उपग्रह

[[chitr:Aryabhata-Satellite.jpg|thumb|250px|upagrah aryabhat]] upagrah (aangrezi: Satellite) kisi bhi grah ke charoan or parikrama karane vale piand ko kahate hai.

antariksh u dan ke sandarbh mean-

upagrah ek vastu hai, jise manav prayas ke dvara kaksha mean sthapit kiya jata hai. is tarah ki vastuoan ko prakritik upagrahoan jaise chandrama se alag karane ke lie kabhi-kabhi kritrim upagrah bhi kaha jata hai.

• chandrama prithvi ka prakritik upagrah hai jabaki ianset-bi prithvi ka kritrim upagrah hai.
• upagrah ki kakshiy chal kakshiy trijya par nirbhar karati hai. prithvi tal ke ati nikat chakkar lagane vale upagrah ki kakshiy chal lagabhag 7.9 ya 8 ki.mi./se. hoti hai.
• prithvi ke ati nikat chakkar lagane vale upagrah ka parikraman kal 84 minat hota hai.
• bhoo-sthayi upagrah prithvi tal se lagabhag 36000 ki.mi. ki ooanchaee par rahakar prithvi ka parikraman karata hai. bhoo-sthayi upagrah prithvi ke aksh ke lambavat tal mean pashchim se poorab ki or prithvi ki parikrama karata hai tatha isaka parikraman kal prithvi ke parikraman kal (24 ghante) ke barabar hota hai.
• kritrim upagrah ke andar pratyek vastu bharahinata ki sthiti mean hoti hai.

upagrah grah ki parikrama karanevale akashiy piandoan ko upagrah kahate haian. chandrama bhi prithvi ka upagrah hai. apane grahoan ki parikrama karane mean upagrah ek nishchit kaksha mean, nishchit veg se, ghoomate haian jisase pratyek sthan par apakeandr bal, gurutviy bal ke barabar aur usake viparit ho jata hai.

yadi kisi upagrah ka dravyaman m hai jo M ke ek grah ke charoan or v veg se ghoom raha hai aur usaki vrittakar trijya r hai to

apakeandr bal=akarshan

ya jisamean G gurutvaank hai,

ya

ya v₂ R=G M. jo ek niyantak ke barabar hoga.

prithvi se chandrama 3,80,000 ki.mi. door hai aur usaka veg ek ki.mi. prati sekand ke lagabhag hai jo prithvi ke pas ke upagrah ke veg ka keval 1/8 hai. at: chandrama ek mahine mean prithvi ki parikrama poori karata hai jab ki prithvi ke pas ka upagrah ek din mean 15 parikrama kar leta hai.

kritrim upagrah-yadi kisi manavanirmit upagrah ko prithvi ki parikrama karane ke lie aantariksh mean bhejana hai to usake lie kam se kam 8 ki.mi. ya 5 mil prati se. ka veg avashyak hai. is veg ko pratham aantariksh veg (First comic velocity) kahate haian. yadi veg 11.2 ki.mi. prati sekand ho jay to vah dvitiy aantariksh veg ya palayan veg (escape velocity) kahalata hai. upagrah is veg dvara prithvi ke akarshanakshetr se bahar ho jaega tatha saur mandal mean anyatr chala jaega.

palayan veg vah kam se kam veg hai jisase kisi vastu ko prithvi ke oopar ki or pheankane par vah vastu ki gurutvakarshan sima se bahar nikal jae aur phir lautakar prithvi par vapas n a sake.

ise nimnasootr se jnat karate haian-

jahaan v= vastu ka palayan veg

G= gurutvakarshaniy niyataank =6.66´10-8s.g.

s. matrak

M=prithvi ka dravyaman 6´1027 gram

R=prithvi ki trijya 6.4´108 semi

in manoan ko samikaran mean pratishthapit karane par-

v= 1.1´106 semi/se.

11 kimi prati se. ya 7 mil prati se.

