Falcon Heavy mission to Europa.

[Exoscientist]

 The Falcon Heavy has been awarded the Europa Clipper orbiter mission to Europa. It was calculated to take 6 years flight time using gravitational slingshots. However, actually it can be done in the same 3 years as by an SLS launch by using a high energy in-space stage such as the Centaur, no gravitational slingshots required.

 Moreover, it can even be a lander mission, not just orbital:

Low cost Europa lander missions. 

http://exoscientist.blogspot.com/2015/02/low-cost-europa-lander-missions.html 

 

   Robert Clark

[Mkisofsky]

Honestly, it strikes me as being odd that we are still doing deep space missions (well, the "deep space" part, anyway.  I don't see a practical way to get to LEO or higher without chemistry on some level) without some form of propulsion that doesn't involve chemistry.

I kinda liked the JIMO mission design (but abhorred the assembly plan), even though it was underpowered...  It would've paved the way for a lot better stuff, I think.

[tater]

On 7/27/2021 at 8:29 AM, Exoscientist said:

 The Falcon Heavy has been awarded the Europa Clipper orbiter mission to Europa. It was calculated to take 6 years flight time using gravitational slingshots. However, actually it can be done in the same 3 years as by an SLS launch by using a high energy in-space stage such as the Centaur, no gravitational slingshots required.

I suppose the questions are:

1. When would such a notional upper stage be available.

2. When would an SLS be available to put the stage in #1 on top of it.

3. Does this include the issues Europa Clipper has with the vibration environment WRT SLS (apparently it would add ~$1B to the spacecraft cost to deal with).

1+2 would be some number of years relative to when the EC spacecraft is ready to fly. If that number equals 3, the shorter flight time doesn't matter, both are 6 years, since FH is already good to go the day the spacecraft is ready. If 1+2>3, then the SLS launch actually takes longer to reach the target.

Also, WRT time, as soon as we are out more than a couple years into the future, SLS becomes completely obviated by Starship/Super Heavy. Musk has already said that an expendable upper stage is a possibility for outer solar system probes. A "starship" that is just a cylinder with a conventional fairing could be made of thinner steel (3mm or less vs 4mm), and be low enough mass that it can easily exceed SLS throw. A 16 dry upper stage (a 3mm SS tank section is ~16t) ) has 13.46km/s of dv with a 16.6t EC with lander. That leaves ~6km/s for the transfer, still low. 2mm steel adds about 1km/s.

#3 obviously adds cost, which might impact mission duration.

 

Regarding a lander, while that would be awesome, that's also a cost issue since presumably the lander is some hundreds of millions at the very least. Also, it looks like C3 for Europa limits EC to ~6t for SLS Block 1B, right? While a better upper stage can help, the same upper stage could be added as a third stage to SS/SH, and indeed a smaller once, since a stripped SS upper stage can do most of the work. Note that this assumes no refilling of the SS upper stage, if that capability exists at all... use SS, the tanks need not even be filled.

[tater]

What is the total spacecraft mass and dv?

An expended SH would likely add ~20% to the payload to LEO for SS/SH assuming it mirrors F9.

[wumpus]

12 hours ago, Mkisofsky said:

Honestly, it strikes me as being odd that we are still doing deep space missions (well, the "deep space" part, anyway.  I don't see a practical way to get to LEO or higher without chemistry on some level) without some form of propulsion that doesn't involve chemistry.

I kinda liked the JIMO mission design (but abhorred the assembly plan), even though it was underpowered...  It would've paved the way for a lot better stuff, I think.

Dawn was shot to escape velocity under chemistry even though she had 10km/s of non-chemistry delta-v.  Part of this might have been the issue of just how much time it takes (the team involved might want to have more papers in their entire career than the ones produced by Dawn), and some of it because it was untried tech (for NASA, there was a British experiment that went from LEO to the Moon  without chemistry).

I'm a huge fan of non-chemistry propulsion, and can't recommend chemistry for anything without a crew beyond LEO unless you have an unexpectedly shortened schedule (like a GPS satellite going out of commission and needing replacement immediately).  They also appear relegated to low-visibility NASA projects (granted, anything without a crew that isn't a huge telescope qualifies) as it doesn't fit in the "complete during the current president's available terms" timeline.

[Mkisofsky]

On 8/1/2021 at 4:49 AM, wumpus said:

Dawn was shot to escape velocity under chemistry even though she had 10km/s of non-chemistry delta-v.  Part of this might have been the issue of just how much time it takes (the team involved might want to have more papers in their entire career than the ones produced by Dawn), and some of it because it was untried tech (for NASA, there was a British experiment that went from LEO to the Moon  without chemistry).

I'm a huge fan of non-chemistry propulsion, and can't recommend chemistry for anything without a crew beyond LEO unless you have an unexpectedly shortened schedule (like a GPS satellite going out of commission and needing replacement immediately).  They also appear relegated to low-visibility NASA projects (granted, anything without a crew that isn't a huge telescope qualifies) as it doesn't fit in the "complete during the current president's available terms" timeline.

Yessir.  You and I are in complete alignment.  Dawn was amazing for what it was.  Most importantly, there was a tremendous amount of good science done, but, man, "pulling out' of orbit of one body and moving to orbit another one gave me chills.  This is, precisely, where we want to be.

But, "We need more power!" in the words of a fictional guy that I suspect that you know.

For now, I'm less concerned about getting to LEO with chemistry than I am just continuing the development of non-chemical propulsion beyond LEO, as it seems like you are as well, for tons of reasons, not the least of which is getting humans to interplanetary destinations before cosmic rays mess them up too much.  We'll solve the ground-to-LEO problem when we can, but if we can get enough stuff to LEO to enable manufacturing outside of the Earth's gravity well, we're in a different, and much better, zone, one where we can use chemistry just to fling the "meatware" to LEO, where they'll pick up heavy-ass "busses" wherever they need to go...