For Aron: Tell Me What it Means

>> Thursday, January 7, 2010

Aron asked: What does this mean? Orbiter: OV-105 / ET-134 / SRB BI-141 / RSRM 109 (VAB HB-1)

Let's break it down:

The first bit, OV-105, is the Orbiter Vehicle Designation, the one that tells us which Orbiter it is (as we still have three). In this case, OV-105 designates, for instance, Endeavour, the newest Orbiter, constructed as a replacement for Challenger in 1992. Only five space-worthy operational Orbiters were built: OV-099 (Challenger), OV-102 (Columbia), OV-103 (Discovery), OV-104 (Atlantis) and OV-105 (Endeavour). There were two other developmental prototypes: OV-098 (Pathfinder - a structural model) and OV-101 (Enterprise). Enterprise was designed to be the original Orbiter design, but without engines or heat shield; i.e. not spaceworthy. However, they did tests with Enterprise, including vibration tests, mated (to the Boeing) flight tests, and detached landing tests.

Why "Orbiter" and not "Shuttle" - well the part that comes back, the plane-like part, that lands some 4-24 days after launch is technically called an Orbiter in the Shuttle world. The whole system, Orbiter, External Tank, Solid Rocket Boosters, is called the Shuttle Transport System (hence the STS in the flight designation: STS-107, for instance). Just so you know

That leads us to the ET-134. That designates which External Tank it is. Each flight requires a new ET (they are not reusable and burn up in reentry). I think they are just numbered in order of construction, though they are not always flown in that order.

Similarly, I believe the SRB (which stands for Solid Rocket Booster) now called the RSRM for Reusable Solid Rocket Motor (also Redesigned Solid Rocket Motor) are just listed by number. I often hear the terms RSRM and SRB used interchangeably (even in technical circles), but, technically the RSRM is a redesign of the original SRBs. The SRBs/RSRMs have always been reusable and the cases are plucked from the drink not long after launch, refurbished, reloaded with solid rocket fuel and reshipped to KSC.

The last bit, I believe, has to do with where it sits in the Vertical Assembly Building (VAB), as in which High Bay (HB). But I'm speculating there.


  • Jeff King

    nice... i love to learn new things, thx for the question and the responce.

  • Aron Sora

    So the code gives everything in the system. Do you think those 4 missing external tanks where prototypes?

  • Stephanie B

    What four missing external tanks do you mean?

  • Phyl

    It's so interesting to find out little details like this! Thank you for the info.'s the big red tank that doesn't get recovered, and the two long, more slender ones that do, right?

  • Stephanie B

    Yes, Phyl. The external tank holds they cryogenic fuels for the Orbiters three main engines (hydrogen/oxygen) and is covered with an orange foam. The first few Shuttle flights, the ET was painted white over the foam, but they determined it served no purpose and added unnecessary weight so they stopped painting them.

    The tanks used today are actually third generation. There was the tank. Then the LWT or lightweight tank where they removed some supports and changed the materials of the attachment fittings (and removed a line they decided wasn't necessary). Now, they use exclusively SLWT or Super Lightweight Tanks, which have tanks of a different, lighter alloy and a few other changes. Half of the extra boost the Shuttles needed to get to the ISS is because of the weight reduction to the SLWT - but they're more expensive.

    STS-107, because it didn't need to go to the ISS, used the last LWT we've flown though there are one or two spares still around.

  • flit

    Question for you... Ross & I have been watching a lecture by Peter Diamondis ...about the X Prize stuff... how do you, as a safety geek, feel about the X Prize competitions as a way of pushing innovation?

    How are the safety issues handled...especially when it comes to space exploration, of course, and is it good enough?

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