Urania

A blog named for the muse of Astronomy containing musings by an astronomer

STS-131 Re-Entry over Minnesota !?!

Posted on April 19, 2010 by admin

[Addendum: NASA TV reports showers within 30 miles of Kennedy Space Center means landing on Orbit 237 has been cancelled. 🙁 – Updated at 5:57 am CDT, April 20. The landing on Orbit 238 looks more likely. Unfortunately for us, that takes the Shuttle far to the west of us during its landing.]

What’s going on with this page? The Space Shuttle Discovery was not able to land on the morning of Monday, April 19 due to bad weather atthe Kennedy Space Center. This however means we in Minnesota now have a good chance to see and maybe even hear the Space Shuttle Discovery re-enter the atmosphere in the early morning of Tuesday, April 20 in the half-hour before sunrise!

How will we know if the re-entry of the Space Shuttle will be over Minnesota? You can check the STS-131 Landing Blog. By 5:31 am CDT the Space ShuttleDiscovery will have to start its deorbit burn, so we should know by then if the landing will be over Minnesota. [Addendum: NASA TV reports showers within 30 miles of Kennedy Space Center means landing on Orbit 237 has been cancelled. 🙁 – Updated at 5:57 am CDT, April 20. The landing on Orbit 238 looks more likely.]

What is the Path the Space Shuttle will follow During Re-Entry? The first landing opportunity for the Space Shuttle Discovery comes during Orbit 237 and would follow the path shown below (From NASA’s STS-131 Ground Tracks page)

What do you mean “hear” the space shuttle? If the Space Shuttle passes over Minnesota, it will have slowed down a bit already, but it will still be traveling about 13,600 miles per hour or a bit over Mach 18!  As such, even if we don’t see the Space Shuttle, we may in fact hear the twin sonic booms about half a second apart of the re-entry a few minutes after it flies overhead since the shuttle will be only about 45 miles overhead!  There are two sonic booms, one generated by compression of air near the nose of the Shuttle, and another by compression near the tail.  Its not just me, AccuWeather is claiming we might well hear the sonic boom! Furthermore, Space.com has this article on the (now aborted) entry that was going to be over the Dakotas on Monday morning, and it says the first effects of Earth’s atmosphere on the Space Shuttle are at an altitude of about 75 miles. Since it would be only about 44 miles over Minnesota, I suspect we might well hear it. I figure if the Space Shuttle is at 44 miles and sound takes about 5 seconds per mile, we should hear any sonic boom about 2 to 3 minutes to get to the ground (WARNING: I am not taking into account variations in the speed of sound due to varying air density/temperature. I could be off by up to a minute).

What do the twin sonic booms sound like? Here is a YouTube recording of the Shuttle’s twin sonic boom. From what I have read, the twin sonic booms can be heard about 40 miles to either side of the flight path in the right situations.

When will the Space Shuttle Pass over Minnesota if it does Re-Enter over Minnesota? If the Space Shuttle Discovery re-enters the Earth’s atmosphere during Orbit 237, the NASA Human Space Flight Realtime data page tells us the following:

 

Details for the Fargo-Moorhead Area:

The Space Shuttle will come over the horizon in the northwest at 6:12:58 am CDT in the northwest. However, it will not clear the Earth’s shadow until about 30 seconds later at 06:13:29 am CDT. It will appear to speed up as it rises in the sky over the next 2 minutes until it is almost overhead. The closest approach will be at 6:15:16 am CDT when the Shuttle is only 43 miles away when it 71 degrees above the horizon (almost overhead) a little bit to the northwest moving toward the southeast! The Shuttle will remain over the horizon until 6:17:50 am CDT. Fortunately for Fargo-Moorhead, sunrise is at 6:30 am CDT, so we have the best shot in Minnesota for seeing the Shuttle in dark skies. It may still be difficult to spot given the dawn sky. if you don’t see it, be sure to stick around long enough listen for the sonic boom a few minutes later (about 6:17 to 6:19 am it should reach the ground)! Details on the passage are listed below (azimuth is angle east of north, elevation is angle above the horizon).

Local Time Azimuth Elevation Range Height of Sun above Horizon (as seen by Shuttle) Angle between Sun and Shuttle
Deg E of N Deg Miles Deg Deg
Tue-Apr-20@06:12:58 297.2 0.3 566 -1.2 158.6
Tue-Apr-20@06:12:58 297.5 1.3 503 -0.5 158
Tue-Apr-20@06:13:29 297.8 2.5 440 0.1 157.5
Tue-Apr-20@06:13:44 298.1 3.8 378 0.7 156.9
Tue-Apr-20@06:13:59 298.4 5.5 317 1.3 156.3
Tue-Apr-20@06:14:15 298.7 7.7 256 1.9 155.8
Tue-Apr-20@06:14:30 299 11 197 2.5 155.2
Tue-Apr-20@06:14:45 299.3 16.6 138 3.1 154.6
Tue-Apr-20@06:15:01 299.6 29.2 84 3.7 154
Tue-Apr-20@06:15:16 299.7 71 43 4.3 153.4
Tue-Apr-20@06:15:31 120.5 42.9 60 4.8 152.8
Tue-Apr-20@06:15:47 120.7 21.3 109 5.3 152.2
Tue-Apr-20@06:16:02 121.1 13.3 163 5.9 151.5
Tue-Apr-20@06:16:17 121.4 9.1 217 6.4 150.9
Tue-Apr-20@06:16:33 121.8 6.5 271 6.9 150.3
Tue-Apr-20@06:16:48 122.2 4.7 325 7.3 149.7
Tue-Apr-20@06:17:04 122.6 3.2 378 7.8 149.1
Tue-Apr-20@06:17:19 123 2.1 430 8.2 148.5
Tue-Apr-20@06:17:34 123.4 1.1 481 8.7 147.9
Tue-Apr-20@06:17:50 123.8 0.3 532 9 147.3

