What scenario are they planning for? Shuttle has the escape wires because there is no other method of escape. (At most times during the mission, your only hope to survive a Shuttle flight is to land safely.) Orion will have a good, old-fashioned escape rocket to pull the whole capsule into the sky and parachute down.
So you would use this roller-coaster to evacuate if the emergency is prior to the point where the access arm is retracted? I notice from the number of seats on the "coaster" that there are more than the Orion holds. For white-room launch pad workers, I guess?
Here is what is different from STS-107 and before:
* Many more cameras to monitor the ascent, including those cool views from the tops and bottoms of BOTH SRB's
* A new orbiter sensing boom with LASER cameras to get 3D images. Used at least twice every mission, day 2 and again two days before re-entry
* An extra back-flip maneuver during the ISS rendezvous for hi-res photos.
So as a result, they knew about this problem prior to landing which they WOULDN'T have on any mission before STS-107.
Also new:
* 3 different methods of tile repair if needed.
So now they take all of this and make a detailed engineering and risk analysis. What are we risking by landing as is? Computer model predicts that it is OK to land. Also, ACTUAL TILE is put into the arc-jet and tested in REAL REENTRY CONDITIONS to determine what happens if we leave it alone.
Oh, and don't forget they have the engineering expertise of 116 prior SUCCESSFUL Space Shuttle reentries and landings to draw from too, including a very similar tile damage event from STS-26.
Compare all of that to the VERY REAL RISK of causing WORSE damage by attempting the repair.
Their careful judgment: Leave it alone.
Is this a risk free decision? Nope - spaceflight is ALWAYS GOING TO BE A RISK. So everyone needs to get over that part. As long as they are making decisions on SCIENTIFIC and ENGINEERING grounds instead of the old Challenger/Columbia "well the o-ring/foam hasn't killed us before so it won't this time" mindset from before the accidents.
They did a good job here. Think it through and give them a break...
Oh, and as for the "why don't we get a new vehicle" posters - we are. Orion, 2014. Shuttle program over no later than October 1, 2010. Want it sooner? Give NASA MANY more billion dollars per year than we are now and they can get Orion going faster. Otherwise, here we are.
Shuttle has to worry about rain because, unlike the Russians, the shuttle heat shield is 1) exposed during the entire ascent instead of being tucked safely between rocket stages and 2) is made of silica glass that is glued on to the orbiter's belly. Rain=BAD
This latest thing just deepens my existing concern. 2010 is an ARTIFICIAL date set by the CAIB that NASA is treating like it came down from the mountain on stone. It takes X more shuttle flight to finish ISS plus one to fix Hubble one more time. As things stand with this mindset, X has to be achieved by the middle of 2010. A safety delay must not push it into 2011. No schedule pressure? Ha!! This artificial deadline INCREASES schedule pressure. So the next shuttle disaster is caused by schedule pressure in turn caused by one recommendation made by the board investigating the last one??
From the article: As a safety precaution, some experts are calling for 2004 MN4 to be "tagged" with a transponder that would constantly radio its position.
------------------
OK, but please proceed carefully. We wouldn't want to accidentally crash the transponder mission on the rock and effect the trajectory in an unpleasant way.:-)
Of course, if you can pull off a transponder rendevous, why not send a rocket motor instead and solve the problem? How much delta vee do you need to nudge a 1000ft rock into a safe trajectory?
1. I agree completely with keeping Hubble going until the Webb telescope is in place. Remember Shoemaker-Levy 9? We had telescopes and probes in the right place at the right time to capture a once-in-a-lifetime event that could not possibly be foreseen. We need to maintain the capability. We have no idea what we might miss if we don't.
2. We are not talking about changing a plan here. The servicing mission was always part of the plan. But Columbia made O'Keefe gutless. That fact is that it will be NO MORE DANGEROUS to go to Hubble with a crew now than it was all the previous times. In fact, it will be LESS dangerous since they will be operating post-CAIB with a can of Thermal Tile Fix-a-Flat in the glove box and a rescue shuttle on pad 39B.
