Author Topic: AERCam Sprint  (Read 9872 times)

Offline copernicus

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AERCam Sprint
« on: 08/06/2006 05:09 am »
I wasn't sure where to put this as it applies to both Shuttle and ISS.  
I am refering to the AERCam Sprint concept.  It was flown successfully
on STS-97, but since has remained grounded.  

   It is a cheap, safe alernative to EVA when all one needs is
visual inspection of the exterior of a space craft.  
The AERCam Sprint is so cheap that it should have been flown
on every Shuttle mission since STS-97 to perform exterior
inspection of the Orbiter.  If this had happened, then the damage
to Columbia's left wing leading edge would have been easily detected.  

   My question is this - why isn't its latest version, the Mini-AERCam, being
flown NOW on every Shuttle mission?  Also, why aren't 5 or 6 of these
stationed at various locations on the Alpha ISS?  If one hears something
hitting the exterior of the ISS (remember this?), then one doesn't have
to wait days or weeks for an astronaut on an EVA to perform visual
inspection.

   Here is the link to the AERCam Sprint web site.

http://vesuvius.jsc.nasa.gov/er_er/html/sprint/index.htm




Offline Jim

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Re: AERCam Sprint
« Reply #1 on: 08/06/2006 08:40 am »
An EVA is required to deploy and retrieve the thing.  Also RF links may not work under the Orbiter.  To station them on the ISS, would require an EVA's to set up all the sites for the things, multiple RF links, etc.  How would they be reserviced, power and GN2?  It isn't just a simple task to add them.  There are also long duration exposure issues.


Offline DaveS

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Re: AERCam Sprint
« Reply #2 on: 08/06/2006 10:41 am »
Quote
Jim - 6/8/2006  10:27 AM

An EVA is required to deploy and retrieve the thing.  Also RF links may not work under the Orbiter.  To station them on the ISS, would require an EVA's to set up all the sites for the things, multiple RF links, etc.  How would they be reserviced, power and GN2?  It isn't just a simple task to add them.  There are also long duration exposure issues.

Also, the support equipment needed to operate it takes up alot of space. The RF transmitter took up one overhead window.

Also, what if this thing decides to malfunction and fly straight into the RCC panels during an inspection?

This is one of many things that the OBSS that makes it a superior choice over AERCam.
"For Sardines, space is no problem!"
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Offline PlanetStorm

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Re: AERCam Sprint
« Reply #3 on: 08/06/2006 05:21 pm »
Quote
DaveS - 6/8/2006  11:28 AM

Quote
Jim - 6/8/2006  10:27 AM

An EVA is required to deploy and retrieve the thing.  Also RF links may not work under the Orbiter.  To station them on the ISS, would require an EVA's to set up all the sites for the things, multiple RF links, etc.  How would they be reserviced, power and GN2?  It isn't just a simple task to add them.  There are also long duration exposure issues.

Also, the support equipment needed to operate it takes up alot of space. The RF transmitter took up one overhead window.

Also, what if this thing decides to malfunction and fly straight into the RCC panels during an inspection?

This is one of many things that the OBSS that makes it a superior choice over AERCam.

Would an accidental collision with an RCC panel really be a problem? The latest version of aercam has a mass of only 10 lbs ( http://www.nasa.gov/vision/space/workinginspace/aercam.html ), and it doesn't move very fast. Also, it's covered in soft bouncy material.  

In any case, the aercam would be a good choice choice for ISS inspections because it could get more or less everywhere. Also, if one was permanently on the ISS, the support equipment objection goes away.

Offline Jim

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Re: AERCam Sprint
« Reply #4 on: 08/06/2006 05:28 pm »
not true.  The support equipment would need to be delivered and installed and checkedout, therefor time, $ and upmass.  It would needs GN2 and electrical charging.

Offline psloss

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RE: AERCam Sprint
« Reply #5 on: 08/06/2006 05:32 pm »
Quote
copernicus - 6/8/2006  12:56 AM

I wasn't sure where to put this as it applies to both Shuttle and ISS.  
I am refering to the AERCam Sprint concept.  It was flown successfully
on STS-97, but since has remained grounded.
BTW, it was STS-87.

Offline PlanetStorm

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Re: AERCam Sprint
« Reply #6 on: 08/06/2006 05:33 pm »

Most of the $ and upmass would be a one-off though. Electrical charging is presumably available already on ISS, and GN2 usage must be very small, especially if you only fly it if you hear a bang.

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RE: AERCam Sprint
« Reply #7 on: 09/15/2006 09:37 pm »
MiniAERCam was basically cancelled after the first RTF mission, because - IMHO - the current shuttle inspection capabilities proved to be sufficient.

BTW, it was wonderful, but it wasn't that cheap.

