The article documents the operations encompassing the International Cometary Explorer (ICE) second Halley radial experiment centered around March 28, 1986. The support was provided by the Deep Space Network (DSN) 64-meter subnetwork. Near continuous support was provided the last two weeks of March and the first two weeks of April to insure the collection of adequate background data for the Halley radial experiment. During the last week of March, plasma wave measurements indicate that ICE was within the Halley heavy ion pick-up region

Efron, L.

Fanelli, N. A.

Muellerschoen, R. J.

English

NASA Technical Reports Server

TDA Progress Report 42-87 
ICE Second Halley Radial: 
July- September 1986 
TDA Mission Support 
and DSN Operations 
N. A. Fanelli 
TDA Mission Support and DSN Operations 
L. Efron and R. J. Muellerschoen 
Navigation Systems Section 
This article documents the operations encompassing the International Cometary 
Explorer (ICE) second Halley radial experiment centered around March 28, 1986. The 
support was provided by the Deep Space Network (DSN) 64-meter subnetwork. Near 
continuous support was provided the last two weeks of March and the first two weeks o f  
April to insure the collection of adequate background data for the Halley radial experi- 
ment. During the last week of March, plasma wave measurements indicate that ICE was 
within the Halley heavy ion pick-up region. 
I 1. Introduction While in Earth orbit, the geocentric range to ISEE-3 had 
heen on the order of 0.01 AU (1.5 X lo6 km) or less. While 
enroute to encounter with G-Z the geocentric range to ICE 
the 26-m antennas and required support from the DSN 64-m 
antennas for the remainder of the mission. 
The International Sun Earth Explorer (ISEE-3) was launched 
particles and fields; first monitoring the solar wind upstream 
of the Earth and later in the geomagnetic tail region. During 
this period, support of ISEE-3 was provided by the 26-m 
in 1978. Five years were spent in Earth Orbit, measuring grew to 0.51 AU. In January 1984, ICE went out of range of 
1 
antennas operated by the Ground Spacefight Tracking and 
Data Network (GSTDN). In December 1983, using a 119-km- 
altitude, lunar-gravity-assist swingby, the spacecraft was sent 
on a new mission to  intercept Comet Giacobini-Zinner (G-2). 
At perilune, the spacecraft was renamed the International 
Cometary Explorer (ICE). 
Mission Trajectory acrobatics and navigation from launch 
through comet encounter are covered in detail in Reference 1. 
The Comet G-Z Encounter operations are covered in Refer- 
~ ences2-7. 
The primary mission goal was to  make the first in situ 
measurement of a comet. This was achieved on September 11, 
1985 when the spacecraft passed unscathed through the G-Z 
tail 7800 km downstream of the nucleus. 
A secondary mission goal was to obtain measurernerlts iri 
the solar wind upstream of Halley’s Comet for possible correla- 
tion with Earth- and space-based observations of that celes- 
tial visitor during the same time frame. Twice during inter- 
planetary cruise the ICE orbit placed the spacecraft in near 
285 
https://ntrs.nasa.gov/search.jsp?R=19870005925 2020-03-20T12:10:12+00:00Z
radial alignment between the sun and Halley’s Comet. This 
occurred first in October-November 1985 and again late in 
March 1986. This is illustrated in Fig. 1. The second Halley 
radial alignment occurred when ICE approached within 
30 X lo6 km of the comet. Around this time, the plasma wave 
instrument aboard ICE made measurements indicative of ions 
produced by heavy neutrals emitted by Halley’s Comet. 
Hence, ICE can lay claim to being the sixth member of the 
Halley Armada, behind Sakigake, Suisei, Giotto, Vega 1 and 
Vega 2. 
II. Spacecraft Systems 
The ICE spacecraft is a 16-sided cylinder which is 1.61 me- 
ters tall and 1.74 meters wide. Spacecraft mass at launch was 
479 kg which included 104 kg of instruments and 89 kg of 
