love, too! 

But since Cassini is going to bite the dust (or gas, technically) with or without funding, I would decide to save Curiosity and extend its mission some more.

Curiosity for sure. Cassini is the type of mission were you have batteries and fuel for a certain life and thats it, hey, time for replacement. NASA could do with more missions. I have no problem with a Cassini II.
But just before we go about pouting lets take a look at the legacy.

Asteroid 2685 Masursky fly-by (2000)
It also produced the most detailed global color portrait of Jupiter ever produced (seen on the right); the smallest visible features are approximately 60 km (37 mi) across.
The researchers observed a frequency shift in the radio waves to and from the space craft, as those signals traveled close to the Sun.
noted that mission scientists were puzzled by the fact that no "spokes" in Saturn's ring are visible.- A new, high-resolution picture of Saturn .(2004)
Cloud motion photos of saturn.
F-ring effector moons photographed.
Phoebe fly-by and characterization.
Cassini's first flyby of Titan
Discovery of two moons "Methone" (S/2004 S 1) and "Pallene" (S/2004 S 2)
Cassini's flyby of Iapetus
Huygens entered Titan's atmosphere at 09:06 UTC and had landed softly on its surface! (2005)
2 close fly-by's of enceladas.
reveals Enceladus has an atmosphere!
Radio occultation experiments on Saturn's Rings, to determine ring particle size distribution
Daphnis discovered.
closest flyby of Enceladus with a distance of 175 km
Flyby of Tethys at a distance of 1,500 km (930 mi).
Flyby of Hyperion at a distance of 1,010 km (630 mi)
Flyby of Dione at a distance of 500 km (310 mi).
Flyby of Rhea at a distance of 500 km (310 mi).
NASA confirms the presence of hydrocarbon lakes in Titan's northern polar region!
(2008) Scheduled missons complete.
Equinox-------------------
Cassini to directly sample Enceladus's cryovolcanic plumes!
radar coverage of Ontario Lacus, one of the largest methane lakes on Titan.
(2010) Equinox completed, technical faults occurred but were recoverable.
Solstice ------current mission--------
Just a whole bunch of fly-bys. (Tellene, Pallesto, Pandora, Pan, Atlas, Solstice, Aegeaon, Promethus, Epimetheus)

Thats kind of alot, it swooped within 25 km of some of those moons, one of the closest surviving fly-bys of any atmosphered moon. Its punched its antenna through saturns rings, sucked in volcanoe gas, buzzed moons, let's just say it a good lesson in living hard and dying in your prime. The kind of life that deserves an improved replacement mission by some mature space agency. 

 

 

 

 

 

 

 

[Nibb31]

1 hour ago, ProtoJeb21 said:

I would like to save Cassini, but its mission is going to end next year. Like all good and costly NASA missions, Cassini is going to be vaporized. Wee! 

Now, I know that Cassini is running low on fuel and NASA doesn't want to contaminate Enceladus, but here's the thing: most of Saturn's interesting moons have very low gravity, and some of them don't have life. Why didn't NASA decide to land Cassini on one of the moons in Saturn's rings (Pandora, Prometheus, etc.) or on a dead major moon (Rhea, Dione, or Tethys)? It would take much less Delta-v to land on something like Tethys than to get Cassini into an eccentric polar orbit around Saturn. The moons need some love, too! 

But since Cassini is going to bite the dust (or gas, technically) with or without funding, I would decide to save Curiosity and extend its mission some more.

It doesn't have enough thrust to land.

[peadar1987]

9 minutes ago, Nibb31 said:

It doesn't have enough thrust to land.

Cassini's main engines have a combined thrust of 890N. It has a dry mass of 2125kg. In theory is has enough thrust to land on any moon with a surface gravity of less than 0.04g. The only moon that actually rules out is Titan. The next highest gravity is Rhea at 0.027g. Of course, that's a pretty tight margin, and doesn't mean landing would be in any way practical, but you could probably manage it on one of the smaller moons. From a scientific point of view, the current "Grand Finale" plan makes a lot more sense as well. Cassini has no instruments that would be of any use, even if we could set it down on a moon.

[PB666]

21 minutes ago, peadar1987 said:

Cassini's main engines have a combined thrust of 890N. It has a dry mass of 2125kg. In theory is has enough thrust to land on any moon with a surface gravity of less than 0.04g. The only moon that actually rules out is Titan. The next highest gravity is Rhea at 0.027g. Of course, that's a pretty tight margin, and doesn't mean landing would be in any way practical, but you could probably manage it on one of the smaller moons. From a scientific point of view, the current "Grand Finale" plan makes a lot more sense as well. Cassini has no instruments that would be of any use, even if we could set it down on a moon.

Landing on a moon is exactly what they wanted to avoid, since the probe might carry contaminants, they could land on an atmosphereless moon thats about it. 

[ProtoJeb21]

57 minutes ago, peadar1987 said:

Cassini's main engines have a combined thrust of 890N. It has a dry mass of 2125kg. In theory is has enough thrust to land on any moon with a surface gravity of less than 0.04g. The only moon that actually rules out is Titan. The next highest gravity is Rhea at 0.027g. Of course, that's a pretty tight margin, and doesn't mean landing would be in any way practical, but you could probably manage it on one of the smaller moons. From a scientific point of view, the current "Grand Finale" plan makes a lot more sense as well. Cassini has no instruments that would be of any use, even if we could set it down on a moon.

Mimas should be the easiest major moon to reach, and it only has a gravitational pull of 0.00648g. As for instruments that could be useful, the cameras would be the best. I would like to do surface infrared and magnetospheric scans to see how Saturn's invisible forces are affecting this tiny moon. A lot more can be learned from the surface than from space.

34 minutes ago, PB666 said:

Landing on a moon is exactly what they wanted to avoid, since the probe might carry contaminants, they could land on an atmosphereless moon thats about it. 

Most of Saturn's moons don't have atmospheres, including a few of the major moons. These are Mimas, Tethys, and maybe Iapetus. All three would be great targets, especially Tethys with its low density. 

[PB666]

50 minutes ago, ProtoJeb21 said:

Mimas should be the easiest major moon to reach, and it only has a gravitational pull of 0.00648g. As for instruments that could be useful, the cameras would be the best. I would like to do surface infrared and magnetospheric scans to see how Saturn's invisible forces are affecting this tiny moon. A lot more can be learned from the surface than from space.

Most of Saturn's moons don't have atmospheres, including a few of the major moons. These are Mimas, Tethys, and maybe Iapetus. All three would be great targets, especially Tethys with its low density. 

Doen't it need a downward facing radio altimeter to land? Programmable to land?

[todofwar]

I doubt there's a major risk of contamination from cassini. I mean, what from Earth could live on Titan? If it's cold enough for liquid methane it's too cold for any water based life form. We use liquid ethane for rapid freeze quench to study reactive enzymatic species, a technique that gets its name from the fact that it pretty much halts all chemical reactions. Now, Enceladus is a different story I suppose, but the surface ice is presumably thick enough to keep out any contaminants as well. 

[PB666]

You mean a lander that goofs up and plunges into the  surface, scattering bits and pieces about a cold surface that can preserve microbes and cetain crustacoeans until the heat death of the universe.