Space Shuttle weather for final Hubble fix mission

May 11, 9:11 AMBaltimore Weather ExaminerJustin Berk

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Sunset on May 10, 2009.  AP Photo/Chris O'Meara

Today begins the final mission to repair the aging Hubble Space Telescope by the Space Shuttle Atlantis.  At 19 years old, the Hubble is well past it's life span of 15 years.  It has been a tremendous asset to the field of astronomy showing images of space, farther and deeper than ever seen before. This mission will included replacing about 110 screws the size of a pea with gloves the size of hockey mitts.  It will also replace a few batteries and cameras.  Since the telescope was not designed for repair, it will be a tenuous job, but not the first time work has been done. Click here for the slide show below

Hubble is monitored locally by the Goddard Space Flight Center in Greenbelt, MD.  The success of this mission is important since the next Space Telescope, The James Webb, is set for orbit in 2014.

The weather along Florida's 'Space Coast', has been described as near perfect, but clouds will try to roll in from the west.  The general storm affecting the Gulf Coast to Mid Atlantic states will stay to the north, allowing for good conditions at liftoff this afternoon at 2pm. Just in case, a second shuttle, Endeavour, is on another launch pad waiting for any assistance

Weather is very important for the Space Shuttle, with a small window of opportunity to avoid problems.  Problems can range fro temperatures too cold, to a storm without a storm.  The weather criteria below is from an official press release from the Kennedy Space Center,  January 2000.

Cold temperatures:

It doesn't have to be near freezing, for ice buildup during the launch.  The Challenger explosion in 1987 was due to icing, but the ground temperatures were in the mid 30s.The launch of Challenger had been delayed five times due to bad weather, January 28 was the coldest day that NASA have ever launched a shuttle. The time had come, at 11:38 AM Eastern Standard Time, Challenger left Pad 39B at Kennedy.  The temperature at ground level at Pad 39B was 36°F, that was 15°F cooler than any other previous launch by NASA.  The O-ring seal was believed to be compromised by the cold air.

No tanking or fueling if the temperature is below 41°F

After fueling begins, the countdown stops if the temperature exceeds 99°F for 30 minutes.  There is a complicated equation of wind and humidity when temperatures drop below 48°F.  The shuttle will not lift off if the temperature is below 35°F

Precipitation: No launch if there is any rain/snow on the pad or within the flight path.

Wind: Tanking will not begin if the wind is observed or forecast to exceed 42 knots for the next three hour period.

For launch the wind constraints at the launch pad will vary slightly for each mission. The peak wind speed allowable is 30 knots. However, when the wind direction is between 100 degrees (south southwest) and 260 degrees (almost due west), the peak speed varies for each mission and may be as low as 24 knots.

Lightning (and electric fields with triggering potential):

• Tanking will not begin if there is forecast to be greater than a 20% chance of lightning within five nautical miles of the launch pad during the first hour of tanking. The launch director with the concurrence of the safety director may make an exception after consultation with the Shuttle Weather Officer.
• Do not launch if lightning has been detected within 10 nautical miles of the pad or the planned flight path within 30 minutes prior to launch. Launch may occur if the source of lightning has moved more than 10 nautical miles away from the pad or the flight path and a field mill, used to measure electric fields, is located within 5 nautical miles of the lightning flash.
• The one-minute average of the electric field mill network may not exceed -1 or +1 kilovolt per meter within five nautical miles of the launch pad or the lightning flash at any time within 15 minutes prior to launch. This field mill criteria becomes -1.5 or + 1.5 kilovolts per meter if there are no clouds within 10 nautical miles of the flight path except those which are transparent. Also excepted are clouds with tops below the 41 degrees F. temperature level that have not have been previously associated with a thunderstorm, or associated with convective clouds having tops above the 14 degrees F. temperature level during the last three hours.
• Do not launch when lightning is observed and the cloud which produced the lightning is within 10 nautical miles of the flight path. Launch may not occur until 30 minutes has elapsed since the lightning flash, or the cloud has moved more than 10 nautical miles away.

Clouds: (types known to contain hazardous electric fields)

• Do not launch if any part of the planned flight path is through a layer of clouds any part of which is within 5 nautical miles is 4,500 feet thick or greater and the temperature of any part of the layer is between 32 degrees F. and -4 degrees F. Launch may occur if the cloud layer is a cirrus-like cloud that has never been associated with convective clouds, is located entirely at temperatures of 5 degrees F. or colder, and shows no evidence of containing water droplets.
• Do not launch through cumulus type clouds with tops higher than the 41 degree F. temperature level. Launch may occur through clouds as cold as 23 degrees F. if the cloud is not producing precipitation, and all field mills within 5 nautical miles of the flight path and at least one field mill within 2 nautical miles of the cloud center read between -100 volts per meter and +500 volts per meter.
• Do not launch 1.) through or within 5 nautical miles of the nearest edge of cumulus type clouds with tops higher than the 14 degree F level; 2) through or within 10 nautical miles of the nearest edge of cumulus clouds with tops higher than the -4 degrees F. level.
• Do not launch if the flight path is through any non-transparent clouds that extend to altitudes at or above the 32 degrees F. level which are associated with disturbed weather producing moderate or greater precipitation, or melting precipitation, within five nautical miles of the flight path.
• Do not launch through an attached anvil cloud. If lightning occurs in the anvil or the associated main cloud, do not launch within 10 nautical miles for the first 30 minutes after lightning is observed, or within 5 nautical miles from 30 minutes to 3 hours after lightning is observed.
• Do not launch if the flight path will carry the vehicle:

  a.) through non-transparent parts of a detached anvil for the first three hours after the anvil detaches from the parent cloud, or the first four hours after the last lightning occurs in the detached anvil.

  b.) within 10 nautical miles of non-transparent parts of a detached anvil for the first thirty minutes after the time of the last lightning in the parent or anvil cloud before detachment, or the detached anvil after its detachment.

  c.) within 5 nautical miles of non-transparent parts of a detached anvil for the first three hours after the time of the last lightning in the parent or anvil cloud before detachment, or the detached anvil after detachment, unless there is a field mill within 5 nautical miles of the detached anvil reading less than 1,000 volts per meter for the last 15 minutes and a maximum radar returns from any part of the detached anvil within 5 nautical miles of the flight path have been less than 10 dBZ (light rain) for 15 minutes.

• Do not launch if the flight path will carry the vehicle through a thunderstorm or cumulonimbus debris cloud which is not transparent and less than three hours old. Launch may not occur within five nautical miles of these debris clouds unless: 1) for 15 minutes preceding launch there is at least one working field mill within five nautical miles of the debris cloud; 2) all electric field mill readings are between -1 kilovolt and + 1 kilovolt per meter within five nautical miles of the flight path; 3) no precipitation has been detected in the debris cloud (less than 10 dbz by radar) within 5 nautical miles of the flight path.
• Do not launch if the flight path will carry the vehicle through any cumulus cloud that has developed from a smoke plume while the cloud is attached to the plume, or for the first 60 minutes after the cumulus cloud detaches from the smoke plume.

Formal Weather Briefings and weather equipment can be found here.