Companies who manufacturer space instrumentation (including satellites themselves) have to subject their products to Prototyping, Flight Qualification, and Flight Verification phases. Before launch, the products must experience space-like temperatures and vacuum levels, and be shown not only to survive the extreme ranges, but also to operate within parameters. In order to prove reliable in these multivariable environments, it is required that the unit-under-test is exposed to conditions ranging from launch through altitude increase, then into deep space followed by a re-entry into a specified atmosphere. Space Simulation Chambers are key to these tests, and Abbess Instruments of Holliston, is one of the few companies in the world with the capability and experience to manufacture them.
Abbess Instruments has a wide portfolio of Test systems capable of simulating a variety of space vacuums … with or without heat and/or cooling. Please refer to our Altitude Test Systems page for required testing pressures limited to ≥10-4 Torr (altitudes of up to 250,000 ft / 76km, or more).
A basic Space Simulation Test System (as illustrated in Fig 1) consists of the following:
- Vacuum Chamber
- A front or top-loading Aluminum or SS cube with metal door (in limited cases, an acrylic door).
- Analog Pressure Gauge
Actual chamber material choices are dependent on the desired operational vacuum, as outlined in Table 1.
There are many Upgrade Options available that will add complexity and functionality. These options, including the aforementioned automatic control, are outlined later.
|Material*||Useful Pressure Range (Torr)||Use||Comments|
|Untreated Al with Al or Acrylic door||760 to 10-4 inc.||altitude testing||More powerful pumps will be needed with an Acrylic door than if a metal door was used.
Acrylic door must be kept below 135C.
|Acid-etched Al chamber & door||760 to 10-5 inc.||space simulation|
|Untreated SS chamber & door||760 to 10-6 inc.|
|Electropolished SS chamber & door||10-6 and better|
|Bakeout & Electropolished SS chamber & door||10-7 and better||Bakeout required to outgas chamber|
|* If speed of pumpdown is a priority, consider upgrading to the next material choice|
A complex Space Simulation Vacuum chamber consists of several major subsystems: the main chamber; the pumping system; the thermal shroud; and the control system:
Chambers can be as large as the ones shown above (in the order of 48” x 48” x 48” or larger) and, for vacuums less than 10-5 Torr, are made from electropolished Stainless Steel. Difficult to machine and weld, the chambers are routinely made so that the walls deflect less than an impressive 1/1000” while under vacuum. Thick walls and strategically placed external ribs are needed to do this.
Space Simulation pumping systems are amongst the most complex, often requiring two Turbo pumps in order to bring the expansive chamber down to the required vacuum level … and in a timely fashion. Such pumps attach directly to the chamber and pump through large ports, of around 10” diameter, at speeds of hundreds of cubic feet a minute. A complex pump down is illustrated in Fig 5.
The thermal shroud is a sub-chamber within the chamber finished perhaps in gold (as shown above) to reflect as much heat as possible back to the Unit Under Test; or dense black to absorb as much heat and light as possible. Shrouds are typically heated/cooled sub-systems covering the large range of -80C to +195C, with liquid N2 being the common choice for cooling.
Monitoring and control of systems are attuned to the customer’s specified process needs which, for Space Simulation Systems, usually requires a PC Touch Screen package (the panel is shown to the left of Figs. 2 & 3, and its GUI in Fig. 4) – a necessity when thermal profiling is required. An example of thermal profiling is given in Fig. 6. Manual and automatic valve operation and pump control are configured to both optimize operation time and assure the proper cycling of vacuum equipment. Abbess and system operators can connect remotely to these PC control systems which, in turn, can be programmed to acquire and log data, and to message operator mobile devices.