Online Jorge

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RE: AERCam Sprint
« Reply #8 on: 09/16/2006 04:45 am »
Quote
copernicus - 5/8/2006  11:56 PM

I wasn't sure where to put this as it applies to both Shuttle and ISS.  
I am refering to the AERCam Sprint concept.  It was flown successfully
on STS-97, but since has remained grounded.  

   It is a cheap, safe alernative to EVA when all one needs is
visual inspection of the exterior of a space craft.  
The AERCam Sprint is so cheap that it should have been flown
on every Shuttle mission since STS-97 to perform exterior
inspection of the Orbiter.  If this had happened, then the damage
to Columbia's left wing leading edge would have been easily detected.  

   My question is this - why isn't its latest version, the Mini-AERCam, being
flown NOW on every Shuttle mission?  Also, why aren't 5 or 6 of these
stationed at various locations on the Alpha ISS?  If one hears something
hitting the exterior of the ISS (remember this?), then one doesn't have
to wait days or weeks for an astronaut on an EVA to perform visual
inspection.

   Here is the link to the AERCam Sprint web site.

http://vesuvius.jsc.nasa.gov/er_er/html/sprint/index.htm




It is important to distinguish between AERCam/SPRINT and Mini-AERCam. The former was unsuitable as a shuttle TPS inspection method, for several reasons. Some have been discussed here already but I'll summarize for completeness:

1) Requires EVA deploy/retrieve - not suitable for early (flight day 2) inspection
2) Must be hand-flown - no relative navigation capability in either translation or rotation
3) Limited delta-V capability due to non-refillable low-pressure GN2 RCS tanks
4) Resolution of existing cameras insufficient for detecting critical TPS damage
5) Insufficient comm resources on underside of vehicle

Mini-AERCam proposed to address these deficiencies:

1) Docking station in payload bay for deploy/retrieve without EVA
2) Relative GPS navigation, capability for orbiter-relative position and attitude control, pre-programmed autosequences for inspection
3) High-pressure Xenon RCS tank with recharge capability at the docking station
4) Integrated LDRI imaging system for inspection
5) Proposed tee-off of orbiter lower body antennas to improve comm and enable relative GPS

Mini-AERCam was evaluated along with numerous other TPS inspection options in mid-2003. It lost to the OBSS. There were several reasons, but two stuck out for me:

1) Mini-AERCam had a couple of cutting edge technologies that presented some cost and schedule risks. AERCam's relative GPS capability was unproven, some GPS experts were skeptical it could provide the required precision, and the AERCam development schedule was too compressed to allow much in-flight testing. On the other hand, OBSS is attached to the RMS - with knowledge of the RMS joint angles and the proper coordinate transformations, the precise location of the OBSS tip sensors can be known at all times. An OBSS scan can be halted at any time by putting the brakes on the arm, and paused for an arbitrary length of time, while AERCam would have to expend Xenon to stationkeep with the orbiter. And OBSS relied almost entirely on existing hardware, so it presented less cost and schedule risk.

2) TPS inspection without TPS repair is useless; all it does is tell you that you're going to die. OBSS offered a "growth path" to standalone TPS repair capability, while Mini-AERCam did not (and with the successful completion of the STS-121 OBSS Structural Dynamics DTOs, that growth path is looking pretty smooth now). So given that you're going to have to fly OBSS anyway for repair, why fly AERCam in addition? Is there anything AERCam can provide that OBSS can't, that justifies the mass hit and the development cost?

The answer is, of course, nothing.

Mini-AERCam made a brief comeback when it was discovered that some assembly flights had inadequate payload bay clearance for the OBSS. AERCam lost again when the shuttle program decided to develop - what else? - a mini-boom.

In the end, Mini-AERCam was a cool science project, and just out of respect for its sheer coolness I would like to have seen it developed. It still makes some sense to develop it for ISS, but the ISS program is fairly cash-constrained now and the coolness factor does not override that, unfortunately.
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Re: AERCam Sprint
« Reply #9 on: 09/18/2006 03:07 pm »
The LDRI capability was lost from Mini-AERCam, due to space limitations, I believe.  The last configuration contained two video cameras, but no lasers.  There is some talk about it re-emerging as a CEV accessory - surely there is some role for it as a handy way to do inspections outside a spacecraft.

Offline meiza

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Re: AERCam Sprint
« Reply #10 on: 09/18/2006 04:18 pm »
Can't one be tossed into the airlock and fly from there? No spacewalk required, and no outside "station" either. :)

Offline Jim

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Re: AERCam Sprint
« Reply #11 on: 09/18/2006 04:36 pm »
Quote
meiza - 18/9/2006  12:05 PM

Can't one be tossed into the airlock and fly from there? No spacewalk required, and no outside "station" either. :)

Who is going to open the outside hatch?

An astronaut who would have to be in a EVA suit and then could do the inspection himself?

