Where did you hear 28 Discovery proposals? On Thursday Green said that he did not know how many they received. I heard Alfred McEwen say 28, but 28 was the number last year and I assumed that he made a mistake when he said that was the number for this year.
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: 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: 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: 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?
http://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9AEuropa Clipper Team Seeking Earlier Launch
BTW, I wish JUICE would end up orbiting Europa instead of doing multiple flybys. Technically it's possible; it wouldn't be harder IMHO than sending a spacecraft to orbit Mercury.
Quote from: baldusi on 02/21/2015 02:40 pm[...]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.SLS aside would all the others need gravity assists?
[...]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.
They clearly put a lot of thought into the solar arrays, and concluded it's worth the effort. I find it ironic that they might actually outlive the MMRTG power supply. I'm honestly surprised they proved lighter and more efficient to use than MMRTGs, but apparently the equipment and shielding for plutonium is heftier than even a large pair of wings. Otherwise the remaining concern is ensuring they don't affect the pointing for optical and infrared imaging.
Quote from: redliox on 02/24/2015 10:22 pmThey clearly put a lot of thought into the solar arrays, and concluded it's worth the effort. I find it ironic that they might actually outlive the MMRTG power supply. I'm honestly surprised they proved lighter and more efficient to use than MMRTGs, but apparently the equipment and shielding for plutonium is heftier than even a large pair of wings. Otherwise the remaining concern is ensuring they don't affect the pointing for optical and infrared imaging.I believe that one of the issues is that the MMRTGs have a faster power drop off rate than the older RTGs. Not quite sure why, but I can find out. The MMRTG was made to be more robust to survive landing on Mars. My guess would be that this includes more structure that cuts down on the heat transfer and thus the power drops off faster.
During the presentation they said that so far they have been testing spare solar cells from Juno. Those are not the most efficient arrays and the next phase of testing they want to do would be testing higher power arrays to see if they work as well.
MCR Findings (4 of 7)• A Class A risk classification for the mission may be overly constraining the system designs and trades, and not truly being applied consistently across the board, a Class B classification is recommended
Is there any appropriately certified, or even slightly bespoke Atlas V (e.g not a remix of Titan-Centaur),
Apologies, in the sense of tailored; but probably the fact that I could not compose it without bespoke or tailored is telling that any such LV is not really a plausible idea...
This makes me wonder if the Atlas V will also be affected by ULA's desire to phase into a NGLV as well as replacing the Russian engines. If so, this leaves Falcon (Heavy I presume) and SLS as the choice launchers.
Quote from: redliox on 03/04/2015 08:34 amThis makes me wonder if the Atlas V will also be affected by ULA's desire to phase into a NGLV as well as replacing the Russian engines. If so, this leaves Falcon (Heavy I presume) and SLS as the choice launchers.It isn't affected, Atlas V is a choice. Anyways, the ban was for military missions.