 

Details for the Twin Cities Area:

The Space Shuttle will come over the horizon in the northwest at 6:14 am CDT in the northwest and it will appear to speed up as it rises over the next 2 minutes until it is almost overhead. The closest approach will be at 6:16:17 AM when the Shuttle is only 44 miles away when it 65 degrees above the northeastern horizon (about 2/3 of the way to the zenith from the horizon) moving toward the southeast! The Shuttle will remain over the horizon until almost 6:19 am CDT. Unfortunately sunrise is at 6:19 am CDT, so you will be fighting the intense dawn sky light to see the Shuttle. However, listen for the sonic boom a few minutes later! Details on the passage are listed below (azimuth is angle east of north, elevation is angle above the horizon).

Local Time Azimuth Elevation Range Height of Sun above Horizon (as seen by Shuttle) Angle between Sun and Shuttle
Deg E of N Deg Miles Deg Deg
Tue-Apr-20@06:13:59 304.1 0.8 528 1.3 155
Tue-Apr-20@06:13:59 304.7 1.9 467 1.9 154.5
Tue-Apr-20@06:14:30 305.4 3 407 2.5 153.9
Tue-Apr-20@06:14:45 306.2 4.4 348 3.1 153.4
Tue-Apr-20@06:15:01 307.2 6.2 289 3.7 152.8
Tue-Apr-20@06:15:16 308.5 8.7 231 4.3 152.2
Tue-Apr-20@06:15:31 310.5 12.4 175 4.8 151.7
Tue-Apr-20@06:15:47 314 19 120 5.3 151.1
Tue-Apr-20@06:16:02 323.5 34.4 71 5.9 150.5
Tue-Apr-20@06:16:17 36.9 65.1 44 6.4 150
Tue-Apr-20@06:16:33 107.2 33.9 70 6.9 149.4
Tue-Apr-20@06:16:48 116.5 18.8 118 7.3 148.8
Tue-Apr-20@06:17:04 120.1 12.3 168 7.8 148.3
Tue-Apr-20@06:17:19 122.1 8.7 219 8.2 147.7
Tue-Apr-20@06:17:34 123.5 6.3 270 8.7 147.1
Tue-Apr-20@06:17:50 124.6 4.6 319 9 146.6
Tue-Apr-20@06:18:05 125.5 3.2 368 9.4 146
Tue-Apr-20@06:18:20 126.4 2.1 416 9.8 145.5
Tue-Apr-20@06:18:36 127.1 1.2 463 10.1 145
Tue-Apr-20@06:18:51 127.9 0.4 509 10.4 144.5

 

Details for the Rochester Area:

The Space Shuttle will come over the horizon in the northwest at 6:14 am CDT in the northwest and it will appear to speed up as it rises over the next 2 minutes until it is almost overhead. The closest approach will be at 6:16:33 AM when the Shuttle is only 65 miles away when it 37 degrees above the northern horizon (about 1/3 of the way to the zenith from the horizon) moving toward the southeast! The Shuttle will remain over the horizon until almost 6:19 am CDT. Unfortunately sunrise is at 6:18 am CDT, so you may lose the Space Shuttle in the dawn glare. However, listen for the sonic boom a few minutes later! Details on the passage are listed below (azimuth is angle east of north, elevation is angle above the horizon).

Local Time Azimuth Elevation Range Height of Sun above Horizon (as seen by Shuttle) Angle between Sun and Shuttle
Deg E of N Deg Miles Deg Deg
Tue-Apr-20@06:14:15 308.7 0.6 538 1.9 154.2
Tue-Apr-20@06:14:15 309.7 1.6 479 2.5 153.7
Tue-Apr-20@06:14:45 310.9 2.7 420 3.1 153.1
Tue-Apr-20@06:15:01 312.4 4 361 3.7 152.6
Tue-Apr-20@06:15:16 314.3 5.6 304 4.3 152
Tue-Apr-20@06:15:31 316.9 7.8 248 4.8 151.5
Tue-Apr-20@06:15:47 320.7 10.8 193 5.3 150.9
Tue-Apr-20@06:16:02 327.3 15.7 141 5.9 150.4
Tue-Apr-20@06:16:17 341.2 24.4 95 6.4 149.8
Tue-Apr-20@06:16:33 18.6 37.2 65 6.9 149.3
Tue-Apr-20@06:16:48 74.6 32.1 73 7.3 148.7
Tue-Apr-20@06:17:04 99.2 20.1 110 7.8 148.2
Tue-Apr-20@06:17:19 109.1 13.4 156 8.2 147.7
Tue-Apr-20@06:17:34 114.4 9.5 203 8.6 147.1
Tue-Apr-20@06:17:50 117.7 6.9 252 9 146.6
Tue-Apr-20@06:18:05 120.1 5.1 299 9.4 146.1
Tue-Apr-20@06:18:20 121.9 3.7 346 9.8 145.6
Tue-Apr-20@06:18:36 123.4 2.6 392 10.1 145.1
Tue-Apr-20@06:18:51 124.7 1.6 437 10.4 144.6
Tue-Apr-20@06:19:06 125.9 0.8 481 10.7 144.1
Tue-Apr-20@06:19:22 127 0.1 524 11 143.6

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