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Space DeployablesPrinciples of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Spacecraft Deployables

• Deployable applications• Mechanisms

• This material developed by Rodger Farley for ENAE 691 (Satellite Design)



Applications• solar arrays• sun shades• solar sails• antennas• reflective concentrators (mesh and solid)• radars• optical metering structures (telescopes,

interferometers), full and sparse apertures• boom instruments: magnetometers, e-field

measurements• orbital dynamics (gravity gradient)• momentum transfer (yo-yo despin , 2-point

tethers)• large assemblies (space stations , complex

observatories)



Methods• rigid articulating booms• articulating lattice masts• coilable lattice masts• telescoping booms• wire booms (centrifugal stiffening)• stacers• foldable trusses• pop-up trusses• foldable panels• inflatable structures• foam structures• free-flying formations• 2-point tethered objects (orbit transfer,

electricity generation)• large rotating tethered formations



Deployment Devices (page 1)


















RAE• RAE used STEM (structural

tubular extendible mast) booms to create antennas as long as 229-m. The spacecraft’s spin stabilization was reduced using yo-yo despin throw-away masses.

Lunar orbit

1973

Also known as the ‘DeHavilland’ boom, developed in 1947

Sunlight on one side created bowing. STEMS now use perforated holes to illuminate backside-inside, which can be coated black.Manufacturing capability limited, needs continuous processing technology for heat treatment, and perforations and coatings. Materials include BeCu and S.Steel.



SEASAT / RADARSAT

• Synthetic Aperture Radar on an extendible support structure

• 1mm flatness over 15m length

RADARSAT 1995



Jumpseat, Trumpet large collectors

Wrap-rib unfurling parabolic mesh collector, 20 – 50 meters in diameter. Placed in 12hr Molniya orbits. The wrap-rib design has structural ribs wrapped around a central hub, then it unwraps at deployment. I imagine this is a very expensive way to do this.

SIGINT spy satellites from the 1970s, Trumpets replaced them in the 1990s



TDRS solar array, antenna

Older series TDRS. Single Access antennas on the TDRS. The Harris deployable mesh antennas are 4.9 meters (16ft) in diameter. Similar antenna was used on GALILEO (it failed to open properly)

The solar arrays used a kapton facesheet , with holes cut out in the back facesheet over each honeycomb cell for radiative cooling. Newer series TDRS using the ‘taco shell’

composite antenna

TDRS-A 1983

Manufacturing limitations for thin composite shells are the thermal gradients developed in the tooling during curing; this warps the shape into a ‘potato chip’.



Solar Array Flight Experiment

• Use of 34m nut-deployed coilable longeron lattice mast, 1987

• Flexible z-fold solar array blanket

Precursor to the ISS arrays. 426 kg



SRTM

• At 200 feet, the SRTM ADAM™ Mast is the longest man-made hardware to ever fly in space. In comparison, the Russian Space Station, Mir, was 108 feet in length, 98 feet in width, and 89 feet in height. The first U.S. space station, Skylab (1973-74), with the Apollo Command Module attached, measured 134 feet in length by 22 feet in diameter (90 feet with solar arrays open).

2 / 2000

Articulated lattice mast, longest deployable truss to ever fly. Tip stable to 10mm



MilStar• 10000 lbs, Titan IV, geostationary

• Unfolding truss structure and 16m astromast

1994, 1995,1999

8.5 kw each wing, at 88kg. This works out to 97 watts per kg, standard technology is 30 watts per kg. S/A similar to SAFE, ISS



Wirebooms and stacers

• Spinning spacecraft with radial and axial booms

FAST 1996

3m stacer booms

IMAGE 2000

250m long wire booms, ¼ rpm

IMAGE was the longest wire boom to fly, ½ km in diameter. The wires were let out very slowly in stages. When short, the dog wags the tail, but as it gets longer, the tail starts to wag the dog. It’s as if the wires are springs reaching out from infinity, giving the core s/c ‘washing-machine cycle’ modes. One wire broke after ~4 months in orbit,

due to debris impact.



TSS-1R• The tether reel mechanism controls

the length, speed, and tension of the tether. The tether reel carries 22 km (~14 miles) of conducting tether. When the satellite is fully deployed, and the tether conductor is pulsed by electron accelerators, the TSS will be the longest and lowest frequency antenna ever placed in orbit. The tether broke at 20 km during the mission in 1996.

• There maybe ~ 100m2 of exposed tether, so the probability of debris impact is high.

• Think of it as 20km of single point failures Tether mission deployed from the top

of an ABLE fastmast



Early inflatables• The Echo 2 spacecraft was a 41-m

balloon of aluminum foil-mylar laminate. Echo 2 was designed as a rigidized passive communications spacecraft for testing propagation, tracking, and communication techniques.

1964 – 1969Rigidization techniques today: Stretched aluminum foil, passes yield

and removes wrinkles Glass transition going cold for

neoprene coated Kevlar Water evaporation (corn-starch) Heat curing pre-preg gr/epoxy Glass transition for cured epoxy

Inflated to milli-psig. The aluminum foil is rigidized when all the wrinkles are stretched out, just past the yield point. One blew-up in the high-bay, knocked the pictures off the wall. Inflation techniques are compressed gas, and ‘blowing agents’ as in an automobile airbag.



Recent inflatables• Inflatable Antenna Experiment • The Spartan spacecraft was

rectangular in shape before the antenna inflation. The IAE occupied about half the volume and the support systems occupying the rest. The IAE is an inflatable antenna 50 feet (14 meters) in diameter mounted on three 92-foot (28 meter) struts.

1996

The lenticular antenna did not inflate. Residual gas partially popped it out of the box before it could be kicked out to impart deployment momentum.



Thuraya, INMARSAT-4• 12-meter TRW AstroMesh reflector

deployed in a manufacturing high bay. The reflector is one of the largest developed for satellite communications applications. When stowed, the reflector folds into a compact package only 10 percent of its full diameter.

Thuraya 2000

INMARSAT-4 future

Geo-tensoid antenna, but low frequency of single boom attachment is a problem.



Mars Surveyor 2001 Lander • Lander mysteriously canceled• UltraFlex is a “fan-folded” flexible

solar array that deploys to form a tensioned ten-sided polygon. Photovoltaic cells are bonded directly to the flexible substrate, minimizing complexity and mass. The Mars Surveyor 2001 wings, each with a diameter of 2 meters, can deploy in a 1 “g” field and produce in excess of 105 watts per kilogram.



NGST deployable optics, deployable sun

6.25m passively-cooled optics, re-scoped from 8m. Tennis-court sized sun shield

TRW / Ball version

Lockheed-Martin version

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