Yes! We ARE going to Europa!

[Newt]

I am skeptical if you are suggesting it might change to a Europa Orbiter, LordFerret. Probably such a mission will be nuclear powered, and crashing such a vehicle on Europa, would be rather a difficult thing to allow. That is why they are doing flybys, though an orbiter would be preferable in almost every way.

[Kryten]

It not being an orbiter has nothing to do with power, it's about radiation and bandwidth issues.

[LordFerret]

I am skeptical if you are suggesting it might change to a Europa Orbiter, LordFerret. Probably such a mission will be nuclear powered, and crashing such a vehicle on Europa, would be rather a difficult thing to allow. That is why they are doing flybys, though an orbiter would be preferable in almost every way.

No, I was more referring to the number of fly-bys and distance in passing Europa... and of the instruments list (we'll have to see how the budget holds out). I highly doubt they've got the actual flight plan mapped out yet. Also, according to the article, the probe will be solar powered - not nuke powered, so why not smack it into Europa at the end of its mission such as Messenger did with Mercury.

Edited May 28, 2015 by LordFerret

[Nikolai]

why not smack it into Europa at the end of its mission such as Messenger did with Mercury.

Because if some of the speculations we have are correct and there is (a) a mechanism to transport surface minerals to the oceans below the ice, and ( life or proto-life in the oceans, then there is a chance (albeit a very slender one) that we could contaminate Europa with organisms strengthened by over three and a half billion years' worth of natural selection.

[cryogen]

Also the performance would be marginal for this application, it would likely require a third stage of some sort.

I did a bit of googling; I think you're right.

Here're the current figures for the Europa Clipper (although they're very likely to change). The total (wet) mass at launch is 3,582 kg (first link). The launch C₃'s, for the slow, gravity-assist Atlas V option, and the fast, direct SLS option, are 15 km²/s² and 82 km²/s² resp. (second link).

https://solarsystem.nasa.gov/europa/docs/Europa%20Clipper%20Info%20Sheet%2020130903.pdf

http://www.lpi.usra.edu/opag/jul2013/presentations/Clipper_Summary.pdf

Here's the C₃ curve for the Falcon 9 (I think this is v1.0? Not sure). Either way it's probably a non-starter; even the payload to C₃=0 (i.e. earth escape) is much less than the Clipper's mass.

http://www.spaceflightnow.com/falcon9/001/f9guide.pdf

What about Falcon Heavy? Well, it seems the specs haven't been published yet, so I did some extrapolating from some information that's already public. I used the marketing specs for the Falcon Heavy -- 21.2 tons to GTO, 13.2 tons to Mars Transfer. And I used specs from the Falcon 9 v1.1 upper stage, which I understand will be used unmodified (?) on the Falcon Heavy. (If there's a secret new stage under development, then this analysis is bunk). I used the vacuum I_sp and wet/dry masses for this upper stage.

http://www.spacex.com/falcon-heavy

http://www.spaceflight101.com/falcon-9-v11.html

Here's my extrapolation. Since the booster stages cut off well before GTO velocity, I'm assuming a fit of the rocket equation, to the GTO and Mars payloads, will roughly extrapolate the payload to higher C₃'s. There's tons of implicit assumptions here, too many to even discuss. This is a messy guesstimate at best.

I did a nonlinear fit in Mathematica, using these values:

[TABLE=width: 500]

[TR]

[TD]I_sp[/TD]

[TD]340 s[/TD]

[/TR]

[TR]

[TD]F9-H stage mass, dry[/TD]

[TD]3,900 kg[/TD]

[/TR]

[TR]

[TD]F9-H propellant mass[/TD]

[TD]92,670 kg[/TD]

[/TR]

[TR]

[TD]delta-v from LEO to GTO[/TD]

[TD]2.5 km/s[/TD]

[/TR]

[TR]

[TD]C₃ to Mars transfer[/TD]

[TD]10 km²/s²[/TD]

[/TR]

[TR]

[TD]F9-H payload to GTO[/TD]

[TD]21,200 kg[/TD]

[/TR]

[TR]

[TD]F9-H payload to Mars transfer[/TD]

[TD]13,200 kg[/TD]

[/TR]

[TR]

[TD]Effective perigee altitude for Oberth (guess)[/TD]

[TD]100 km?[/TD]

[/TR]

[/TABLE]

My estimate for F9-H's payload, for the SLS-direct trajectory, is 2,664 kg. This isn't very accurate at all, but it's much less than the Clipper mass (3,582 kg), so I think the conclusion is robust: F9-H can't do the direct Jupiter trajectory, with its current upper stage.

