Kuyika orbital: kulandira

Pa 10 March 2006, pambuyo pa miyezi isanu ndi umodzi m’nyanja ya Mars, Mars Reconnaissance Orbiter ya NASA idatulutsa ma injini ake asanu azikulu kwa mphindi 27. Panthawiyo, galimotoyo inali kumbuyo kwa Mars ndipo siinathe kulumikizana ndi ma radio: palibe amene padziko lapansi angadziwe ngati galimotoyo inagwira ntchito. Ngati mpweya wotentha udali wokwanira, ndegeyo ingakhale yapita ku Mars ndipo ipite m’mphepete mwa dzuwa.

Kufika sichoncho. Muyenera kuphedwa.

Onani

M’madera ena, “planet” sikuti ndi chinthu chokhacho chomwe chili pa dziko lapansi. Zimagwa kumbali yake, Kufulumizitsa monga imafika kumapeto, pa otsegulira curve anatchedwa hyperbola. Pamenepo, mpweya wozungulira umakhala wotentha kwambiri ndipo umayenda mofulumira kwambiri kuposa momwe zimakhalira panthawi yozizira.

Kuti ikhale, imafunika kulephera panthawi yoyenera, yomwe ili pafupi:

1. Capture burn. Magalimoto amawononga motsutsana ndi lingaliro la kuyendetsa. M’madera ena, mfundo ya kuwala imatha kukhala yosiyana ndi mfundo ya kuwala ya ..
2. Aerobraking. Pamene mpweya wamadzi umagwa, madzi amadzi amalowetsa kutentha kwa mpweya wozungulira m’malo mwa kutentha kwa mpweya. Pamenepo, mpweya wotentha kwambiri umatulutsa madzi otentha kwambiri ndipo mpweya wouma umatulutsa mpweya wambiri.
3. Kuyenda kwa sayansi. Pambuyo pa maulendo ambirimbiri m’miyezi isanu ndi umodzi, MRO inafika ku orbit yotsika kwambiri ya 250 mpaka 316 km ndipo ikhoza kujambula mapu a Mars.

Kumvetsa

Kuchokera kudziko lapansi panjira ya Hohmann, ndege yonyamula magalimoto imafika ku Mars za 2.65 km/s mofulumira kuposa Mars. Kuchokera pa mfundo ya Mars, yomwe ndi “mtunda wake wopanda malire”, v∞. Kugwa kwa 426 km pamwamba pa nthaka, imathamanga mpaka

v = √(v∞² + 2μ/r) = √(2.65² + 2 × 42,828 / 3,822) ≈ 5.4 km/s

Pa ellipse kuchokera 426 km mpaka 44,500 km, kuthamanga pa malo otsika ayenera kukhala 4.56 km / s (vis-viva). The yabwino, instantaneous kulowa burn ndi chifukwa chake za 0.87 km/s. A weniweni 27-mphindi kuwononga ndi yochepa kwambiri chifukwa chake ndi yofalikira pa curve; MRO’s slowed the spacecraft by about 1 km/s.

Kujambula mosalekeza m’mphepete mwa nyanja yozungulira idzawononga pafupifupi 2 km / s (onani Try it). Aerobraking amapulumutsa ambiri a zimene kusiyana, ndi mafuta opulumutsidwa amakhala spacecraft ndi sayansi.

Woyang’anira

A hyperbola has semi-major axis a = −μ/v∞² and eccentricity e = 1 + r_p v∞²/μ. Nthawi yoyenda kuchokera kumbali yakutali kupita ku periapsis imasankhidwa ndi hyperbolic Kepler equation M = e sinh F − F.

Kutenga Δv pa periapsis r_p m’lifupi ndi apoapsis r_a ndi

Δv = √(v∞² + 2μ/r_p) − √(2μ r_a / (r_p (r_p + r_a)))

yomwe ndi yaying’ono kwambiri kwa ellipse yotalika kwambiri (r_a → yayikulu): ndegeyo imatha kuwonedwa. Izi ndi chifukwa chake maulendo oyamba amalowa m’orbit yosagwira, ndipo chifukwa chake aerobraking kapena kuwononga pang’onopang’ono kumatsatira. Kutengerapo kwa Mars, aerocapture (kupita koyamba m’mphepete mwa mpweya pambuyo pa chinyezi) kungayambitse kuwononga kwa mpweya.