hydrazine propellant. There are two solar arrays, above and 
below an equipment platform where most of its payload of 
scientific instruments is mounted (Fig. 2). The solar array 
provides for all of the power requirements of the spacecraft. 
The propulsion system is arranged in two independent and 
redundant systems consisting of 12 jet thrusters and 8 fuel 
tanks. This system is used for all spin-rate-change trajectory 
correction, and attitude control maneuvers. The spacecraft 
rotates around the central axis of the cylinder at a rate of 
approximately 20 revolutions per minute. 
The spacecraft carries 13 scientific instruments. Several of 
these utilize appendages to measure conditions near the 
spacecraft without spacecraft intei ference. Magnetic fields are 
measured by two search coils located at the end of two 
3-meter-long booms that extend in opposite directions out 
from the cylinder. Also, long wires, acting as radio mapping 
antennas, extend 92 meters tip-to-tip in the radial direction 
and 14  meters in the axial direction. The experiments aboard 
the spacecraft have directly affected the strategy for targeting 
the spacecraft for its Comet G-Z intercept and Halley radial 
experiment. 
111. Operations 
The DSN utilized the 64-meter subnetwork with stations 
located at Goldstone, California; Madrid, Spain; and Canberra, 
Australia. The 64-meter subnetwork provided nearly con- 
tinuous support from March 15, 1986 to April 15, 1986. The 
subnetwork was used to  collect spacecraft telemetry data, 
send commands to spacecraft, and generate radiometric data. 
Two-way range and range rate data over a 6-week time span 
were utilized by the JF’L Multimission Navigation Team in 
determining the spacecraft orbit relative to  Halley’s Comet. 
The data arc covered the period between spacecraft trajectory 
correction maneuvers performed on February 27, 1986 and 
April 7 ,  1986. 
High quality in situ Halley Comet data was obtained via the 
64-meter subnetwork and sent to the ICE Project located at 
the Goddard Space Flight Center (GSFC) where the data was 
processed and provided to the science investigators. The ICE 
Project was very pleased with the high quality data that was 
provided by the DSN and as a direct result were able to obtain 
excellent day-to-day data correlation for the Halley radial 
encounter period. 
IV. Surprising Results 
Solar plasma flowing radially outward from a rotating sun, 
carries along with it the interplanetary magnetic field (IMF). 
This results in a pinwheel-like structure to  the solar wind. 
For a plasma flowing radially outward at 450 km/sec, Fig. 3 
schematically illustrates the heliocentric orbits of the Earth, 
ICE and Halley relative to IMF field lines at 45’ intervals 
during the six month period from 1 January 1986 through 
1 July 1986. Figure 4 provides three orthogonal projections of 
the ICE orbit in a Halley-centered reference frame. Figure 4a 
shows a projection for an observer above the Halley orbit 
plane, 4b for an observer looking toward the Sun along the 
Halley-Sun line, and 4c for an observer in the Halley orbit 
plane looking toward the Sun-Halley line. In each view the 
circle is the projection of a sphere of radius 35 X lo6 km 
centered at Halley. Due to  the negligible gravity potential and 
weak bow shock associated with comets, neutral heavy parti- 
cles emitted from the nucleus are able to  travel great distances 
in all directions before they are ionized by the Sun’s ultra- 
violet radiation. Once ionized, they are picked up by the 
plasma and begin to gyrate around the field lines. 
Closest approach of ICE to Halley was at a distance of 
28 X lo6 km on 25 March 1986. The minimum Halley-Sun- 
ICE angle of about 6” occurred on 28 March 1986. From 
References 7 and 8, the energetic ion instrument (EPAS) 
measurements aboard ICE appear to be consistent with the 
interaction of the solar wind with heavy ions speculated to 
