Sending the Wrong Message to Students

Editor's note: Imagine a science teacher in Washington, DC giving out a homework assignment in the next day or so. She tells her class to use the web and find a NASA resource that will predict when the ISS will pass overhead on 31 January 2006.

The kids go home, hop on the computer and start Googling for NASA websites. Some of them end up at a NASA HQ website. Others end up at NASA's human spaceflight website at JSC. They look up Washington DC, record the times, and hand them in the next day. Imagine the teacher's consternation when she discovers that NASA has more than one official website for such things, and that the websites give different answers.

What is she going to tell her class? Both answers can't be right. And what does she tell her class the next time she is inclined to encourage them to pursue a career in space? Accuracy is supposed to be important.

Details below

NASA has several pages where you can look up your city and see when the ISS will travel overhead (and be visible). One page is at NASA HQ, the other page is at NASA JSC. Have a look at the inconsistent data for viewing a pass of the ISS over washington DC on 31 January 2006:

According to the NASA JSC human spaceflight tracking page:

Tue Jan 31/05:36 AM
Duration: 1 minute
Max elevation: 41 degrees
Approach: 41 above NE
Departure: 16 above NE

According to the NASA HQ spaceflight tracking page:

Date: 31-Jan-2006
Pickup time: 5:33 AM
Direction (from/to) NE/ENE
Duration: 2 minutes
Maximum elevation above horizon: 36

So, depending on which official NASA ISS tracking page you believe the ISS will fly over Washington, D.C. starting at either 5:36 am or 5:33 am EST, it will be visible for either 1 minute or 2 minutes; it will reach a maximum elevation of either 41 degrees or 36 degrees, it will appear in the northeast and head either for the northeast or east northeast.

Here are detailed sightings for ISS passes over Washington, DC for the next week or so. As you can see there are multiple inconsistencies.


If I go to this page at NASA HQ I get these viewing times for Washington, DC:

Naked-Eye Visibility Data
for Washington, D.C., U.S.A.
1/5/2006 - 2/1/2006

DATE PICKUP TIME
hrs:min
(Local Time)
DIRECTION
(from/to)
DURATION
(minutes)
MAXIMUM
ELEVATION
ABOVE
HORIZON
(degrees)
11-Jan-2006  6:01 PM  NNW/N  10 
13-Jan-2006  6:50 PM  NW/NNW  24 
14-Jan-2006  5:40 PM  NNW/ENE  18 
15-Jan-2006  6:04 PM  NW/ESE  43 
16-Jan-2006  6:29 PM  WNW/SSE  41 
17-Jan-2006  6:54 PM  W/SSW  11 
18-Jan-2006  5:43 PM  WNW/SSE  38 
19-Jan-2006  6:08 PM  W/SSW  11 
26-Jan-2006  6:38 AM  SSW/ENE  24 
28-Jan-2006  5:52 AM  SSW/ENE  26 
29-Jan-2006  6:17 AM  SW/NE  75 
30-Jan-2006  5:09 AM  E/ENE  21 
30-Jan-2006  6:41 AM  W/NNE  26 
31-Jan-2006  5:33 AM  NE/ENE  36 
1-Feb-2006  5:57 AM  N/NNE  22 


If I go to this page at NASA's human spaceflight website I get these results for Washington DC:

***** WASHINGTON, D.C. *****



THE FOLLOWING ISS SIGHTINGS ARE POSSIBLE FROM THR JAN 26 TO TUE FEB 07

SATELLITE
LOCAL
DURATION
MAX ELEV
APPROACH
DEPARTURE
DATE/TIME
(MIN)
(DEG)
(DEG-DIR)
(DEG-DIR)
ISS
Sat Jan 28/05:54 AM
2
25
10 above SSW 25 above SSE
ISS
Sun Jan 29/06:18 AM
5
74
10 above SW 13 above NE
ISS
Mon Jan 30/06:44 AM
5
24
11 above W 10 above NNE
ISS
Tue Jan 31/05:36 AM
1
41
41 above NE 16 above NE
ISS
Wed Feb 01/05:59 AM
2
23
23 above NNW 10 above NNE
ISS
Thr Feb 02/06:23 AM
2
12
11 above NW 10 above N


Check these three ISS tracking pages. The first is from JSC, the bottom two are from MSFC (click on image for current version). Note that although the times represented are within seconds of each other the ISS is shown to be at three different altitudes ranging from 351.22 km for JSC to either 362.6 or 361.9 km for MSFC. Clearly they can't all be correct - even adjusting for slight differences in time shown. If NASA's intent is simply to show a close approximation, then why not just pick one of these three simulations instead of having three functioning simultaneously?




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About this Entry

This page contains a single entry by Keith Cowing published on January 26, 2006 5:54 PM.

Different Messages For Different Audiences was the previous entry in this blog.

Challenger: Making Sure Historians Get It Right is the next entry in this blog.

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