STS-123 question

[Mark de Vries]

With space shuttle mission STS-123 set to launch on 11 March, I've been going over the schedule for the 16-day mission. There's one thing that I find a bit odd. On flight day 13, the shuttle's boom sensor system will be stored on the ISS. This boom is used to inspect the heat-resistant tiles on the underside of the shuttle before landing. The reason for storing it is to make room for more cargo on Eandeavour's next mission.
But all Endeavour will carry on that mission (STS-126 set for October) is a Multi-Purpose Logistics Module, which does not take up excess space in the payload bay, certainly not when compared to truss segments or lab modules, all of which were carried up with a boom system in the bay.
Who can shed a light on this?

 

[RyanLevy]

Clearly you've uncovered a cover-up, maybe they need the extra room for the alien spaceship they are returning! lol

 

[SeerSGB]

To make more room for special space-weed being grown on the ISS?

 

[RobertVA]

Maybe interference with a mounting bracket, save weight so additional consumables can be carried for a long duration mission or large number of planned EVA hours or to allow a few hundred more pounds of supplies to be carried to the ISS?

 

[JustAFriend]

Wellllll, since the sensor boom was carried up to inspect the orbiter,
and ALL of the final dozen flights are going to the ISS,
then why would they keep wasting fuel carrying it up on every flight???

Better to leave it on the ISS and just inspect the orbiters there....

 

[Mark de Vries]

Maybe interference with a mounting bracket, save weight so additional consumables can be carried for a long duration mission or large number of planned EVA hours or to allow a few hundred more pounds of supplies to be carried to the ISS?

But any extra supplies will be carried inside the MPLM, which fits just fine inside the payload bay, and I haven't found any references of there being a pallet with extra equipment on that mission.

Wellllll, since the sensor boom was carried up to inspect the orbiter,
and ALL of the final dozen flights are going to the ISS,
then why would they keep wasting fuel carrying it up on every flight???

Better to leave it on the ISS and just inspect the orbiters there....

You're essentially right, but the shuttle has at least two days of solo flight at the end of each mission - a period in which some damage to the tiles could conceivably occur. That's why a final inspection is usually done as late as the final flight day. With the sensor boom at the ISS, they couldn't do it like that anymore.

But some more thinking may have given me an answer. Perhaps they're leaving the sensor boom at the ISS not for Endeavour's next mission (the one with the MPLM), but for the mission immediately after STS-123? That one will be STS-124, flown by Discovery, and will carry up the pressurised module of the Japanese Experiment Module which is the single largest lab module of the station. Perhaps that is so big that there's no room for the sensor boom, which is why Discovery will have to use the boom that Endeavour left behind. At that point, Discovery's payload bay is of course empty again.

Slow day in the brain department for me, I suppose...

Or it's indeed to make room for that alien spaceship

 

[Paxil]

Wellllll, since the sensor boom was carried up to inspect the orbiter,
and ALL of the final dozen flights are going to the ISS,
then why would they keep wasting fuel carrying it up on every flight???

Better to leave it on the ISS and just inspect the orbiters there....

There is a Hubble repair mission scheduled this year.

 

[RobertVA]

Don't forget that the orbiters and many of the payloads carried into orbit were designed decades before the Challenger accident prompted the design and use of the inspection boom. The payload bays would have long established mounting points for the various equipment NASA was planning to carry aloft. Payload modules meant to be offloaded in orbit might require adapters containing the latch mechanisms meant to hold them in place until one of the Canada arms is ready to move them. There might be some cases where those modules need the attachment points used by the inspection boom's storage rack.

Also remember that much of the risk of thermal protection system damage is connected to foam shedding from the external tank. Any dangerous damage resulting from that would be subject to discovery during the pitch maneuver before ISS docking and an inspection with the boom's laser mapping system while docked to the station.

 

[Mark de Vries]

The inspection boom wasn't added until after the loss of Columbia.

There actually was a problem during the last mission, when the Columbus module took up too much space for the boom to be installed. They solved that by detaching the grappling fixture of the module (which the ISS Canadarm uses to grab hold of) and storing it separately.

The boom itself is stored in a similar position and opposite to the shuttle's Canadarm, on the periphery of the payload bay. It does not use any mounting point inside the bay, but is attached just below the payload bay door hinges. The only conflict would occur if something extends out of the bay and almost directly against the doors. That would've happen with Columbus's grapple fixture and could also be an issue with the pressurised module of Kibo.

I agree about the causes of damage to the heat tiles. All the same, there are always two inspections in a mission, just after launch and after undocking. There's always the risk of debris damage during the mission. During STS-115, Atlantis was hit by a micrometeoroid on one of her payload bays and debris was spotted near the orbiter before landing.

 

[Johnny Rico]

But some more thinking may have given me an answer. Perhaps they're leaving the sensor boom at the ISS not for Endeavour's next mission (the one with the MPLM), but for the mission immediately after STS-123? That one will be STS-124, flown by Discovery, and will carry up the pressurised module of the Japanese Experiment Module which is the single largest lab module of the station. Perhaps that is so big that there's no room for the sensor boom, which is why Discovery will have to use the boom that Endeavour left behind. At that point, Discovery's payload bay is of course empty again.

BINGO!!!

The reason why it's being left on station this time is because the next mission in May which brings up the ~35 foot Kibo module is so big that the OBSS won't fit in the cargo bay along with it.

