Quote from: jongoff on 02/10/2015 03:46 amAfter some digging, it looks like the SLS missions were using ~85.4km^2/s^2, and both the Atlas V 551 and SLS Block I concepts had spacecraft masses around 5 metric tonnes. I'm going to run some numbers real quick.Ok, it looks like a refueled Centaur wouldn't cut it--I'm only getting 3600kg to a C3 of ~85-86km^2/s^2. But a refueled DCSS 5m stage looks like it would work--I'm getting ~4800kg to a C3 of 85-86km^2/s^2.So theoretically, in a magical world where depots exist instead of SLS Block I, you could do the direct to Europa injection using a refueled Delta-IV M+ (5,2) launch, with a lot of mass to spare, you wouldn't need a DIV-H. But you would need a well-stocked propellant depot--<cue vigorous handwaving>.As I said, it's a political non-starter, but I was morbidly curious from a technical standpoint.Spreadsheet I used (showing C3 vs payload for a refueled DCSS and a refueled Single-Engine Centaur) attached.
After some digging, it looks like the SLS missions were using ~85.4km^2/s^2, and both the Atlas V 551 and SLS Block I concepts had spacecraft masses around 5 metric tonnes. I'm going to run some numbers real quick.
One other thing: Falcon Heavy is not using cross-feed.... So you shouldn't use it in your calculations.
Back in October I had lunch sitting next to a guy from Aerojet who was working on an upper stage for (I think) Falcon Heavy to enable SpaceX to compete for the Solar Probe Plus mission. Dunno if that's gone public anywhere, but it may be mentioned elsewhere on this site. Anyway, they're locked out of a number of missions unless they upgrade their hardware....
http://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9AEuropa Clipper Team Seeking Earlier Launch
NASA has announced that they will be accepting instrument proposals.
Quote from: Blackstar on 02/20/2015 09:45 pmhttp://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9AEuropa Clipper Team Seeking Earlier LaunchSo I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?
Quote from: Zed_Noir on 02/21/2015 01:54 amQuote from: Blackstar on 02/20/2015 09:45 pmhttp://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9AEuropa Clipper Team Seeking Earlier LaunchSo I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?I suppose Falcon Heavy might still be too new a launcher to be entrusted with such an important mission, as I get the feeling that the dispensation that SLS gets on this wouldn't be applicable to another newish launcher. Especially as from what I have read on here they need to develop a high energy upper stage for it to be used on missions such as this.
Quote from: Star One on 02/21/2015 08:45 amQuote from: Zed_Noir on 02/21/2015 01:54 amQuote from: Blackstar on 02/20/2015 09:45 pmhttp://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9AEuropa Clipper Team Seeking Earlier LaunchSo I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?I suppose Falcon Heavy might still be too new a launcher to be entrusted with such an important mission, as I get the feeling that the dispensation that SLS gets on this wouldn't be applicable to another newish launcher. Especially as from what I have read on here they need to develop a high energy upper stage for it to be used on missions such as this.By 2022, even only flying a few times per year, falcon heavy will have ~20 flights under its belt. If they add a centaur/rl-10 based upper, the risk is in the integration and ground ops, not the upper stage itself. SLS has its own risk structure as well, and there are some planetary folks still sore about being politically married to a launcher.
Quote from: yokem55 on 02/21/2015 01:52 pmQuote from: Star One on 02/21/2015 08:45 amQuote from: Zed_Noir on 02/21/2015 01:54 amQuote from: Blackstar on 02/20/2015 09:45 pmhttp://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9AEuropa Clipper Team Seeking Earlier LaunchSo I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?I suppose Falcon Heavy might still be too new a launcher to be entrusted with such an important mission, as I get the feeling that the dispensation that SLS gets on this wouldn't be applicable to another newish launcher. Especially as from what I have read on here they need to develop a high energy upper stage for it to be used on missions such as this.By 2022, even only flying a few times per year, falcon heavy will have ~20 flights under its belt. If they add a centaur/rl-10 based upper, the risk is in the integration and ground ops, not the upper stage itself. SLS has its own risk structure as well, and there are some planetary folks still sore about being politically married to a launcher.You can't add that. The four options are:1) Atlas V 551 (gotta watch for replacement by NGLV)2) SLS3) Delta IV Heavy with kick stage (something like OrbitalATK's Star 48GXV)4) Falcon Heavy (non cross feed) with something like OrbitalATK's Star 48GXV or whatever Aerojet comes up with.
Quote from: ccdengr on 02/21/2015 03:26 amQuote from: Blackstar on 02/20/2015 05:53 pmNASA has announced that they will be accepting instrument proposals.In fact NASA had an AO last year for Europa instruments ( http://www.nasa.gov/press/2014/july/nasa-seeks-proposals-for-europa-mission-science-instruments/ ) and the selections are supposed to be announced in April -- though what the relationship between that AO and an actual flight project was never all that clear.Actually, now that I think about it, I may have mis-heard Jim Green yesterday. He may have said that the instrument selection is slipping from April to September. (I thought he was discussing the Discovery program, but I might have confused the two.)
Quote from: Blackstar on 02/20/2015 05:53 pmNASA has announced that they will be accepting instrument proposals.In fact NASA had an AO last year for Europa instruments ( http://www.nasa.gov/press/2014/july/nasa-seeks-proposals-for-europa-mission-science-instruments/ ) and the selections are supposed to be announced in April -- though what the relationship between that AO and an actual flight project was never all that clear.