Developm ent of a Strain Energy Deplo yable Boom   for the Space Techn ology 5 Mission  

Stew Meyers* and Jam es Sturm*  

The ST-5 Mi ssion 

The Sp ace T echnology 5 (ST5) mi ssion is on e of a series of te chnology demo nstratio n mission s for the  New Millenni um Program. This missi on will fly three fully functional   25-kilog ram micro-cla ss spacecraft in formatio n thro ugh the Earth ’s  magneto sphere; the p rimary scie nce instrume nt is a v ery se nsitive  magneto meter. The con straints of a 25 -kg “Micosat” resulted in a   spin stabili zed, octago nal spacecraft that is 30 cm tall by 50 cm   diamete r and  has state -of-the-art solar cells on all eight side s. A  non-mag netic boom  was n eede d to place the m agnetometer a s far  from the spa cecraft and it s residual magneti c fields as possibl e.  The ST-5 spacecraft is de signed to be spu n up and relea sed from  its depl oyer with the boom and  mag netometer sto wed fo r later  relea se. The depl oyer is the topi c of anothe r paper. Thi s paper  descri bes the develo pment efforts and resultin g self-de ploying  magneto meter boom.  Figure 1.  ST-5 Space craft  Boom Deplo yed Figure 1.  ST-5 Space craft  Boom Deplo yed 

Deployed re quirements  • The sp acecra ft shall inclu de structure an d mech anisms that deploy the magnet ometer sen sor away  from the vehi cle central b ody.  • The mag netometer sen sor shall b e at least 1.5 spacecraft diam eters away from the ce ntral bo dy.  • The mag netometer alig nment to the spa cecraft coordi nate syste m after deploym ent shall b e  repeatable to within 0.25 d egree of nomi nal orie ntatio n and withi n 1.0 cm of no minal dista nce.   • The natu ral freque ncy of the deploye d structu re for the magneto meter shall b e betwee n 5 and  11Hz.  • Any initial disturba nce on th e deploye d structu re shall be red uced b y 95%, as measu red as the peakto-pea k displacement at the magneto meter sen sor head, within 20 seconds of th e impulse.  • The sp acecra ft shall be de signed so tha t generate d electric and/o r magneti c fields do n ot interfere  with magn etometer mea surements.  • Space craft-in duced mag netic fields a s measure d at the magneto meter sen sor location sh all be  less  than 10.0 na no Tesla (D.C.), and less th an 0.5 nan o Tesla (A.C., at 200Hz). 

Stowed requi reme nts  • Coupled Rigid Natural Fre quen cy sh all be gre ater th an 50 Hz.  • Fixed-b ase Natural F requency sh all be g reater than 1 00 Hz.  • Deploying Torque M argin shall be at least 2:1 (GEVS)  • Design L oads shall be 1 6G in each axi s indep ende ntly  • Mass bud get for the magn etometer b oom, without magnetom eter sensor head element s shall be less  than 750 g  • Survival temperatu re limits shall b e from -80°C to +70° C  • Operating te mperature lim its shall b e from -55 °C to +50°C  (These temp eratu re limits are und er review be cause of the sh ift from a seco ndary pa yload on a   Delta/Atlas cl ass laun ch ve hicle to a pr imary payloa d on a Pegasu s laun ch vehi cle.) 

                                                            * NASA Goddard Spac e Flight Center, Greenbelt, MD 

Procee dings of the 37th Aeros pace Mec hanisms Sy mpos ium, Joh nson S pace Ce nter, May 19-2 1, 200 4  73