Slashdot Mirror
What scenario are they planning for? Shuttle has the escape wires because there is no other method of escape. (At most times during the mission, your only hope to survive a Shuttle flight is to land safely.) Orion will have a good, old-fashioned escape rocket to pull the whole capsule into the sky and parachute down. So you would use this roller-coaster to evacuate if the emergency is prior to the point where the access arm is retracted? I notice from the number of seats on the "coaster" that there are more than the Orion holds. For white-room launch pad workers, I guess?
Here is what is different from STS-107 and before:
* Many more cameras to monitor the ascent, including those cool views from the tops and bottoms of BOTH SRB's
* A new orbiter sensing boom with LASER cameras to get 3D images. Used at least twice every mission, day 2 and again two days before re-entry
* An extra back-flip maneuver during the ISS rendezvous for hi-res photos.
So as a result, they knew about this problem prior to landing which they WOULDN'T have on any mission before STS-107.
Also new:
* 3 different methods of tile repair if needed.
So now they take all of this and make a detailed engineering and risk analysis. What are we risking by landing as is? Computer model predicts that it is OK to land. Also, ACTUAL TILE is put into the arc-jet and tested in REAL REENTRY CONDITIONS to determine what happens if we leave it alone.
Oh, and don't forget they have the engineering expertise of 116 prior SUCCESSFUL Space Shuttle reentries and landings to draw from too, including a very similar tile damage event from STS-26.
Compare all of that to the VERY REAL RISK of causing WORSE damage by attempting the repair.
Their careful judgment: Leave it alone.
Is this a risk free decision? Nope - spaceflight is ALWAYS GOING TO BE A RISK. So everyone needs to get over that part. As long as they are making decisions on SCIENTIFIC and ENGINEERING grounds instead of the old Challenger/Columbia "well the o-ring/foam hasn't killed us before so it won't this time" mindset from before the accidents.
They did a good job here. Think it through and give them a break...
Oh, and as for the "why don't we get a new vehicle" posters - we are. Orion, 2014. Shuttle program over no later than October 1, 2010. Want it sooner? Give NASA MANY more billion dollars per year than we are now and they can get Orion going faster. Otherwise, here we are.
Shuttle has to worry about rain because, unlike the Russians, the shuttle heat shield is 1) exposed during the entire ascent instead of being tucked safely between rocket stages and 2) is made of silica glass that is glued on to the orbiter's belly. Rain=BAD
This latest thing just deepens my existing concern. 2010 is an ARTIFICIAL date set by the CAIB that NASA is treating like it came down from the mountain on stone. It takes X more shuttle flight to finish ISS plus one to fix Hubble one more time. As things stand with this mindset, X has to be achieved by the middle of 2010. A safety delay must not push it into 2011. No schedule pressure? Ha!! This artificial deadline INCREASES schedule pressure. So the next shuttle disaster is caused by schedule pressure in turn caused by one recommendation made by the board investigating the last one??
From the article: As a safety precaution, some experts are calling for 2004 MN4 to be "tagged" with a transponder that would constantly radio its position.
:-)
------------------
OK, but please proceed carefully. We wouldn't want to accidentally crash the transponder mission on the rock and effect the trajectory in an unpleasant way.
Of course, if you can pull off a transponder rendevous, why not send a rocket motor instead and solve the problem? How much delta vee do you need to nudge a 1000ft rock into a safe trajectory?
1. I agree completely with keeping Hubble going until the Webb telescope is in place. Remember Shoemaker-Levy 9? We had telescopes and probes in the right place at the right time to capture a once-in-a-lifetime event that could not possibly be foreseen. We need to maintain the capability. We have no idea what we might miss if we don't.
2. We are not talking about changing a plan here. The servicing mission was always part of the plan. But Columbia made O'Keefe gutless. That fact is that it will be NO MORE DANGEROUS to go to Hubble with a crew now than it was all the previous times. In fact, it will be LESS dangerous since they will be operating post-CAIB with a can of Thermal Tile Fix-a-Flat in the glove box and a rescue shuttle on pad 39B.