Measurement of electric current, magnetic field, and electron density in ionosphere using Nike-Apache sounding rocket

Cahill, L. J., Jr.

Maynard, N. C.

English

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Department of Physics 
UNIVERSITY OF NEW HAMPSHIRE 
Durham 
https://ntrs.nasa.gov/search.jsp?R=19650022482 2020-03-17T00:58:29+00:00Z
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PRELIMINARY RESULTS OF MEASUREMENTS 
OF SQ CURRENTS AND THE EQUATORIAL 
ELECTROJET NEAR PEN 
bY 
N. C. Maynard 
and 
L. J. Cahill Jr. 
Physics Department 
University of New Hampshire 
Durham, New Hampshire 
This work was supported by National Aeronautics 
and Space Administration Contract NAS 5-3043. 
cc. Preliminary Results of Measurements of SQ Currents 
and the Equatorial Electrojet  near Peru 
Four Nike-Apache sounding rockets were launched from 
the  USNS Croatan during March, 1965, t o  measure e l e c t r i c a l  
currents i n  the ionosphere. 
of Peru were par t  of the  recent NASA Mobile Launch Expedi- 
These f l i g h t s  off  the  coast 
t ion.  Preliminary magnetometer r e s u l t s  from two of these 
f l i g h t s  a r e  of i n t e r e s t  i n  establishing the charac te r i s t ics  
of the equator ia l  e lec t ro jec t  (Singer e t  a l ,  1951; Cahill ,  
1959; .Maward e t  al, 1965; Maynard and Cahill, 1965), and 
of the low a l t i t ude  SQ current system (Burrows and Hall, 
1965; Davis e t  al, 1965). 
The rockets were instrumented t o  measure the magnetic 
f i e l d  and the  electron density. A nuclear f ree  precession 
magnetometer measured the scalar  magnitude B of the  
ear th’s  magnetic f ie ld ,  and a DC Langmuir probe was used 
t o  measure the r e l a t ive  electron density. 
have been described ea r l i e r  (Maynard and Cahill, 1965 ) . 
included i n  the  payload for t ra jec tory  and aspect determina- 
These instruments 
Also 
t ions  were a barometric pressure switch, an ionization cham- 
ber densitcmeter t o  rnonitor air pressure, and a magnetic 
aspect sensor. An FM-FMtelemetry system transmitted the  
s ignal  t o  the  ground, where it was recorded with a 100 kc 
reference s ignal  for l a t e r  data processing. 
Flight UNH 65-5 (NASA 14.82 UE) was launched f’rom the 
- 2 -  
J 
Croatan at 1100 hours local time on March 12, 1965, fiom 
11 
0 
25' south latitude and 81' 20' west longitude near 
the geomagnetic dip equator and near the center of the 
electrojet. The trajectory was computed to fit the baro- 
switch operation times at 70,000 feet. Peak altitude was 
calculated to 173 km. 
first minute of flight, an estimate of range was made, and 
the theoretical field was computed over an approximate 
From radar plot board data for the 
trajectory, using the coefficients of Leaton and Evans 
(private communication). 
Figure 1 depicts the difference between the measured 
field and the computed field, plotted as a f'unction of 
altitude. The slope starts to change about 95 km, and 
the maximum current appears to be located at 108 km. The 
current layer extends upward with decreasing intensity to 
about 130 km in similar manner to that observed by Maynard 
and Cahill (1965) over India. 
is about 120 @;amas, in comparison with 60 to 70 gammas 
The total change in field 
for the mid-day India flights. On the downward leg the 
current is centered near 108 km. 
above 130 km on the downward leg is believed to be the 
The long sloping tail 
result of inaccuracy of the preliminary tra3ectory used 
in calculating the theoretical field, 
above 140 km on the upward leg is also attributed to this 
The gradual rise 
factor. The wide fluctuations below 85 km on the down- 
- 3 -  
ward leg were apparently caused by overturning of the 
rocket spin axis, as they are correlated with similar 
fluctuations in the signal from the magnetic aspect sensor. 
Flight U" 65-2 (NASA 14.85 UE) was launched at 1136 
hours local time on March 9, 1965, ftom 3' 07' south 
latitude and 84' 22' west longitude. 
8' north of the magnetic dip equator, hence well to the 
north of the equatorial electrojet, which is estimated to 
be 6 O  wide over Peru (extending 3' north and south of the 
dip equator, Forbush and Casaverde, 1961). For initial 
analysis, time of peak altitude was taken as the time of 
This was more than 
minimum magnetic field. The radar tracking data in the 
early portion of the flight were also used in computing 
a trajectory, Peak altitude was determined to be 161.8 
km. 
trajectory, using the same range as established for 65-5 
and using Leaton and Evans coefficients. 
The theoretical field was computed over an approximate 
The difference between the measured field and the 
theoretical field is shown in Figure 2. 