So they're leaving it on orbit....there's only one of these things BTW (they use it on every mission regardless of which orbiter.) When Discovery comes up, it'll install Kibo, and then take back the OBSS from the station, and then do the normal inspection.

 

[Mark de Vries]

Space.com just gave the answer in this article...

Is there only one sensor boom? I seem to recall reading somewhere that after the loss of Columbia they cobbled two or three of them together out of Canadarm parts. Of course, I forget where I read that...

 

[Mark_Nguyen]

It's tough to say. All Canadarm and inspection segments are modular and interchangeable, and in fact this is done on a regular basis depending on maintenance schedules, replacement of broken components, etc. A segment of the inspection boom on one flight could be disassembled and fly as part of the actual Canadarm two flights later. Prior to Columbia, the Canadarm was only flown on flights that actually needed it for remote manipulation work; if they didn't it, they wouldn't fly with one. the arms are not assigned to any specific orbiter, but are swapped out and flown with different shuttles as they are needed and available.

As such, it's not accurate to say that Canada maintains two complete Canadarms and two inspection booms, inasmuch as they have the components to build up to two of them at a time. We know from recent evidence with Endeavour on the pad and Atlantis just returning that they have at least that many components, anyway. It's not like they were waiting for Atlantis to come back so they can pluck her OBSS out and slap it into her sister bird's cargo bay.

All the same, it's impractical to leave the OBSS on the station and do the inspections there. They need the time to analyze the tiles and the best time to do that is prior to docking; also, the arm was not designed to be left in space for extended amounts of time. In fact, they're installing special power hookups to maintain the arm in a "keep alive" mode so the mechanics and electronics inside don't succumb to the harsh environment of space.

Mark

 

[RobertVA]

Since the Columbus lab was loaded into the cargo bay on the pad (the video was shown on NASA's cable channel) I would think loading an arm while the shuttle is on the pad would be at least as easy.

 

[Mark_Nguyen]

I've no doubt they could - but there's no way NASA would nab any piece of hardware for re-use without testing and re-testing every bolt and wire for weeks on end.

Incidentally, ALL shuttle cargo is loaded at the pad - for the stuff in the cargo bay, it's wheeled out vertically and inserted into a special on-pad clean room before the Orbiter is rolled out. When the shuttle's in position, the payload is slotted in under clean conditions. As much as NASA could doubtless load and roll the shuttle and its cargo out to the pad in one go, they won't chance losing both en route in an accident.

And to answer the earlier question about the OBSS, the next shuttle mission launches not only the main Kibo module, but also the Japanese robot manipulator arm. Since the Kibo module fills up essentially the whole carbo bay (and is the only pressurized module to do so), the robot arm will be tucked in the same side space where the OBSS is carried. It's apparently easier to do this switching maneuver with the OBSS than to build a new way for the Japanese arm to go up on a separate flight, so that's what they're doing.

http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts123/index.html

Mark

 

[Johnny Rico]

I've no doubt they could - but there's no way NASA would nab any piece of hardware for re-use without testing and re-testing every bolt and wire for weeks on end.

Incidentally, ALL shuttle cargo is loaded at the pad - for the stuff in the cargo bay, it's wheeled out vertically and inserted into a special on-pad clean room before the Orbiter is rolled out. When the shuttle's in position, the payload is slotted in under clean conditions. As much as NASA could doubtless load and roll the shuttle and its cargo out to the pad in one go, they won't chance losing both en route in an accident.

And to answer the earlier question about the OBSS, the next shuttle mission launches not only the main Kibo module, but also the Japanese robot manipulator arm. Since the Kibo module fills up essentially the whole carbo bay (and is the only pressurized module to do so), the robot arm will be tucked in the same side space where the OBSS is carried. It's apparently easier to do this switching maneuver with the OBSS than to build a new way for the Japanese arm to go up on a separate flight, so that's what they're doing.

http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts123/index.html

Mark

Ahhh...good catch. I didn't realize that the Japanese arm was coming up with Kibo. I was figuring that it was coming up with the exposed facility.

 

[Mark de Vries]

Yes, of course, there's the Japanese arm as well. I'd forgotten about that.

Who knows where exactly on the ISS the sensor boom will be stored? I would imagine there's storage space on one of the truss segments.

 

[Mark_Nguyen]

It's stored along the truss, coaxially with it. There's plenty of space for attachment, and it won't block anything that they'll need to get at or work with for the duration it'll be there. The Truss was specifically built to support stuff like this, in addition to gas tanks, gyroscopes, antennas, spacewalking jazz, and of course the wiring and mechanics needed to make the solar arrays move.

Clicking on the STS-123 link above will let you find the mission press kit, which breaks down pretty much everything any news reporter would want to know about next week's flight, shuttle, cargo, and events. This is the same single document that pretty much every reporter who'll be narrating a segment on the mission will have at their side. You can bet that Miles O'Brien (CNN space commentator, not DS9 space engineer) has one when he's doing the commentary on the launch next week.

Plus, it has LOTS of pretty pictures.

Mark

 

[Johnny Rico]

Yeah, IIRC from the space walk mission pre-briefing, the OBSS will be stored on the S1 truss segment. And remember back during, or rather after, the STS-120 mission (Node 2) that the long amonia trays for Node 2 were stored on the aft side on the S0 truss.