Experiment Operations During Apollo EVAs

Experiment: Suprathermal Ion Detector Experiment

a.k.a. Lunar Ionosphere Detector
Acronym: SIDE


The Apollo 14 SIDE after deployment. Note the dust adhering to the vertical surface of the unit (AS-14-67-9371). The ground screen is visible below the unit. The bubble level and sun orientation arrow are also visible on the top at the right side. See attachment of the CCG to the SIDE.

The SIDE instrument deployed at the Apollo 15 ALSEP site. Its greater tilt is due to the higher latitude of the Apollo 15 landing site (AS-15-86-11595).

PI/Engineer: John W. Freeman, Rice University
Other Contacts:
H. Balsiger, Rice Univ.
H. K. Hills, Rice Univ.
Dallas E. Evans, JSC

Apollo Flight Nos.: 12, 14, 15
Apollo Exp't No. S 036

Discipline: lunar atmosphere, solar wind, radiation, lunar vulcanology, Earth Sciences-magnetosphere, human environmental impact on the moon

Weight: 8.5 - 8.8 kg
Dimensions:
38.9 x 33.0 x 11.4 cm. When deployed, the top surface stood 51 cm above the lunar surface.

Manufacturer: Time Zero Corp. (formerly Marshal Laboratories)

Description/Purpose:
The SIDE consisted of two positive ion detectors. The first, the mass analyzer, was provided with a velocity filter and a curved plate electrostatic energy-per-unit-charge filter in tandem in the ion flight path. The second, the total ion detector, employed only a curved plate electrostatic energy-per-unit-charge filter. The only major difference between the instruments on A-12, 14, & 15 was the mass range they covered.

The purpose was to (1) provide information on the energy and mass spectra of the positive ions close to the lunar surface that result from solar-UV or solar-wind ionization of gasses from any of the following sources: residual primordial atmosphere of heavy gasses, sporadic out-gassing such as volcanic activity, evaporation of solar-wind gasses accreted on the lunar surface, and exhaust gasses from the lunar module descent and ascent motors and the astronauts' PLSS's. (2) Measure the flux and energy spectrum of positive ions in the Earth's magnetotail and magnetosheath during those periods when the Moon passes through the magnetic tail of the Earth. (3) Provide data on the plasma interaction between the solar wind and the Moon. (4) determine a preliminary value for the electric potential of the lunar surface. By having more than one instrument on the surface, discrimination is possible between moving ion clouds and temporal fluctuations of the overall ion distribution.

Unloading from the LM: As part of ALSEP

Transporting by foot or MET: As part of ALSEP
On A-12, the SIDE was carried separately from the rest of the ALSEP package. Once at the ALSEP site it was carried with the UHT.

Loading/unloading tools/exp'ts on LRV: NA

Site selection: As part of ALSEP
The SIDE was deployed 15 to 18 m NE of the central station, limited by an 18 m cable. The site was smooth and allowed emplacement of the ground screen.

Deploying experiment:
Its 3 legs had to be unfolded and a cable connected to the central station. The instrument was grounded to the surface via a screen. The CCIG was stored inside the SIDE for transport, then separated from it before deployment (but it remained connected by a cable ~1 meter long).

It was carried to its site with the UHT. The UHT was then used to release the ground screen, which was then emplaced on the surface. The CCIG (which see) cover Deutsch fastener was then released with the UHT and the entire SIDE/CCIG package was lifted using the UHT. The CCIG cover was removed and discarded. The CCIG was removed from its stowage cavity and the SIDE was replaced on the surface on its ground screen. A lanyard was used to lower the CCIG to the surface. The CCIG orifice was oriented properly. The SIDE was leveled and aligned by observing the shadow on the side of the unit. A typical timeline from A-15 shows ~10 minutes for deploying the experiment, including the CCIG.

On A-12, the protective lid, designed to be released by ground command, opened accidentally 3 times during deployment and had to be re-closed. It was left open the last time since the experiment was already deployed. It took both crew working together to orient both the SIDE and the CCIG due to the force of the cable between them. The CCIG was not placed as far from the SIDE as it should have been because the force of the cable disallowed it.

