What is this balloon doing in this clean room and what is the proper name for the "stand" (white & blue) that is holding the satellite?

  • $\begingroup$ Pretty sure the stand is a vibration tester. No idea what the balloon is for, huh. $\endgroup$
    – PearsonArtPhoto
    Commented Feb 6, 2019 at 3:21
  • $\begingroup$ No that is not for vibration test. This is >> isac.gov.in/facility/f-system-3.jsp $\endgroup$
    – keshto pat
    Commented Feb 6, 2019 at 6:52
  • $\begingroup$ I'd call that a goniometer, but there may be a fancier name for it. $\endgroup$
    – uhoh
    Commented Feb 6, 2019 at 9:04

2 Answers 2


The balloon is used to support parts of the spacecraft that can't hold their own weight in 1 g - booms, appendages, etc.

As you can see from this cropped photo (from here), there is no hose to allow flowing extra gas into the balloon. It is simply connected to the object it supports by a tether.enter image description here

The stand is called a "positioner" if it allows the spacecraft to be held at multiple angles. But often just referred to as "fixture" or "stand".

A 3-axis positioner can also be used. This is an elaborate fixture that holds the spacecraft at multiple angles to measure all mass properties (CG in 3 axes, MOI in 3 axes, and POI in 3 planes). It allows calculation of product of inertia based on moment of inertia measurement, so the entire inertia tensor can be derived with the use of a KSR instrument. The spacecraft positioner also minimizes handling of the spacecraft. The spacecraft is mounted in a vertical orientation; the positioner rotates the spacecraft to the various measurement positions and brings the spacecraft back to vertical for easy dismounting.

More, and examples here


Having looked at the various ISAC facilities, I suspect that is just an adjustable stand in one of the clean rooms.

Compare to this image search result for 'ISAC clean room':

enter image description here

The stand is adjustable to give easy access to all areas of the satellite without having to use ladders (which can fall over and damage the satellite).

A similar system (with only 1 degree of freedom) for car bodies is known as a rotisserie: enter image description here

ISAC has removed all images of their test facilities from the HTML of their website, but the images are still there and can be found via an image search.

Example, this is a vibration test system at ISAC:

enter image description here

As for the balloon, I haven't found a reference. I suspect it's used to capture overflow helium during filling of the helium tanks in a spacecraft.

  • $\begingroup$ Maybe the helium tanks are "washed" from remaining air by filling them partially and then releasing the mix of helium and air into the balloon until there is only pure helium in the tanks. $\endgroup$
    – Uwe
    Commented Feb 6, 2019 at 9:35
  • $\begingroup$ Of course, as we've learned previously, it doesn't prevent damage to the satellite if you forget to bolt it down: space.stackexchange.com/q/1783/58 $\endgroup$
    – called2voyage
    Commented Feb 6, 2019 at 14:49
  • $\begingroup$ With reference to this statement "Having looked at the various ISAC facilities..." Are you currently working at ISRO? Sorry to ask an irrelevant question, but it is related to one of my questions. $\endgroup$
    – Vishnu
    Commented Oct 23, 2019 at 13:25
  • 1
    $\begingroup$ No. I only did an image search on the internet. $\endgroup$
    – Hobbes
    Commented Oct 23, 2019 at 13:36

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