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 | 2 | 10 |
13-Jan-2006 | 6:50 PM | NW/NNW | 2 | 24 |
14-Jan-2006 | 5:40 PM | NNW/ENE | 4 | 18 |
15-Jan-2006 | 6:04 PM | NW/ESE | 5 | 43 |
16-Jan-2006 | 6:29 PM | WNW/SSE | 5 | 41 |
17-Jan-2006 | 6:54 PM | W/SSW | 4 | 11 |
18-Jan-2006 | 5:43 PM | WNW/SSE | 6 | 38 |
19-Jan-2006 | 6:08 PM | W/SSW | 4 | 11 |
26-Jan-2006 | 6:38 AM | SSW/ENE | 6 | 24 |
28-Jan-2006 | 5:52 AM | SSW/ENE | 6 | 26 |
29-Jan-2006 | 6:17 AM | SW/NE | 5 | 75 |
30-Jan-2006 | 5:09 AM | E/ENE | 2 | 21 |
30-Jan-2006 | 6:41 AM | W/NNE | 5 | 26 |
31-Jan-2006 | 5:33 AM | NE/ENE | 2 | 36 |
1-Feb-2006 | 5:57 AM | N/NNE | 2 | 22 |
If I go to this page at NASA’s human spaceflight website I get these results for Washington DC:
Sat Jan 28/05:54 AM | 10 above SSW | 25 above SSE | |||
Sun Jan 29/06:18 AM | 10 above SW | 13 above NE | |||
Mon Jan 30/06:44 AM | 11 above W | 10 above NNE | |||
Tue Jan 31/05:36 AM | 41 above NE | 16 above NE | |||
Wed Feb 01/05:59 AM | 23 above NNW | 10 above NNE | |||
Thr Feb 02/06:23 AM | 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?