METD WEATHER CALLS FOR A 66-70% ACCEPTABLE CONDITIONS FOR LAUNCH OF SPACE SHUTTLE DISCOVERY

METD WEATHER

Akshay Deoras

Severe Weather Forecaster

CONCERNING - WEATHER CONDITIONS FOR LAUNCH OF SPACE SHUTTLE DISCOVERY ON STS 133 MISSION FROM KENNEDY SPACE CENTER,FL LAUNCH PAD 39A

LAUNCH COMMIT CRITERIA FOR SPACE SHUTTLE AS PREPARED BY NASA

1] TEMPERATURE

1] TANKING WILL NOT BEGIN IF 24HR TEMPERATURE has been BELOW 41F (5C) AT MINIMUM OR ABOVE 99F

THE 24HR MIN TEMP ON 2-3NOV WILL BE AROUND 18-19C WHICH MEANS TANKING WILL BE PERMITTED AND MAX WILL BE AROUND 26C. (84F)

SO FROM WEATHER POINT OF VIEW, TANKING IS "GO"

2] the temperature is lower than the prescribed minimum value for longer than 30 minutes unless sun angle, wind, temperature and relative humidity conditions permit recovery. The minimum temperature limit in degrees F. is specified by the table below and is a function of the five minute average of temperature, wind and humidity. The table becomes applicable when the observed temperature reaches 48 degrees. In no case may the Space Shuttle be launched if the temperature is 35 degrees or colder.

Wind Speed	Relative Humidity
(kts)	0-64%	65-74%	75-79%	80-89%	90-100%
0 - 1	48	47	46	45	44
2	47	46	45	44	43
3	41	41	41	40	39
4	39	39	39	39	38
5 - 7	38	38	38	38	38
8 - 14	37	37	37	37	37
>14	36	36	36	36	36

The above table can be used to determine when conditions are again acceptable for launch if parameters have been out of limits for thirty minutes or less. If longer than thirty minutes, a mathematical recovery formula of the environmental conditions is used to determine if a return to acceptable parameters has been achieved. Launch conditions have been reached if the formula reaches a positive value.

THE ABOVE RULE [2] DOESN'T APPLY AS MIN AND MAX TEMP AT LAUNCH TIME ARE WITHIN THE ACCEPTABLE WINDOW

3] WINDS

RULE- TANKING WILL NOT BEGIN IF THE WIND FORECAST OR ACTUAL IS OVER 42KT FOR NEXT 3HRS

FORECAST- WIND SPEED IS GOING TO REMAIN NEAR 7-9KT DURING THE LAUNCH WINDOW.

FORECAST SAYS "GO" FOR TANKING

RULE- WIND AT LAUNCH VARIES FROM MISSION TO MISSION

4] LIGHTNING

RULE- LIGHTNING AND ELECTRIC FIELD WITH TRIGGERING POTENTIALS ARE NOT ALLOWED

IF FORECAST IS FOR 20% CHANCE OF LIGHTNING THEN TANKING WILL NOT BEGIN

WITHIN 5NM OF LAUNCH PAD, THE ONE MINUTE AVERAGE OF ELECTRIC INTENSITY MUST REMAIN BETWEEN +1KV/M TO -1KV/M

VALUES EXCEEDING THIS LIMIT ARE NOT ALLOWED

FORECAST

The forecast doesn't call for a thunderstorm with lightning potentials and strong electric intensity

So tanking is go from this point of view

5] PRECIPITATION

NOT ALLOWED AT LAUNCH PAD OR AROUND THE LAUNCH PAD

FORECAST- FORECAST CALLS FOR A 30% CHANCE OF RAINS AT LAUNCH WINDOW PERIOD AT KENNEDY SPACE CENTER,FL AND ACCUMULATION AROUND 1"

FORECAST WILL VERY ON THE LAUNCH DAY .

METD WEATHER FORECASTS- ITS A "GO OR NO GO" DECISION AND WILL BE BEST DECIDED ON THE LAUNCH DAY SEEING THE RADAR

6] CLOUD CEILING

RULE- DIRECT OBSERVATION OF SPACE SHUTTLE IS REQUIRED FOR FIRST 8000FT

SO CLOUD CEILING SHOULD BE ABOVE 8000FT

Forecast- Forecast calls for some low clouds of ceiling around 3000ft

The thickness of the clouds is expected to be low and might favor for a launch as in this case, clouds must be light

IN ALL,

METD WEATHER FORECASTS CALLS FOR A 66-70% ACCEPTABLE CONDITIONS AT THE LAUNCH TIME AS AROUND 4 RULES OUT OF 6 PROMINENTLY ARE ACCEPTABLE. NASA CALLS FOR A 70% FAVORABLE CHANCE WHICH IS NEAR TO METD WEATHER'S VALUE

** 30% UNACCEPTABLE CONDITIONS DUE TO LIGHT PRECIPITATION AND CLOUD CEILING PROBLEM.

** GO OR NO GO FOR LAUNCH WILL BE BETTER DECIDED FEW HOURS TO THE LAUNCH SEEING THE RADAR