ASCS/NCS Relay Unit Breaker Assembly

(ARUBA)


Introduction

One of the most important instruments on the Hubble Space Telescope, called NICMOS, stopped operation in January 1999.  In order to revive it, NASA decided to build and install a super refrigerator that will cool the instrument back down to about 78 K (degrees above absolute zero).  The NICMOS Cooling System (NCS), which will be installed during the SM3B Mission in the spring of 2002, consumes so much power that it is connected directly to the six batteries on HST.

In early October 2001, the HST engineers realized that there could be a problem with the system.  A certain failure in the NCS system could drain all six batteries, and there would be no way to disconnect from the spacecraft.  The HST Project decided that a solution was needed to interrupt the power so that the on-board computers could shut down the system in time.  A small team was quickly assembled (that I would head up) to fix this problem by building a small relay box which would be installed on the external radiator.

I chose the acronym ARUBA in order to stimulate excitement and interest among the people (and especially the school-aged kids) of Aruba for this upcoming mission.  It represents a first for our history (in my opinion) to have the island's name go into space with such an important role.  My objective is to create interest for education in the sciences and engineering among the students.
 

Location

The ARUBA will be mounted right where power is connected to the NCS system.  This occurs outside of HST on the external radiator.


Due to the high power consumption of the NCS, we will have to install a radiator outside of HST.  Here it hangs on the HFMS
Hubble Simulator for a fit check.  The ARUBA will be located on this radiator, so will be visible from the outside of HST.
After the astronauts install the radiator, they will use a cable to power up the ARUBA, and the rest of NCS.
The loop of cable in the drawing on the left is the cable the astronauts will be plugging into ARUBA in the future.


Three dimensional drawing of a preliminary version of the ARUBA mounted on radiator.
It is the item in the corner of the grid of holes on the radiator, and will house three relays.
Later, we added a third connector to the top of the box.


Within a few days of the concept being generated, we were already training the astronauts to use the ARUBA
in the NBL tank.  This is where astronauts train underwater to simulate the zero G of space.
Since the astronauts need to interact with it, this nonfunctional mockup is to evaluate proper reach and
access.  It is marked with the blurry red 'X'.  Here, the astronaut has just plugged the cable
coming from HST that provides power into the ARUBA.  The code in the top right
means Day-of-Year 283 (Oct 10), at 15:22 or 2:22pm.  The bottom numbers identify the camera.


Construction of the ARUBA


After several weeks of hard work by the mechanical designers and the fabrication facility, the flight unit is ready.
Two views of it are shown here.  The connector on the side (J3) has the control cable connection,
while power input is on top (J1).  This latter connector is where the astronauts mate to the HST.


The first test we perform on the flight unit is the vibration test, where they are shaken at 12 G's of accelleration on a
table such as this.  This simulates the shock of launch on the shuttle.  The whole system becomes so LOUD that
you can not stand next to the table without hearing protection.



Since the vibration table moves in one direction only (like a speaker cone) -- in the vertical direction in this case,
the flight hardware (ARUBA and its two controller boxes) are mounted on a plate that can be
put in different positions.  In these pictures we see the test in the X direction, and then the Y.
Lastly, we test in the Z direction (not shown).


Before the test, we place sensors on the flight unit to measure how much it shakes during the test.
The picture here shows Vick mounting these 'accellerometers'.  Note one is visible on the top
between the three connectors with the thin black cable.  These sensors allow the engineers to
monitor to make sure that nothing shakes out of control.


Here is the ARUBA in the blanket shop with its template on.  Since the box will sit outside of HST, it will need to
be protected from the environment of space.  This will occur with a Multi Layer Insulation (MLI) blanket.
The template, made of clear plastic, is a tool that is used to make sure the blanket is of the correct shape.
The connector that will be mated by the astronauts is the left most one on the top of the box.
 

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