Online Jorge

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Re: AERCam Sprint
« Reply #12 on: 09/18/2006 04:44 pm »
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bhankiii - 18/9/2006  9:54 AM

The LDRI capability was lost from Mini-AERCam, due to space limitations, I believe.  The last configuration contained two video cameras, but no lasers.  There is some talk about it re-emerging as a CEV accessory - surely there is some role for it as a handy way to do inspections outside a spacecraft.

Damn shame about losing LDRI. Oh well. It could be useful for Orion. I could see them deploying one from a SIM bay on the SM, like the P&F subsatellites on Apollo 15 and 16. But it won't be needed for Orion TPS inspection since the TPS will be completely covered by the SM until just prior to entry.

[edit - I just realized that Mini-AERCam's near-total reliance on relative GPS will make it pretty useless in lunar orbit, since it will be well above the GPS constellation...]
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Online Jorge

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Re: AERCam Sprint
« Reply #13 on: 09/18/2006 04:46 pm »
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meiza - 18/9/2006  11:05 AM

Can't one be tossed into the airlock and fly from there? No spacewalk required, and no outside "station" either. :)

Why would you need to? Mini-AERCam had the docking station in the payload bay, while AERCam/SPRINT was absolutely useless for inspection for the many other reasons I listed.
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Re: AERCam Sprint
« Reply #14 on: 09/18/2006 05:44 pm »
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Jorge - 18/9/2006  11:31 AM


[edit - I just realized that Mini-AERCam's near-total reliance on relative GPS will make it pretty useless in lunar orbit, since it will be well above the GPS constellation...]
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Surely some sort of GPS-like network will be put in lunar and Mars orbits.  I've heard of plans for the Mars network.   And I'm aware of one design for a personnel locating system for lunar base.

MiniAERCam can still be flown manually, though.  One of the cameras is specifically for navigation.   Maybe we need some kind of localized positioning system that could allow positioning relative to a spacecraft.

Offline hop

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Re: AERCam Sprint
« Reply #15 on: 09/18/2006 11:51 pm »
GPS like systems require a significant constellation, since you have to have multiple sats in view at any given time.  It's hard to imagine us putting constellations of 20+ satellites around the moon or Mars any time soon, especiallly given that GPS satellites are not particularly cheap or simple.

Long term lunar orbits are problematic because of mascons. See http://www.ias.ac.in/jessci/dec2005/ilc-7.pdf for example. For lunar orbit ops, I suppose you could put some transmitters on the ground instead. On the downside, they would be pretty useless for ground ops.

There have been suggestions of using existing GPS outside of LEO. Some informed discussion can be found here http://yarchive.net/space/spacecraft/gps.html

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Re: AERCam Sprint
« Reply #16 on: 09/19/2006 08:19 pm »
Today's "what is that debris floating around Atlantis?" problem would be a perfect mission for a Mini-AERCam...

Offline Jim

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Re: AERCam Sprint
« Reply #17 on: 09/19/2006 10:14 pm »
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bhankiii - 19/9/2006  4:06 PM

Today's "what is that debris floating around Atlantis?" problem would be a perfect mission for a Mini-AERCam...

No, it wouldn't because the debris had too high of velocity

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Re: AERCam Sprint
« Reply #18 on: 09/19/2006 11:50 pm »
I thought it was orbiting with the shuttle.

Online Jorge

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Re: AERCam Sprint
« Reply #19 on: 09/20/2006 05:53 am »
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bhankiii - 19/9/2006  3:06 PM

Today's "what is that debris floating around Atlantis?" problem would be a perfect mission for a Mini-AERCam...

As someone who has flown both AERCam/SPRINT (in a simulator) and Mini-AERCam (on an air-bearing floor), I would respectfully disagree.

Consider: the existing views of the "mystery objects" gave no clues as to their range. The first object was all of two pixels wide and out of focus. It could have been ten meters away or ten kilometers, and Mini-AERCam has no sensors to tell one way or the other. With no navaids on the object, the Mini-AERCam would have to be flown manually the entire way.

So you fly Mini-AERCam out of the bay to chase the mystery object. With no ranging sensors to guide you, you rely on the AERCam's forward navigation cameras. You line up on the object and thrust towards it until you can see the object getting bigger in the camera view.

Soon you start noticing the object drifting out of the center of the camera, and you thrust in that direction to try to match rates with it. But each time you re-center it, the object starts drifting again. Worse, you now notice the object is no longer getting bigger in the camera and every time you thrust toward it to try to re-establish a closing rate, it starts drifting off-center again, faster each time. Too late, you realize the object is farther away than it looked, and that you're fighting orbital mechanics trying to fly toward it. You're in the dreaded "McDivitt quadrant." Realizing that further approach is futile, you turn back toward the orbiter, now quite small in the distance. You've expended quite a bit of gas to get this far, but at least for the return trip you've got relative GPS so you can fly a more efficient approach. You've flown nearly to the limits of AERCam's tiny antennas, but hopefully the comm link will hold out long enough for you to get back. Hopefully.
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