36000 phut/se. ya 25000 mil prati ghanta lagabhag.

tivragami jet vimanoan aur raketoan ka avishkar hone se kritrim upagrahoan ko aantariksh mean bhejane tatha any grahoan par aantariksh yanoan mean jane mean suvidha ho gee. 4 aktoobar, 1957 ko roos dvara chho da gaya kritrim upagrah ek svachalit roket tha jo bahusteji raket se poorvanirdharit kaksha mean chho da gaya tha. sputanik ke sath hi usako le janevala raket bhi prithvi ki parikrama usake lagabhag 1000 ki.mi. ki doori par tatha lagabhag usi ooanchaee par karata raha aur aant mean ghane vayumandal mean pravisht hone se jalakar rakh ho gaya.

upagrah ko prithvi se kitani ooanchaee par paribhraman karana chahie isapar koee ek mat nahian. keval janane yogay bat yah hai ki jitana hi vah prithvi ke sannikat rahega utani usaki gati tej hogi aur utane hi shighr vah apani parikrama poori karega. 2,39,000 mil ki doori par bhraman karanevala chandrama keval 2,400 mil prati ghante ke hisab se paribhraman karata hai aur is parikrama mean use 27 din se adhak lagate haian, kiantu 560 mil ki doori par chho da hua roosi kritrim chandrama apani parikrama 18,000 mil prati ghanta ki gati se 96 minat mean hi poori karata tha. yadi yahi upagrah 1,075 mil par paribhraman karata to isaki gati 15,000 mil prati ghanta hoti aur vah apana chakkar do ghante mean samapt kar leta. vaijnanikoan ki yojanaoan se yah maloom p data hai ki upagrah 300 mil se lekar 1,000 mil tak ki doori par hi chho de jaean taki prithvi ke vayumandal se bahar hone ke karan vayumandal dvara gati avaruddh n ho aur kisi prakar shakti vyay n ho, sath hi nikat hone ke karan uday aur ast honevale soory ki kiranoan mean inaka paryavekshan bhi ho sake.

kaksha mean bhraman karanevale kisi prakshepatr ko prithvi ke gurutvakarshan se bahar rahana p dega, yah mithya dharan hai, kyoanki siddhaantat: akarshan ka prabhav anant tak jata hai. paridhi mean bhraman karanevala upagrah isalie pradakshina karata hai ki is paridhi par prithvi ka gurutvakarshan (gravitaiton) aur paribhraman ke karan utpann apakeandrak bal (cetntrifugal force) barabar ho jate haian. prithvi ki vakrata ke karan vah upagrah ban jata hai.

yahaan yah prashn bhi uthata hai ki upagrah ko kis kaksha mean bhraman karana chahie. vijnan ke anusar kaksha ko hamesha hi dirghavritti hona p dega. upagrah vishuvath‌ rekha ke samaantar paridhi mean, athava usase samakon banata hua, ya kisi nirdharit kon mean chakkar kat sakata hai. yah nishchay hai ki 24 ghante mean apane aksh par ghoomati huee prithvi pashchim se poorv ki or jati hai aur usaki disha mean chho de hue prakshepastr ko is gati se labh mil sakata hai. dhruvoan ka chakkar katane par use yah labh nahian mil sakata.

kaksha ya paridhi ka chayan usaki upadeyata aur chho danevale desh ke parikshanakshetr ke vistar (proving range) par nirbhar karega. amariki upagrah ko agar 34° ke kon par chho da gaya to isaka ek mukhy karan yah bhi tha ki kep manaivaral se kairibiyan samudr ki or jo parikshan kshetr atalaantik samudr mean hai vah usi disha mean hai. yadi pratham prayogoan mean kisi prakar ki truti bhi ho jati to pratham ya dvitiy star kisi ghani abadi ke kshetroan mean n girakar samudr mean hi girate. isake viparit vaandanabarg se chho de hue upagrah dhruvoan ka chakkar katane ke lie bheje ge.

roosi parikshan kshetr bhi aisa hi tha, isilie roosi upagrahoan ne bhi lagabhag 65° ka kon banaya. staroan ke girane ke lie saibiriya ka registan upayukt sthan tha. ek bat yah bhi janane yogy hai ki vishuvath‌ rekha ke samaantar paridhi prithvi ke un aanshoan se ki jati hai jahaan abadi bahut kam hai aur upagrah ko bahut kam log dekh sakate haian. adarsh kaksha to vah hai jo dhruvoan ka chakkar katati hai, kyoanki jab tak upagrah ek chakkar katata hai, prithvi apane aksh se kuchh age badh jati hai. atev upagrah ka doosara chakkar prithvi ke any bhagoan se hota hai aur din mean 12 chakkar laganevala upagrah in 12 chakkaroan mean prithvi ke sabhi bhagoan ke oopar chakkar kat leta hai aur sari prithvi usaka nirikshan kshetr ban jati hai. ab tak jitane bhi upagrah chho de ge haian, ve sab vishuvath‌ rekha ke sath ek kon banakar chho de ge haian aur jitana hi adhik yah kon hota hai utana hi adhik prithvi ke vibhinn aangoan se usaka nirikshan kiya ja sakata hai. 34° ka kon banata hua amariki upagrah vishuvath‌ rekha ke donean or 40° tak hi drishtigochar hua. isake viparit roosi upagrah kaphi adhik kshetr se dekhe ja sake.

