ATV Q&A

• ATV Q&A by Danderman on 06 Dec, 2009 15:15
• Forgetting ISS reboost requirements for a moment, it occurs to me that the Ariane launcher used for ATV may be over engineered, in the sense that the upper stage may not be necessary; ATV may be able to boost itself into the proper orbit without the need for the upper stage, by using its very large propellant supply, much as Shuttle does today. Ariane, without the upper stage, should be able to inject ATV into an orbit with a low perigee, allowing ATV to simply raise the perigee.
  
  Again, this  configuration would cost a significant amount of ATV prop, but my understanding is that ATV does not utilize much prop at ISS anyways.
  
• #1 by Ben the Space Brit on 07 Dec, 2009 09:40
• I don't know but I presume most of the upper stage power is used to get lots of cargo up to a stable initial LEO. 
  
  That said, and this deserves to be repeated, that Ariane-5 was originally designed to launch a crewed space 'plane.  Most of its design and capabilities are informed by that original purpose. 
  
  Now, an ATV question of my own... although it could also be considered an Ariane-5 question.  I hypothetically have an ATV that I want to send to resupply a crewed space laboratory in either the EML-1 or EML-2 halo orbit.  Can Ariane-5 do it as-is or will there need to be modifications? If so, what modifications are required?
  
  I ask this question because one post-ISS 'plan-B' is for ESA to launch a twin-module ATV-derived lab, probably to LEO, as an interim destination.  It occured to me that a similar vehicle sent to one of the EML points would do nicely as an initial place to go in the event of a 'flexible path' program strategy.
• #2 by sdsds on 07 Dec, 2009 16:31
• Quote from: Ben the Space Brit on 07 Dec, 2009 09:40

  I don't know but I presume most of the upper stage power is used to get lots of cargo up to a stable initial LEO. 
  
  That said, and this deserves to be repeated, that Ariane-5 was originally designed to launch a crewed space 'plane.  Most of its design and capabilities are informed by that original purpose. 
  
  Now, an ATV question of my own... although it could also be considered an Ariane-5 question.  I hypothetically have an ATV that I want to send to resupply a crewed space laboratory in either the EML-1 or EML-2 halo orbit.  Can Ariane-5 do it as-is or will there need to be modifications? If so, what modifications are required?
  
  I ask this question because one post-ISS 'plan-B' is for ESA to launch a twin-module ATV-derived lab, probably to LEO, as an interim destination.  It occured to me that a similar vehicle sent to one of the EML points would do nicely as an initial place to go in the event of a 'flexible path' program strategy.
  

  
  The ATV concept of operations is really good.  (ESA has a lovely animation available at the bottom of http://www.esa.int/SPECIALS/ATV/SEM7S1L26DF_0.html that shows it quite nicely.)  Underlying the operations concept is a subtly elegant architecture for exploration.
  
  It starts with Ariane, a launch system that justifies its own existence with its utility for non-exploration missions.  Even though the ATV launcher has its own designation (Ariane V ES) and is a configuration slightly different than either the ECA or GS variants, it uses pretty much "stock" parts.  That has to make it incredibly cost effective as a booster for exploration!
  
  Could it get to an ATV to an EML point?  The ES can take 21 mT to LEO, and a loaded ATV uses pretty much all of that capability.  For ATV as an ISS resupply vehicle, 8 of the 21 mT is considered payload.  But what if that 8 mT were all propellant for a trip to an EML point?  Would a hypergolic engine have the Isp to provide the needed delta-v?  Would an ion thruster? 
  
  I'm betting the answers are that a hypergolic engine with an Isp in the 300 range would not, but an ion thruster with an Isp in the 3000 range would. 
  
  What does the rocket equation say?
  
  9.8 * 3 000 * ln(21 / (21 - 8 )) = 14 099.4486
  
  Yes, an ion thruster could do the job with lots of margin.
  
  Is there any quicker way?  A powered lunar swing-by can get you from LEO to EML2 in 23 days with a delta-v budget of 3522 m/s.
  
  3 522 / (9.8 * ln(21 / (21 - 8 ))) = 749.39101
  
  No conventional engine is going to have an Isp anywhere near 750.   So the question becomes, "Is a really slow trip to an EML point powered by an ion thruster OK?"
• #3 by whitewatcher on 21 Dec, 2009 13:43
• Quote from: Ben the Space Brit on 07 Dec, 2009 09:40

  I hypothetically have an ATV that I want to send to resupply a crewed space laboratory in either the EML-1 or EML-2 halo orbit.  Can Ariane-5 do it as-is or will there need to be modifications? If so, what modifications are required?

  
  You can't do that with chemical propulsion unless you dock ATV to a fuel container in LEO. But this would be a 2-launch-architecture which is considered to be impractical and dangerous.
  
  Risky mission phases are:
  1. Launch
  2. Atmospheric Entry
  3. Docking
  4. All the other things.
  
  One could add an electric thruster,yes.
  Hypothetically you could use the "hole" in the rear section to place the  thruster there. But you still need an energy source. The solar panels have some margin, but not enough for going beyond LEO. Nuclear sources are not an option.
  To cut the story short: You need substantial redesign to power generation and distribution as well as to tubing and fuel management. Nobody want's to touch the existing design, because the machine is so complicated, has been developed in Toulouse and is now built in Bremen. (original designers are in Toulouse and have closed the project on their side)
  
  I have asked your questions to one of my colleagues half a year ago.
• #4 by TJL on 06 Feb, 2011 13:46
• Is the ES version of the Ariane 5 only used for launching ATV?
  Any plans to use it for other spacecraft?
  Thank you.
• #5 by Stephan on 06 Feb, 2011 15:36
• For the moment, yes, it's only used for ATV.
  It was considered for Galileo constellation but only Soyouz rocket were procured for the moment.
• #6 by mmeijeri on 06 Feb, 2011 15:46
• At the moment the ES is the only variant with a restartable upper stage. That will change once Vinci and ESC-B are operational, but nobody knows when that will be as it depends on available funds.
• #7 by Nicolas PILLET on 12 Apr, 2012 14:43
• I've just learnt that RKK Energiya inernally calls ATV "398ГК"...
• #8 by baldusi on 14 Apr, 2012 05:01
• I've read that the ATV line has been closed down, in part due to parts obsolescence. Yet, the ATV is a relatively modern development, and I thought the usual lifetime of parts was around 30 years, not ten. Or did the started development with "old" parts?
• #9 by mtakala24 on 14 Apr, 2012 09:59
• No, but as the production line for these custom made space-rated systems has been shut down, it would need a lot of lead time to acquire new subsystem assemblies, even if the individual components are still available.
  
  
• #10 by mdmcgrory on 06 Jun, 2012 07:37
• So that's it than? ESA is done with it's contribution to the ISS after ATV 5?  Or ATV 4?
• #11 by Space Pete on 06 Jun, 2012 11:55
• Quote from: mdmcgrory on 06 Jun, 2012 07:37

  So that's it than? ESA is done with it's contribution to the ISS after ATV 5?  Or ATV 4?
  

  
  ATV-5 will be the last ATV, however that doesn't mean ESA is done with its contribution to ISS - if they want to stay in the program in the 2015-2020 timeframe (and they have already confirmed that they do), then they'll need to pay their dues somehow - if not with ATVs, then with something else (likely some kind of ATV derivative vehicle).