The VEEGA trajectory is easily an option. F9-H's payload would be slightly less than the Mars transfer -- 11,549 kg for C₃=15 km²/s².

update: On the other hand, a single Star-63F upper stage -- one of the larger solid rockets of the Payload Assist Module -- placed on top of the F9-H, could comfortably launch the Clipper on a Jupiter-direct trajectory. Take the Clipper mass (3,582 kg), add 10% margin (3,940 kg). Add on a 4,590 kg Star-63 F (total 8,530 kg). From my extrapolation, the F9-H could lift this much mass to C₃ = 30.2 km²/s². (This is a more comfortable estimate: it's very close to the Mars transfer that we have a datapoint for). Then the Star-63F can give us another 2,019 km/s boost, to a final C₃ of 84 km²/s².

I think that would be credible!

Star-63F specs:

[TABLE=width: 500]

[TR]

[TD]Isp[/TD]

[TD]297 s[/TD]

[/TR]

[TR]

[TD]empty mass[/TD]

[TD]326 kg[/TD]

[/TR]

[TR]

[TD]gross mass[/TD]

[TD]4,590 kg[/TD]

[/TR]

[/TABLE]

http://www.astronautix.com/engines/star63f.htm

https://en.wikipedia.org/wiki/Payload_Assist_Module

Edited May 28, 2015 by cryogen

[LordFerret]

Because if some of the speculations we have are correct and there is (a) a mechanism to transport surface minerals to the oceans below the ice, and ( life or proto-life in the oceans, then there is a chance (albeit a very slender one) that we could contaminate Europa with organisms strengthened by over three and a half billion years' worth of natural selection.

In that light, we've contaminated every body in this solar system we've visited/dropped a probe on thusfar. Europa will be no different, especially if they even remotely find an indication of life.

[Nikolai]

In that light, we've contaminated every body in this solar system we've visited/dropped a probe on thusfar.

Yes, and when the body is perceived to have a decent probability of hosting life, people can get quite upset. It's an active debate.

http://spectrum.ieee.org/aerospace/robotic-exploration/is-nasa-being-too-protective-of-mars

Not saying I know enough to know where I ought to land in this debate, mind. But it was one of the reasons cited as to why we deliberately crashed Galileo into Jupiter.

http://www.spaceref.com/news/viewnews.html?id=175

[cryogen]

update: On the other hand, a single Star-63F upper stage -- one of the larger solid rockets of the Payload Assist Module -- placed on top of the F9-H, could comfortably launch the Clipper on a Jupiter-direct trajectory. Take the Clipper mass (3,582 kg), add 10% margin (3,940 kg). Add on a 4,590 kg Star-63 F (total 8,530 kg). From my extrapolation, the F9-H could lift this much mass to C₃ = 30.2 km²/s². (This is a more comfortable estimate: it's very close to the Mars transfer that we have a datapoint for). Then the Star-63F can give us another 2,019 km/s boost, to a final C₃ of 84 km²/s².

I think that would be credible!

Small update, made a new C₃ chart:

[Kryten]

Are STAR-63s still available? I've not seen references to STARs past 48 in years.

[cryogen]

I wonder if they could use the tiny 2nd stage from Falcon 1e (Kestrel engine), and install it under the Falcon Heavy fairing (as a 3rd stage)? The rocket equation also closes for that..

http://www.spacelaunchreport.com/falcon.html

Are STAR-63s still available? I've not seen references to STARs past 48 in years.

Don't know. It's in ATK's catalog though.

Edited May 28, 2015 by cryogen

[Bill Phil]

Yes, and when the body is perceived to have a decent probability of hosting life, people can get quite upset. It's an active debate.

http://spectrum.ieee.org/aerospace/robotic-exploration/is-nasa-being-too-protective-of-mars

Not saying I know enough to know where I ought to land in this debate, mind. But it was one of the reasons cited as to why we deliberately crashed Galileo into Jupiter.

http://www.spaceref.com/news/viewnews.html?id=175

But people also complained about Galileo igniting Jupiter...