prithvi ke aksh ke nat hone ke karan in upagrahoan ki kaksha prithvi ke oopar aisi rekha banati hai jo tokari ki bunavat ki tarah dikhaee p dati hai. apane pratyek doosare chakkar mean upagrah prithvi ke adhik pashchimi bhagoan ke oopar hokar jata hai, kyoanki upagrah ke ek chakkar katane tak prithvi apane aksh par kuchh aansh poorv ki or ghoom jati hai.

bahustariy raketoan ki u dan ka kram yah hota hai ki sarvapratham pahale star par eedhann jalane lagata hai aur sara r aauket oordhv disha ki or pahale to dhire-dhire, phir tvarit gati ke sath kuchh kshanoan mean drishti se ojhal ho jata hai. do ya tin minat mean hi sara eedhann samapt ho jata hai. itane tho de samay mean hi prakshepastr 30-40 mil oopar chadh jata hai aur vahian pratham star vichchhinn ho jata hai. tab tak r aauket ki gati 3,000-4,000 mil prati ghanta tak ho jati hai. vichchhinn r aauket prithvi par avataran kshetr (launching site) se lagabhag 100-150 mil door gir jata hai. pahale star mean kaun-sa eedhann jalaya jae, yah nishchit nahian hai. yah drav aksijan evan gaisolin bhi ho sakata hai.

r aauket ka doosara star, jisamean kisi prakar ka any rasayanik eedhann prayukt ho sakata hai, upagah ko dhire-dhire adhik jhuki huee disha ki or le jata hai. is prakar r aauket 140 mil ki doori tak pahuanch jata hai aur tab tak usaki gati bhi 10,000 mil prati ghanta ho jati hai. doosara star tab vichchhinn ho sakata hai ya tisare star ke sath hi us ooanchi yatra mean laga bhi rah sakata hai aur 300 mil pahuanch chukane par vichchhinn ho jata hai. tabhi chalata hai tisara star, jo upagrah ko apani paridhi mean pahuanchakar usaki gati ko 18,000 mil prati ghante ya usake karib bana deta hai.

pahale upagrah vividh yantroan se susajjit rahe haian. inhian ke dvara ve vayumandal evan aantariksh sanbandhi batoan ki soochana rediyoan ki bhasha mean barabar prithvi ko bhejate rahe haian, jisase aantariksh ke tap, vayu ki dab, chuanbakiy shakti aur usak kshetr, brahmand mean soory ki kiranoan ke vikiran, ulkaoan ki sankhya adi par prakash p data raha hai.

yadi aantim star pahuanchane tak ham r aauket ki gati ko 25,000 mil prati ghante se adhik karane mean samarth ho sake to hamara prakshepastr upagrah n banakar grah banane ki kshamata rakhata hai. prithvi ke akarshan se door hone par bhi yah saur mandal se door nahian ja sakata aur vah svat: soory ke akarshan ke bhitar ka ek grah ban jata hai. 2 janavari, sanh‌ 1949 ko bheje ge roosi prakshepastr lyoonik-1 ka vajan 196 pauand tha. vah soory ki parikrama karata hua 9 karo d 15 lakh mitar se 12 karo d 25 lakh mil ki doori tak aandakar kaksha mean bhraman karane laga aur soory ki poori parikrama mean use 15 mahine lage. isi prakar amarikavaloan ne bhi 3 march, sanh‌ 1959 ko 133 pauand vajan ka ek prakshepastr, painiyar-4 chho da. vah soory se 9.17 karo d mil se 10.61 karo d mil ki doori tak gaya.

isake bad lyoonik-2 chho da gaya, jo chandrama ke dharatal se ja takaraya. lyoonik-3 ne to aisi paridhi banaee ki usane chandrama ke chhipe hue bhag ka chitr khianchakar vishv ke vaijnanikoan ko chamatkrit kar diya.

