NORAD Data Format

Data from satellite operators and trackers is presented in the format of NORAD style TLEs (Two Line Elements) that provide all the required information to determine the objects position. NORAD stands for North American Aerospace Defence Command and tracks all space objects, in the near Earth environment, larger than 0.1m. These TLEs have been produced using Satellite Tool Kit (STK) running the SPG4 industry standard orbital propagation model, and can be found under a cubesat section (currently with 18 spacecraft listed) at http://celestrack.com/NORAD/elements. 19 cubesats have made orbit at this time. The TLEs are only maintained at the operators request, hence why a cubesat may be missing from the list. Legislation has recently been passed by the US government allowing non-us-government-entities (NUGES) access to this NORAD data.

Line 1

Column Characters Description
1 1 Line no. id
3 5 Catalogue no.
8 1 Security Classification
10 8 International id
19 14 Year, Day of Year and Fraction of Day
34 1 Sign of 1st time derivative of mean motion
35 9 1st time derivative of mean motion (rev per day2)
45 1 Sign of 2nd time derivative of mean motion
46 5 2nd time derivative of mean motion (rev per day3)
51 1 Sign of 2nd time derivative exponent of mean motion
52 1 2nd time derivative exponent of mean motion
54 1 Sign of B* drag term
55 5 B* drag term = (CD A)/m
60 1 Sign of B* exponent
61 1 B* exponent
63 1 Ephemeris Type (orbital model used)
65 4 Element no. (Starts at one and increases every time the elements are updated)
69 1 Check sum, Mod 10

Line 2

Column Characters Description
1 1 Line no. id
3 5 Catalogue no.
9 8 Inclination
18 8 Ra of ascending node
27 7 Eccentricity with assumed leading decimal
35 8 Argument of perigee
44 8 Mean Anomaly
53 11 Revolutions per day (mean motion)
64 5 Revolutions at Epoch
69 1 Check sum, Mod 10

The 3rd year 2008 pair project on the ADCS environment, accuracy and data rate can be found here.

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