It's hard to avoid fire in the space biz.

[Kryten]

I wonder if they could use the tiny 2nd stage from Falcon 1e (Kestrel engine), and install it under the Falcon Heavy fairing (as a 3rd stage)? The rocket equation also closes for that..

It's doubtful the tooling still exists, SpX have firmly thrown their hat for cluster launches on F9 rather than dedicated launchers for small sats. All the customers who'd ordered 1e's were transferred to secondary slots on F9.

[windows_x_seven]

*gasp*

[LordFerret]

Yes, and when the body is perceived to have a decent probability of hosting life, people can get quite upset. It's an active debate.

http://spectrum.ieee.org/aerospace/robotic-exploration/is-nasa-being-too-protective-of-mars

Not saying I know enough to know where I ought to land in this debate, mind. But it was one of the reasons cited as to why we deliberately crashed Galileo into Jupiter.

http://www.spaceref.com/news/viewnews.html?id=175

Interesting articles. I've heard discussion regarding Galileo before, elsewhere. To take such precautions specifically, here, now, perhaps suggests they know/suspect more than they're telling... maybe?

[PakledHostage]

To take such precautions specifically, here, now, perhaps suggests they know/suspect more than they're telling... maybe?

Why is a simple abundance of scientific caution so often interpreted as a conspiracy? Planetary protection protocols and policies apply to all missions that we send out into the solar system.

[magnemoe]

In that light, we've contaminated every body in this solar system we've visited/dropped a probe on thusfar. Europa will be no different, especially if they even remotely find an indication of life.

Landers to Mars is sterilized, the one probe we sent into Jupiter orbit was put on an IO impact trajectory with it last fuel as it was not sterilized.

[Mr Shifty]

Not saying I know enough to know where I ought to land in this debate, mind. But it was one of the reasons cited as to why we deliberately crashed Galileo into Jupiter

And then we nonchalantly landed a hub-cap on Titan.

[Robotengineer]

IMO, the people who are worried about planetary contamination are overly protective.

[LordFerret]

Why is a simple abundance of scientific caution so often interpreted as a conspiracy? Planetary protection protocols and policies apply to all missions that we send out into the solar system.

Who said anything about a conspiracy? What I wrote was more intended a question than a statement. A question still unanswered.

And then we nonchalantly landed a hub-cap on Titan.

Excellent point.

[Kryten]

Who said anything about a conspiracy?

You did.

To take such precautions specifically, here, now, perhaps suggests they know/suspect more than they're telling... maybe?

The planetary protection standards for landers and orbital spacecraft are different, that's simply all there is to it.

[Hal]

And then we nonchalantly landed a hub-cap on Titan.

The thing is, while there might be some kind of life on Titan, it would have to be fundamentally different than Earth life, and much better adapted to its environment. Titan is so different from any part of Earth that contamination isn't really an issue. Europa or Mars, on the other hand, are problematic for precisely the reason we're so interested in them: they seem like they could possibly host Earth-like life. Because they're so similar (they have some kind of liquid water, or once did), we have to be more careful, as it's more possible that Earth life brought on our probes could actually survive and thrive there, possibly even outcompete whatever life is there.

At least this is what I think. I could be way off the mark.

[Robotengineer]

We worry about sending astronauts to Mars because of the radiation issues, but think that life could survive in the Jovian rad belts?

[Kryten]

We worry about sending astronauts to Mars because of the radiation issues, but think that life could survive in the Jovian rad belts?

I know you kids these days are out of touch with nature, so this might shock you, but there are actually organisms that are not humans.

[Robotengineer]

I know you kids these days are out of touch with nature, so this might shock you, but there are actually organisms that are not humans.

Do you have any example organisms that could survive that radiation?

[Mr Shifty]

We worry about sending astronauts to Mars because of the radiation issues, but think that life could survive in the Jovian rad belts?

Jupiter's radiation, like the Van Allen belts, is mostly charged particles, which wouldn't be able to penetrate a few centimeters, let alone the several kilometers of ice that Europa is encased in.

- - - Updated - - -

Do you have any example organisms that could survive that radiation?

http://en.wikipedia.org/wiki/Deinococcus_radiodurans