On A-14, considerable difficulty was experienced with the stiffness of the interconnecting cable between the CCIG and the SIDE. Whenever an attempt was made to move the CCIG, the cable caused the SIDE to tip over. It tipped over 3 times. After several minutes of readjusting the experiments, they managed to deploy them successfully, although a large amount of dust adhered to one end of the package. A similar problem was seen on A-12 which caused the CCIG to be deployed at an angle (see CCIG.) On A-15, the connection to the SIDE was redesigned to be an "extended leg" based on the above experience and because of the high latitude of the site vs. its intended field of view. Also on A-14, 10 minutes were required to release the SIDE from its subpallet since dust had piled up against it and into the hidden Boyd bolt, which had to be reached blind by passing the UHT through a channel. The three components of the experiment were difficult to handle simultaneously, and they were not sufficiently stable to prevent the SIDE from turning over several times during deployment. On A-15, there was some difficulty in interfacing the UHT with the experiment receptacle and, as a result, the instrument was dropped, apparently with no harm.

Check-out of experiment: from Earth.

Operation of experiment:
From JSC via the ALSEP command system. On A-14, the high voltages were not operated when the instrument was above 25deg C on the lunar day of deployment, 45deg C on the 2nd lunar day, 55deg C on the 3rd, working up by 10deg C each lunar day until full time operation was reached. This protocol was based on observations of high gas levels near lunar noon on the A-12 instrument and was controlled from Earth.. Dust in the A-12 instrument from deployment by the LMP may also have been a cause of the problems.

Repairs to experiment:
See deployment. On A-14, the crew had to turn the unit upside down to knock the dust out and be able to release the Boyd bolt. On A-15, con-nection of the SIDE to the central station was very difficult. It required the LMP to use both hands and all the weight that he could bring to bear on the locking collar.

Recovery/take-down of experiment: NA

Stowing experiment for return: NA

Loading/unloading samples on LRV: NA

Loading of exp't/samples into the LM: NA

Stowing of package once in the LM: NA

Sampling operations - soil, rocks: NA

Trenching: NA

Raking: NA

Drilling: NA

Coring: NA

Navigating/recognizing landmarks: NA

Were there any hazards in the experiment?
i.e. hazardous materials (explosive, radioactive, toxic), sharp objects, high voltages, massive, bulky, tripping hazards, temperatures?
The high voltage of the instrument was not activated until after deployment.

Was lighting a problem? No.

Were the results visible to the crew? No.

Would you recommend any design changes?
The original design was for the CCIG to be totally included in the SIDE package, but its magnetic field interfered with the SIDE instrument and the two packages needed to be separated. The A-12 crew commented that the 3 legs were too close together, which made it prone to tipping over. They also had a hard time with the spring-loaded ground screen, recommending that the spring-loading be left out. The A-14 crew suggested leaving the blind Boyd bolt off to ease release from the sub-pallet.

Were any special tools required? UHT

Was the orientation of the experiment (i.e. horizontal/vertical) important? Difficult?
Difficult, due to the interconnecting cable to the CCIG. The orientation of the instruments was to align the "look" direction with the direction of the magneto-sheath around the Earth as the moon entered and left this region each month. The "look" directions of A-12, 14, & 15 were oriented differently to cover a wide range and allow study of the directional characteristics of ion fluxes. The astronaut leveled the unit to within 5deg of vertical using a bubble level. It also needed to be within 5deg of E-W alignment by pointing an arrow at the sun and then aligning a shadow with the side of the unit.

Was the experiment successful? Yes, alone and in coordination with the other sights.

Were there related experiments on other flights? See CPLEE (S038)

Where was it stored during flight? With the ALSEP subpallet. The CCIG experiment used some of the electronics of the SIDE experiment.

Were there any problems photographing the experiment? No.

What pre-launch and cruise req'ts were there?
power, thermal, late access, early recovery?

What was different between training and actual EVA? Low g allowed the units to tip over.

What problems were due to the suit rather than the experiment?
Hard to manipulate the CCIG and SIDE and the ground screen all at once in the EMU.

Any experiences inside the LM of interest from the experiment/operations viewpoint?
The exhaust gasses of the LM descent and ascent engines and the PLSS's were detected by the SIDE. Venting of the LM cabin oxygen before the 2nd EVA provided a convenient calibration of the mass analyzer detector.

References:

Preliminary Science Reports, A-12, 14, 15

Mission Reports, A-12, 14, 15

Apollo Scientific Experiments Data Handbook, JSC-09166, NASA TM X-58131, August, 1974, In JSC History Office.

Final Apollo 12 Lunar Surface Operations Plan, JSC, October 23, 1969

Apollo 14 Final Lunar Surface Procedures, JSC, December 31, 1970.

Apollo 15 Final Lunar Surface Procedures, JSC, July 9, 1971

Apollo Program Summary Report, section 3.2.23 Suprathermal Ion Detector and Cold-Cathode Gage Experiments, JCS-09423, April, 1975.

Apollo 14 Technical Crew Debriefing 17 February 1971.

ALSEP Termination Report, NASA Reference Publication 1036, April, 1979.