have their source in Halley’s nucleus. Such an interpretation is 
in agreement with the ICE observations during the Comet G-Z 
encounter period. This implies a Halley’s Comet solar wind 
interaction region extending perhaps 30-40 X lo6 km from 
the comet’s nucleus. Hence, when Halley is 1 AU from the 
Sun, its plasma interaction region extends from near the orbit 
of Venus out to  mid-way between the orbits of Earth and 
Mars. The ICE mission has unexpectedly revealed that comets, 
despite their small nuclei, can have interaction zones near 
perihelion which exceed in size and volume the similar zones 
associated with the heliocentric motion of even the giant 
outer planets. 
286 
References 
1. Efron, L., Muellerschoen, R. J., and Premkumar, R. I., “ICE Navigation Support,” 
TDA Progress Report 42-86, pp. 268-283, Jet Propulsion Laboratory, Pasadena, 
Calif., August 15, 1986. 
2. Fanelli, N. A., and Morris, D. G., “ICE Encounter Operations,” TDA Progress Report 
42-84, pp. 176-185, Jet Propulsion Laboratory, Pasadena, Calif., February 15, 1986. 
3.  Goodwin, J. P., “Usuda Deep Space Center Support to  ICE,” TDA Progress Report 
42-84, pp. 186-196, Jet Propulsion Laboratory, Pasadena, Calif., February 15, 1986. 
4. Gordon, D. D., and Ward, M. T., “Arecibo Observatory Support of the International 
Cometary Explorer Mission Encounter at Comet Giacobini-Zinner,” TDA Progress 
Report 42-84, pp. 197-202, Jet Propulsion Laboratory, Pasadena, Calif., February 15, 
1986. 
5. Layland, J. W., “ICE Telemetry Performance,” TDA Progress Report 42-84, pp. 203- 
213, Jet Propulsion Laboratory, Pasadena, Calif., February 15, 1986. 
6. Hurd, W. J., Pollara, F., Russell, M. D., Siev, B., and Winter, P. U., “Intercontinental 
Antenna Arraying by Symbol Stream Combining at Giacobini-Zinner Encounter,” 
TDA Progress Report 42-84, pp. 220-228, Jet Propulsion Laboratory, Pasadena, 
Calif., February 15, 1986. 
7. Scarf, F. L., et al., “ICE Plasma Wave Measurements in the Ion Pick-up Region of 
Comet Halley,” Geophysical Research Letters, Vol. 13, No. 8,  pp. 857-860, August 
1986. 
8. Wenzel, K. P., et al., “In-Situ Observations of Cometary Pick-Up Ions 20.2 AU Up- 
stream of Comet Halley: ICE Observations,” Geophysical Research Letters, Vol. 13, 
NO. 8 ,  pp. 861-864, August 1986. 
287 
MAY 
0.21 AU TO 
COMET HALLEY 
6O FROM RADIAL 
MARCH 28, 1986 
10-10 / 
8-16 COMET 
COMET HALLEY 
1' FROM RADIAL 
OCT. 31, 1985 
* TO SUN 
PERIHELION 0.93AU 
APHELION 1.03AU 
INCLINATION 0.1 degrees 
FLYBY SPEED AT 
G IACOBI N 1-21 NN ER 
21 kmlsec 
DEPART DEC. 22,1983 
Fig. 1. ICE trajectory relative to a fixed Sun-Earth line 
288 
I 0.1 AU I 
,MEDIUM GAIN 
3D RADIO MAPPING ANTENNA 
LENGTH (TIP TO TIP) 
AXIAL: 1 4 m  
RADIAL: 9 2 m  \ f 2 - G 7  ANTENNA 
SHORT ELECTRIC 
ANTENNA, 
SEARCH COIL 
AXIAL AV 
AND ATTITUDE 
CONTROL 
THRUSTER 
MAGNETOMETER 
RADIAL 
THRUSTERS 
AXIAL AV AND ATTITUDE ,,& I \;"" STABILIZED AT 1975 RPM 
CONTROL THRUSTER 
TOTALSIC WEIGHT 479 kg 
EXPERIMENTS 104 kg 
HYDRAZINE 89 ka 
A SPIN AND OESPlN 
THRUSTERS 
Fig. 2. The ICE spacecraft 
DIMENSIONS (MAIN BODY) 
1.77 m DIAMETER: 
HEIGHT: 1.58 m 
Fig. 3. Heliocentric or%its of ICE, Halley's C O W  and €&h project& oiito the =!iptic plat%?, 
1 Jan. 1986 to 10 July 1986. Time tics are at l W a y  intervals. IYF field lines illustrated 
schematically. 
289 
(a) T 3/15/86 
3/15/86 1. 
Y 
ks"N* X 
411 5/86 
(cl 
z krN 
X 
f 
f 
I f  , r - H A L L E Y  \ 
i 411 5/86 
TIME TICS ARE AT 
1-DAY INTERVALS 
Fig. 4. Halley-centered orbit of ICE (15 March 1986 to 15 April 1986) and the projection of a 35 x lo6 km radius sphere about the nucleus, 
as viewed by an observer (a) above the comet orbit plane, (b) looking toward the Sun along the Halley-Sun line from within the comet tail, 
and (c) in the comet orbit plane looking normal to the Sun-Halley line 
290 


ICE Second Halley radial: TDA mission support and DSN operations

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