Author Topic: Commercial Crew Schedule Analysis  (Read 114609 times)

Offline A_M_Swallow

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Re: Commercial Crew Schedule Analysis
« Reply #420 on: 10/09/2017 10:26 PM »
Yes and no. There are 6 months to fix the capsule. The parts sent up on a later mission. If the capsule cannot be repaired a replacement can be sent to the spacestation.

Considering that the probability of sustaining an MMOD strike is directly proportional to the time on orbit, it's more to the point that it's FAR more likely to sustain a strike while docked than during the relatively brief time between launch and docking.  Unless an approach inspection is going to reveal something that would rule out docking, it doesn't seem to add a lot of value.

The docking port could have been damaged. That may prevent docking.

A few more anti-satellite missile tests and the capsules may have to fly though a debris cloud.

An inspection of the outside of the capsule a couple of days before departure may be reassuring. Keeping the strike detection avionics and loss of pressure detectors operating whilst docked may be useful.

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I'm also struggling to think of any component that could be repaired on orbit in that timeframe.  Unlike station, the commercial crew vehicles are not being designed with on-orbit (EVA or EVR) repair in mind.

The Space Shuttles were not designed for on-orbit repair but a method of patching holes in the skin of Shuttles was devised. A similar patch may work with the airframe/skin and windows of capsules.

A strike on a capsule could damage one or more of the external solar panels, radiators, aerials, sensors, rocket nozzles, side of the docking port, windows or airframe. The aerials can probably be replaced.

edit:grammar + add nozzles
« Last Edit: 10/09/2017 10:36 PM by A_M_Swallow »

Offline SWGlassPit

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Re: Commercial Crew Schedule Analysis
« Reply #421 on: 10/12/2017 07:55 PM »
The docking port could have been damaged. That may prevent docking.

This is about the only really meaningful use case I can envision of a pre-docking inspection.  That said, the relatively small vulnerable area and the short exposure time makes this situation quite a bit more unlikely than other LOM scenarios.

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A few more anti-satellite missile tests and the capsules may have to fly though a debris cloud.

This is a red herring. Those debris clouds would have tracked objects in them.  If the rendezvous trajectory goes through a potential conjunction with a tracked object, the vehicle wouldn't be launched in the first place.

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An inspection of the outside of the capsule a couple of days before departure may be reassuring. Keeping the strike detection avionics and loss of pressure detectors operating whilst docked may be useful.

There are no strike detection avionics.  An inspection of the outside of the vehicle pre-departure would identify damage to reentry TPS that could wave-off undocking.

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The Space Shuttles were not designed for on-orbit repair but a method of patching holes in the skin of Shuttles was devised. A similar patch may work with the airframe/skin and windows of capsules.

These were ad hoc methods that are not easily transferred to new vehicle designs.  None of the new vehicles are designed to be EVA compatible.  There are no translation aids, and the TPS on the outer mold line likely would never be able to satisfy EVA kick load requirements.

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A strike on a capsule could damage one or more of the external solar panels, radiators, aerials, sensors, rocket nozzles, side of the docking port, windows or airframe. The aerials can probably be replaced.

All of these things are being analyzed on an ongoing basis and feed into the Loss of Crew/Loss of Mission numbers.  Many of these aren't as consequential as you imply, and on-orbit replacement isn't in the concept of operations.

Offline deruch

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Re: Commercial Crew Schedule Analysis
« Reply #422 on: 10/20/2017 04:57 AM »
SpaceX and Boeing Milestones from NAC yestesday. Taken from Eric Bergers twitter feed.

Full presentations from yesterday and today should be uploaded at below address within a few days:

https://www.nasa.gov/directorates/heo/nac-heoc
The link for the July 2017 NAC HEO meetings' Commercial Crew presentation is pointing to the wrong pdf.  I'm linking the correct slides found through some google-fu.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline woods170

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Re: Commercial Crew Schedule Analysis
« Reply #423 on: 11/16/2017 09:04 AM »
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Shotwell: still planning to carry out commercial crew test flights (uncrewed and crewed) in 2018.

https://twitter.com/jeff_foust/status/931088878395674624

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