shh 200px|center chitr 1. lyoonik 2 ka marg

1. lyoonik-2; 2. chandrama-avataranabhoomi; 3. chandrama ka sthan, jab raanket chho da gaya tatha 4. chandrama ki kaksha.

vigat varshoan mean r aauket ki u danoan ke paryapt unnati huee hai aur in grahoan aur upagrahoan dvara prapt jnan ne prithvi ya brahmand sanbandhi vishad janakari karaee hai.

yadi sputnik-1 ne vijnan ka chamatkar dikhaya to sputnik-2 ne vayumandal ki oopari paratoan par soory ka prabhav aur jivadhariyoan par in u danoan ka kya prabhav hoga, yah bhi dikhalaya. amariki eksplorar-1 ne prithvi ke oopar sarvapratham vikiranamekhala (radiation belt) se parichit karaya aur yah bhi dikha diya ki ulkanuoan (micrometeorites) ka upagrah ko adhik khatara nahian hai. sath hi yah bhi siddh kar diya ki upagrah ka tap niyantran mean rakha ja sakata hai.

baiangard-1 ne, jo taul mean keval 3.25 pauanu ka tha, sabase pahale saur koshikaoan (solar cells) ki mahatta dikhaee, jinake bal par vaigard ki ayu 200 varsh ki ho saki hai. eksaplorar-3 ke chuanbakiy phitoan mean aizanah aauvar ki avaj le li gee thi aur sare vishv ko unaka ne varsh ka sandesh bheja gaya tha.

sputnik-3 1.5 tan ka tha. isamean anek prakar ke yantr bheje ge. baiangard-2 dvara 20 din tak lagatar badaloan ke avaran sanbandhi hal bheje ge. lyunik-1 aur payoniyar-4 prithvi ke akarshan se bahar bhi nikal ge. inase yah bhi maloom hua ki hamare vayumandal ke kan chandrama tak bikhare maloom p date haian. sath hi chandrama ke charoan or, prithvi ki avastha ke viparit, kisi bhi prakar ki vikiranamekhala (radiation belt) sanbhavana nahian hai aur n hi vahaan chuanbakiy kshetr maloom p data hai. lyoonik-2 ne nirdeshan ka vah chamatkar dikhaya jisake bal par 2,39,000 mil ki doori par 1 minat 13 sekand ki deri bhi pahale se bata di gee. lyoonik-3 ne keval chandrama ke pichhale bhag ka chitr hi nahian khiancha varanh‌ apane yantroan dvara us chitr ko uchit samay par sabhi jagah bhej bhi diya. 41/2 tan ka ek roosi aantirikshayan apane 18vean chakkar ke bad phir prithvi par nirdisht sthan ke bahut hi sannikat utar liya gaya aur isase jivadhariyoan ki u dan ki bhoomika taiyar ki gee. is prakar ke prayatn barabar kie ja rahe haian aur dhire-dhire ham prakriti par vijay pa rahe haian (dr aantiraksh yatra).

shh 200px|left chitr 2. lyoonik-2 ka marg

1. lyunik ka kakshasamatal, chandrama ki parikrama ke pahale; 2. lyunik ka kakshasamatal, chandram ki parikrama ke bad; 3. chandrama ki sthiti, jab upagrah chho da gaya; 4. chandrama ki kaksha; 5. chandrama ka sthan, jab chitr liya gaya,

tatha 6. chandrama ka kaksha samatal.

upagrah bhi ab vibhinn prakar ke ho ge haian. unaki upadeyata ke adhar par hi unaka nam nirdharit kiya jata hai.

rrituvijnan sanbandhi upagrah (Meteorolo ical satellite) ki yojana ban chuki hai. ye upagrah prithvi ki satah se 500-600 mil ki doori par ghoomate haian aur prithvi ke oopar badaloan ki dhakan ka nirikshan kar usaki sari soochana prithvi ke par sthit rritu-vijnan-keandroan par bheji jati hai. isake bal par dirghakshetri jalavayu ka poorvanuman lagaya jata hai. tiro-1 (Tiros-1) namak ek aisa hi upagrah aprail 1, sanh‌ 1960, ko oopar chho da gaya. isake dvara badaloan ke avaran ka chitr khianchana sanbhav ho saka. isi prakar ke any upagrah bhi chho de ge (dr. aantariksh yatra).

