Comments on: Shuttle safety dance

By: don

don — Thu, 16 Apr 2009 15:57:16 +0000

@ Peter B
Your thoughts are correct. They only need the backup shuttle for Hubble missions when getting to the ISS is impossible with the current design limitations (not enough fuel for orbit changes necessary to get to ISS). Since there won’t be any more Hubble missions after this one, there won’t be another need for 2 shuttles to be launch ready at the same time. (At least with the current planning – who knows if they will extend the life of the shuttle while waiting for Constellation/Aries to become available. They did extend the life of the shuttle by 1 extra mission. Maybe more will be added since politically it’s not a popular idea that the US won’t have human launch capability for several years, but there’s also pressure to terminate the shuttle program as quickly as possible. That’s a whole debate unto itself.)

Missions to ISS could theoretically extend their stay for up to several additional weeks (longer with Soyuz/Progress resupply missions) – hopefully enough time for another shuttle to be prepared and sent for rescue. So at the moment, there isn’t a need for a backup shuttle to be launch ready at the same time.

By: Peter B

Peter B — Thu, 16 Apr 2009 15:41:49 +0000

Christopher A. Eirich asked: “Can somebody please elaborate further as to why we’ll never see 2 shuttles positioned for launch at the same time ever again? Phil wasn’t clear about this in his article, and I’d like to know…”

I assume it’s because there won’t be any more Hubble service missions performed by the Shuttles before they’re retired. All other Shuttle missions will be to the ISS, and if something goes wrong on such a mission, the Shuttle can simply remain with the ISS, so having a second Shuttle on standby isn’t necessary.

By: Christopher A. Eirich

Christopher A. Eirich — Wed, 15 Apr 2009 22:16:42 +0000

Can somebody please elaborate further as to why we’ll never see 2 shuttles positioned for launch at the same time ever again? Phil wasn’t clear about this in his article, and I’d like to know….

By: Johnny Vector

Johnny Vector — Wed, 15 Apr 2009 12:47:16 +0000

Gopher65, you do not recall correctly. The old external tanks are all gone; new ones have been manufactured in the last year or two at the Michoud facility in Louisiana. They are filled just before launch because loading and unloading fuel is not without risk, so you want to make sure as many things are working as possible before you fuel.

Darrin, you may have Safety Dance in your head, but I have YMCA:
http://www.kevland.com/blog/2008/09/ayyy-ceee-esss-arrr/

By: Alex

Alex — Wed, 15 Apr 2009 01:38:38 +0000

JB: Bringing back a failed commsat simply isn’t economic.

Firstly the costs of refurbishing the bird are a high percentage of building a new one from scratch. Unlike your car, which is designed to be repaired in it’s lifetime, the bird is designed to be launched once. So you have to work out how to safely discharge the fuel, disassemble, diagnose & repair damage, rebuild and then refuel. Then at the end of the process you’ve got a bird which cannot be considered new, and probably will have to be sold at a discount to a less well off customer who can’t afford the full price.

Secondly, you have to consider the costs of bringing the bird back. At the very minimum you’ve got to launch a very heavy vehicle to enclose the bird. That means a lot of fuel. It’s also only been shown to be possible when the bird was originally launched by the shuttle, it’s still controllable (to bring it back into an orbit where it can be grabbed) and by using highly trained humans using specially designed tools which are unique for each design of bird, and at high risks to themselves.

The economically sensible route is to launch satellites using cheap expendable rockets such as Ariane, Delta or Titan, and if they fail, then shrug, learn why it failed if we can, and rebuild them.

By: Paul M.

Paul M. — Wed, 15 Apr 2009 01:01:22 +0000

Good work with the lyrics there Darrin… I take my hat off to you!

By: Steve A

Steve A — Tue, 14 Apr 2009 22:39:52 +0000

@ Juergen, tony tony tony

If this was happening a few years ago, they probably wouldn’t need to move it. However, pad 39B is now undergoing modifications so it can become a launch pad for the Constellation program. Right now, work is being done so the Ares I-X test rocket can launch from there this summer. Already, they have erected giant lightning towers to protect the rocket. I’m not sure how far along it is, but the plan is also to add an abort system so when astronauts are in the craft, they escape quickly if there is a problem

BTW, the Constellation architecture should be able to service the Hubble if necessary. In this case, service probably means intentionally deorbiting it when the time comes in order to plan where exactly it will land on Earth. IIRC, one of the tasks on the Hubble repair mission is to add attachments so Orion could grab it and place it in a planned orbit when the time come. I’m not sure if this is still happening.