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Fraser
2007-Aug-21, 04:08 PM
After 13 days in space, the space shuttle Endeavour touched down safely in Florida today. NASA managers actually decided to bring the shuttle home a day early, to beat Hurricane Dean, currently ravaging the East Coast of Mexico. ...

Read the full blog entry (http://www.universetoday.com/2007/08/21/sts-118-endeavour-touches-down-safely-in-florida/)

Cassiopeia
2007-Aug-22, 07:13 AM
Hi folks,

I was wondering if the tanks are emptied in space for saftey reasons in space right before reentry.
If they don't then I do not understand why they are coming down in a serpentinelike path. Or are the engines only able to operate at full throttle and this would be to difficult to steer? :confused:

Cheers.

Didi

thothicabob
2007-Aug-22, 08:03 AM
once they enter the atmoshere, i don't believe they use the engines. the serpentine track is to scrub off speed, i think, so they can avoid a supersonic landing. ;o)

i'm kind of curious to know if the micrometeroid damage to the windscreen was worsened at all duing re-entry...

AstroDuck
2007-Aug-22, 01:34 PM
I believe the reason for the early return (at the time of the decision to return early) was that Hurricane Dean had (at that time) the potential to turn north and impact operations at Mission Control at Johnson Space Center in Houston, TX and force a possible evacuation there. I don't think there was any consideration of the hurricane having any potential of impacting operations at the Kennedy Space Center.

Hamlet
2007-Aug-22, 07:14 PM
Hi folks,

I was wondering if the tanks are emptied in space for saftey reasons in space right before reentry.
If they don't then I do not understand why they are coming down in a serpentinelike path. Or are the engines only able to operate at full throttle and this would be to difficult to steer? :confused:

Cheers.

Didi

The shuttle is basically a glider during its return to Earth. It is not using its engines. The reason for the serpentine track is to bleed off orbital energy before reaching its landing site. These "S-turns" increase the length of the track from entry interface to landing and allow the shuttle to shed speed and keep the thermal load within the required limits.

The shuttle has to go from about 17,000 mph in orbit to about 280 mph at landing. These turns help manage that deceleration.

Here is good reference for the Entry Phase (http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_mes.html#mes_entry) of the shuttle.

Dave J
2007-Aug-23, 02:28 AM
There are many tanks on the orbiter...are you speaking of the OMS (orbital maneuvering system) tanks? (these basically land with the propellant on board after the OMS deorbit burn, the last OMS burn of the mission) or the RCS (reaction control system) tanks (which are in fact dumped partially through the nozzles prior to reentry to control the vehicle's weight and balance for landing)?
The serpentine path is strictly caused by aerodynamics, with the shuttle banking left and right to manage lift from the wings, vs drag of the vehicle. There is some RCS thruster firing early on in the upper fringes of the atmosphere, but the aerodynamic control surfaces take over pretty quickly as the atmosphere starts "working" on the vehicle's surfaces.