paraspar vartalap sanbhav karanevale sanchar-upagrah (communication satellites) bhi bheje ja chuke haian. mukhyat: ye do prakar ke ho sakate haian aur pratidhvani prayojan (Project echo) ke aantargat upagrahoan ki upadeyata ki pariksha kareange ki kahaan tak rediyo prakshepan ka kary karane mean saphal ho sakeange aur kahaan tak rediyo dvara dooraparyavekshan aur teliphon varta unake dvara sanbhav hai. un tak bheje hue rediyo sanketoan ko paravartit karate hue, ye varshoan tak aantariksh mean bhraman kar sakate haian. inake lie kisi prakar ki vidyutshakti ki avashyakata nahian. doosare ve upagrah haian jo pun:-prachalan-prakar (relay type) hote haian. ye sandeshoan ko vidyuth‌ ki gati se prapt kar, unhean sangrihit rakhate aur yathasamay unako bhejate haian. is prakar ke sanchar upagrahoan ki vidyutshakti ki avashyakata mahati hai, jo unhean saur koshikaoan (solar cells) dvara prapt hoti rahati hai.

nauchalan upagrah (navigational satellites) bhi ban chuki hai. ye upagrah 22,300 mil ki doori par raheange. kyoanki ye prithvi ki parikrama utane hi samay mean kareange jitane mean prithvi apane aksh par poori ghoom jati hai, isalie ye ek hi sthan par sthir maloom p deange. vishuvath‌ rekha ke samaantar 120° ka kon banate hue aise tin upagrah vishvavyapi prasaran (broadcast) sanbhav kar sakeange.

shh 200px|center chitr 3. sthayi upagrah ki kaksh ka nirman

1. pratham u dan; 2. chaturth star gativriddhi; 3. sthayi kaksha, tatha 4. bina gativriddhi ki kaksha.

vedhashala upagrah (astronomical satellites) to manav jati ke samane ek naya yug kh da kar deange. vayumandal ke karan vedhashalaoan ki jo kathinaiyaan haian aur jinake karan ham yatharth jnan prapt karane mean asamarth haian, ve sab vayumandal ke oopar aisi vedhashala ke sthapit karane se door ho jaeangi aur manushy ki keval drishti hi anant brahmand mean kaphi door tak pravesh nahian pa sakegi, varanh‌ usake vishv sanbandhi jnan mean bhi vriddhi ho jaegi. idhar hal mean bharat ne bhi ek upagrah taiyar kiya hai jo shighr hi roos ke aantariksh mean prakshepit kiya jaega.

aise hi upagrah nikat bhavishy mean ek prakar ke aantariksh steshan ho sakate haian jahaan se apani sudoor yatra ke lie janevale aantarikshayanoan ko eedhann bhandar se paryapt eedhann mil sakega. 14,000 mil prati ghanta ki gati aur usake oopar eedhann se bhari huee tanki yadi kisi r aauket ko prapt ho gee to sone mean suangadh ho jaegi. d aau. vernar farn braun ne aise hi aantariksh steshan (dr. aantiraksh steshan) ki yojana prithvi se 1,075 mil ki doori par banaee hai. yah prithvi ki parikrama har do ghante mean poori karega aur vishuvath‌ rekha se 45° ka kon banaega. yah steshan aangoothi ke akar ka hoga aur apani dhuri par paribhraman karane ke karan isake dvara ek kritrim akarshan bhi utpann hoga, jisase usake bhitar basanevaloan ko gurutvakarshan ki hinata ke karan kisi bhi prakar ki kathinaee nahian maloom p degi. is aantiraksh steshan ki rachana akash mean hi ki jaegi. sara steshan plastik ka bana hoga. ise samanavahak ashuyan (rocket express) sankuchit avastha mean vahaan le jaega aur vahaan vah phir phula liya jaega. pratyek samanavahak ashuyan 20 tan ka bojh is akashayan ki kaksha tak pahuancha dega. jab sara saman vahaan pahuanch jaega aur apani kaksha mean upagrah ki tarah paribhraman karata hoga tab ianjiniyar log use ekatrit kar aantarikshayan ki rachana kareange. isake bad phir chandralok ya any logoan ki yatra praanrabh hogi.

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