small variations observed are apparently due to precession 
of the rocket with a field of about 3 gammas. 
over the curves denote the time of maximum positive effect 
of the precession, while the arrows under the curves denote 
the maximum negative effect. 
the precession record obtained f'rom the magnetic aspect 
Many of the 
Tne arrows 
These times were taken from 
I 
- 4 -  
data. The SQ current measured i s  more diffnse than the  
e lec t ro je t ,  extending from 93 km up t o  about 130 km 
(upward l e g  da ta ) .  
e f f ec t  on the downward leg is  thought t o  be due t o  pre- 
liminary t ra jec tory  errors. 
lo5 and 110 km on the upward l eg  (100 and 105 km on the  
downward leg) ,  apparently is  not due t o  precession and 
suggests a double-layered current s t ructure  with the  peak 
of  the lower layer a t  100 km and of the upper layer  a t  
118 km (upward leg  data) .  
the current layers  was about 45 gammas. 
which widely deviate f romthe curve on the upward leg a re  
believed t o  be the r e s u l t  of noisy magnetometer signals.  
The fluctuations below 65 km on the downward leg a re  
again due t o  overturning of the rocket spin axis.  
The s h i f t  downward i n  a l t i t u d e  of  t h i s  
The change of slope between 
Total  magnetic change due t o  
The two points 
Magnetograms for  the two f l i g h t  days from the  
0 
Peruvian s ta t ions  a t  H&nuco, (9.9 South; 72.9' West), 
and Ca?iete (13.1' South; 76.4 West), a r e  shown i n  
Figure 3 (records provided by Scott  Forbush of the  Carnegie 
I n s t i t u t e  of Washington, Department of Te r re s t r i a l  Mag- 
netism). Launch times of the two f l i g h t s  are indicated 
on the  appropriate magnetograms. These s ta t ions  a re  
respectively above and below the  e lec t ro jec t  center, as is 
apparent by the g component variation. 
closer t o  the  e lec t ro jec t  center, i s  not ye t  available t o  
us, s o  detai led comparison of the rocket and ground r e s u l t s  
0 
The Huhncayo record, 
- 5 -  
.a' 
will not be attempted here, It i s  
the  rockets were launched near the 
apparent, however, t h a t  
peak of the diurnal 
var ia t ion on each day, and t h a t  the ear th 's  magnetic 
f i e l d  was reasonably quiet ,  
Further analysis of these two f l i g h t s  and of  the  
other two (March 10, 1965, a t  1100 hours, 6' 30' South; 
84' 32' West; March 12, 1965, at 0830 hours, 1' 23' 
South, 81 25' West) is now i n  progress and w i l l  be re- 
ported i n  d e t a i l  i n  a l a t e r  paper. 
0 
This work was supported by NASA Contract NAS 5-3043. 
We acknowledge the assistance of Paul Lavoie of the UNH 
Physics Department and o f t h e  personnel of the NASA 
Mobile Launch Expedition. 
. 
A References 
Burrows, K. and S. H. Hall, Rocket measurements of the 
geomagnetic field above Woomera, South Australia, 
J. Geophys. Res., 70, 2149-2152, 1965. 
Cahill, L. J., Jr., Investigation of the equatorial elec- 
trojet by rocket magnetometer, J. Geophys. Res., 64, - 
489-503, 1959. 
Davis, T. N., J. D. Stolarik and J. P. Heppner, Rocket 
measurements of SQ currents at mid-latitudes, Tech. 
Rpt. X-612-65-226, Goddard Space Flight Center, 1965. 
Forbush, S. E. and M. Casaverde, Equatorial electrojet in 
Peru, Carnegie Institution of Washington Publication 
d 620 1961. 
lkynard, M. C. and L. 3 .  Cahill, Jr., Measurement of the 
equatorial electrojet in India, sub, J. Geophys. Res., 
June, 1965. 
Maynard, N. C., L. J. Cahill, Jr. and T. S. G. Sastry, 
Preliminary results of measurements of the equatorial 
electrojet over India, J. Geophys. Res., 70, 1241- -
1245, 1965. 
Sirier, S, F.,  E. Maple, and W. A. Bowen, Jr., Evidence 
ionosphere current from rocket experiments near the 
geomagnetic equator, J. Geophys . Res., - 56, 265-281, 
1951. 
. 
4. 
Captions 
. 
Figure 1. The difference between the  measured f i e l d  and 
the calculated f ie ld ,  plot ted against  a l t i t u d e  
for UNH 65-5. 
Figure 2. The difference between the measured f i e l d  and 
the  calculated f i e l d  as a f'unction o f  a l t i t ude  
f o r  UNH 65-2. 
denote maximums i n  the  e f f ec t  from rocket 
precession, while those below the curves 
indicate  minimums. 
ITU uc begrams 
a t  Hu\anuco and CaEete i n  Peru, for the days of 
the  two launchings. 
f l i g h t  i s  denoted on the  respective magnetogram. 
The arrows above the  curves 
yLgme 3. f m m  the imgnet ic  obscrvatcries 
Time of launch for each 
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Preliminary results of measurements of sq currents and the equatorial electrojet near peru

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