The va cuum  enviro nment  is al so considered an impedim ent for d evices that re quire gas-dyna mic  dampin g because the  higher Q (frequency of reso nance/ba ndwidth of resonance) ma kes ele ctronic  feedba ck more difficult.3 Howeve r, we b elieve that the red uced damping an d higher Q in vacuum can b e  used to a dvantage in  reducing required  actu ator volt ages and thu s power and power supply com plexity.  Becau se mass and po wer are tightly con strained i n spa ce application s, high er Q s and lo wer d riving  voltages could become a signifi cant advantage  for many su ch ap plications. Additi onally, some   appli cation s such a s RF filters and p recision resona nt freque ncy m easure ment are imp roved  by higher Q   device s. 

MEMS for Space Applic ations 

MEMS have  begu n to revolutioni ze sensor and control syste ms technology in the n ew millen nium.  Miniaturi zation of such fun ctions is allo wing the silicon revolutio n of the past several de cades to extend  and grow p ast the simp le informatio n handlin g of modern co mputing an d into all aspects of ou r  techn ology-driven lives. Thi s is be cause the input s (sensors) and outputs (contro llers) a re the bottlene cks  that limit many everyd ay techn ology appli cations, particula rly appli cation s where dense nets of  informatio n or control a re neede d. 

Since future satellite missi ons will be limited to sma ll, low mass, low power co nsum ption, and low cost  instru mentati on, in strum entation based around MEM S based tech nology are extremely attractive. MEMS  device s are prod uced usi ng the sam e techni ques that have b een devel oped by the semi-cond uctor  industry to produ ce Inte grated Circuit s. On ce the  initial devel opment of t he fabri cation pro cess is  compl eted, m ass pro duction of duplicate  devices becomes very si mple and in expensive. 

MEMS devices are intrinsi cally small and light. Typica l minimum d imensi ons that are ea sily prod uced on   MEMS devices to day a re ap proxim ately 1 µm. De spite th eir diminutive size, MEMS  devices are  surpri singly strong. T he p rimary mate rial used in the process, p olysilicon, ha s an ultimate  stre ngth i n  tensio n that i s nearly 4 tim es that of steel, but ha s about a third of the den sity. Tanne r et al (2000) te sted  MEMS devices survivabilit y to vibratio n loads. They tested t heir devices with a white noi se spectrum with  a freque ncy range fro m 20 to 2000 Hz with a power spectral d ensity of 0.8 g/H z, 40g RMS. At these high  levels, they had 90% of tested device s pass and still functio n properly.     MEMS Vacuum Test Facilit y 

We have  designed  and developed  a va cuum  microprobe te st facility at the So uthwe st Research Institute   (SwRI) sp ecifically to enab le the develo pment, test ing, and long term, in-va cuum, evaluatio n of MEMS  device s for space a pplications4. To the best of our knowl edge, the SwRI facility is uni que in that it  provide s the full functional ity of a  flexib le, well in strumented mi cropro be statio n within a hi gh vacu um  environment. The S wRI vac uum tes t facility, s hown in Figu re 1, has  been  developed to allow flexible and  compl ete test ing of MEMS device s while  keepi ng the m continu ously within a hig h vacuum e nvironme nt. 

The centerpi ece of this fa cility is our m icro-manipul ated vacuum microprobe station.  Fitted to four of the  ports are p robes attache d via movabl e bello ws to  x-y-z mi crometer mi cro positio ning stages. Stage   motion is 5 µm per full tu rn in the late ral dire ction s and 1 2 µm per turn in the  vertical di rection providi ng  positio n control of the mi cropro bes to <<1 µm. This fi ne mani pulat or control allows us to man ually actuate  the mi cromechanical devices if  needed in addition  to the basi c function of provi ding input voltages to the  variou s pad s.   180