A sample Complex System Performance Summary is provided in Table 2.Testing is performed on empty, clean chambers at the Abbess Facility in Holliston (188’ elevation).
|Complex Space Simulation System Performance 48” Cube|
|Operational Vacuum||≤10-6 Torr||For an empty, clean chamber at sea level … over all Temp ranges|
|Vacuum Ramps||Pump Down Ramp:
≤10-5 Torr in ≤ 3 hrs
|For an empty, clean chamber at sea level|
|Vacuum Relief Ramp:
< 3 mins
|Deep Space Vacuum Stability||Within 1×10-9 Torr over several minutes
Within 0.2×10-7 over 12h 49m
|Measured at 10-7 Torr|
|Thermal Range||-150°C to +150°C||Of thermal plates|
|Thermal Ramps||Fast Ramp:||Over the range -60°C to +100°C heating and cooling|
|3°C/min||Using 22psi LN2 tanks|
|6°C/min||Using 235 psi LN2 tanks|
Space Simulation Test Systems are readily configured to provide product visibility: Visually observe your test item (illuminated by optional switchable, in-chamber lighting) through optional viewports, as illustrated in Figs 2 & 3. Use the same, or other viewports, to optically illuminate/test your in vacuum items at your desired wavelengths. Close optional shutters for subsequent light-tight storage or functional testing.
Where there is limited counter space or large batch sizes, the entire system can be integrated on a cart using identical or mixed-sized, chambers. Since cart mounted systems are shipped turn-key, set-up is minimal. Cart-mounting provides full system mobility and thus flexibility of positioning on your production floor. Mixed-sized inventory? Add optional removable shelving.
In summary, a Basic Space Simulation Test System (as illustrated in Fig 1) consists of the following:
- Vacuum Chamber
- A front or top-loading Aluminum or SS cube with metal doors.
- Analog Pressure Gauge
Upgrade options include:
- Vacuum Pump with Inlet and Exhaust Filters- Optional power and automatic control can be integrated into a Vacuum Cycle Controller (VCC).
- A Vacuum Cycle Controller (VCC) that can be used to automate some or all of the control functions via panel-mounted buttons and indicators (Fig 2). It will permit a single ‘automatic’ altitude/vacuum set point.
- A VCC controlled by a PC with a user-specified Graphical User Interface (GUI) operated through a touch-screen (as illustrated in Figs 3 & 4 and in Data-Logged High Vacuum Storage System). This permits: automatic monitoring, data-logging, and vacuum environment display; remote access; and optionally message-sending to operator’s mobile device.
- Altitude profile simulation functionality (e.g. ‘Climb & Dive’) can be built in to the PC Touch Screen VCC upgrade option. Such functionality is valid only for altitudes of up to 100,000 ft / 19miles / 30km (pressures ≥10-4). See Altitude Test
- Systems for more details on ‘Climb & Dive’.
- Process Control Enclosure – Contains components necessary for controlling the system as well as logic and interfaces for the
- Vacuum Cycle Controller.
- Process Timer Control
- Status Indicators – Provide visual indication of system status.
- Vacuum Cycle Controller – Control ON/OFF buttons, main power switch.
- Control Valves are required with a VCC:
- Automatic Vent Valve – Automatic solenoid valve vents air or inert gas purge into chamber based on control input from Vacuum Cycle Controller.
- Proportional Valve – controls pumping to a certain rate for altitude profile simulation.
- Digital Pressure Gauge & Controller are required with a VCC
- Provides pressure display and set point valve control per integral Pressure Transducer data. Also provides pressure set-point relays that can be used for various system control functions.
- Mobile cart; or heavy duty in-built casters for the largest systems.
- Heating and/or cooling thermal plates/shelving and control:
for heating up to 150C, or 300C) (as illustrated in the Vacuum Oven System).
and/or for cooling to -150C.
- Shelving (passive).
- Inert gas purge.
- Circulation fans.
- Mechanical feedthroughs such as shafts with or without rotation.
- Electrical feedthroughs for power and signals.
- Optical ports for optimal transmission of test equipment wavelengths
- Special coatings such as gold (e.g. for thermal shroud as in Fig. 2).
- Switchable, internal lighting
- Viewports / optical test ports (see Figs 2 & 3)
Abbess can help you. Successfully test your high-value inventory in our manual or automatic Space Simulation Systems.