RU2614446C2 - Spacecraft control method for flying around moon - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: method comprises undocking of the spacecraft (SC) from the low-Earth orbital space station (OSS) and transferring to flight path to the moon with returning back. SC drifts down until the height of the OSS orbit upon returning to Earth by several brakings in its atmosphere. Node line of SC orbit is turned for plane alignment of the OSS and SC orbits after the first passage of the atmosphere at the point of intersection of these planes. In order to accomplish that, corresponding impulse is applied to the spacecraft perpendicular to the plane of the arrival orbit. Then the SC is docked again with OSS. The method will allow to fly around the moon and return to the initial low-Earth orbit in 6.5 days with reference speed input of about 1.7 km/sec.

EFFECT: final adjustment of spacecraft designed for multiple flights between low-Earth orbit and lunar OSS.

5 dwg

Description

The proposed control method can be used in space technology when organizing the moon around a spacecraft (SC), located, for example, as part of a near-Earth orbital station (OS). It is assumed that, after the Moon’s flight, the spacecraft returns to its initial near-Earth orbit for subsequent docking with the OS [1. "Moon. Step to the Solar System Development Technologies ”under. ed. V.P. Legostaeva, M, RSC Energia, 2011].

A known control method selected as an analogue in which the moon is circled. The spacecraft (SC) Apollo-12, launched into the reference orbit using the Saturn-5 launch vehicle (LV), was considered as a spacecraft. After the launch, the spacecraft performs a take-off impulse for the flight to the moon. Then, the impulse is performed at the Moon to transfer to the selenocentric orbit, and after the flight around the Moon, the spacecraft performs a take-off impulse for flight to Earth with subsequent entry into the atmosphere and landing in a given area and, therefore, the use of this spacecraft is many times impossible.

There is a known method of controlling the spacecraft for the moon around, selected as a prototype, including the application to the spacecraft located in the initial near-earth orbit of the pulse for the moon around the return path for the time t ₁ [2]. As the spacecraft, the Zond-7 spacecraft was used, which was launched into the reference orbit using the Proton launch vehicle. After launching into near-Earth orbit, the Zond-7 spacecraft performs a take-off impulse for flying around the Moon along a return trajectory [2. IN AND. Levantovsky "The mechanics of space flight in an elementary exposition", M, Nauka, 1980]. The main disadvantage of this control method is that the spacecraft after the moon’s flight enters the Earth’s atmosphere with subsequent landing in a given area, which, like the analogue, excludes its repeated use and is the main disadvantage.

The objective of the invention is the possibility of working out a spacecraft intended for multiple flights between the near-Earth OS and the OS located in the orbit of the Moon.

The technical result is achieved due to the fact that in the spacecraft control method during the moon’s flight, including the application to the spacecraft located in the initial near-earth orbit of the impulse for the moon’s flight along the return path in time t ₁ , in contrast to the known method, in time t ₂ after the moon’s flyby, necessary to coordinate the height of the orbit of arrival with the height of the initial near-earth orbit, the spacecraft is returned to the original plane of the near-earth orbit, for which, after the flight, the spacecraft is put into an elliptical orbit of arrival around the Earth, and then on the line of intersection of the planes of the orbit of arrival and the initial near-earth orbit, a pulse is applied to the spacecraft in the direction perpendicular to the plane of the orbit of arrival to rotate the line of nodes at an angle Δϕ determined by the formula:

Δϕ = ω _OZ ⋅ (t ₁ + t ₂ ),

where ω _ОЗ is the angular velocity of the precession of the plane of the initial near-Earth orbit.

We will consider the proposed method by the example of a spacecraft docked to the OS located in the initial near-Earth orbit. The technical result in the proposed control method is achieved due to the fact that after separation from the OS and the application of the take-off impulse, the spacecraft is transferred to the return path with the moon [2] with a duration t ₁ from the issuance of the take-off impulse to the return to Earth. Upon reaching the Earth, due to several decelerations in the Earth’s atmosphere, it switches to the so-called brake ellipses [2], gradually reducing the orbit height up to the OS orbit height in time t ₂ . During this total time t ₁ + t _{2 the} plane of the initial near-Earth orbit on which the OS is located will rotate relative to the initial position:

Δϕ = ω _OZ ⋅ (t ₁ + t ₂ ),

where ω _ОЗ is the angular velocity of the precession of the orbital plane, arising due to the off-center nature of the Earth's gravitational field and amounting to about 5 ° per day. To coordinate the planes of the arrival orbits and the initial near-Earth orbit, it is necessary to apply a pulse to the spacecraft in the direction perpendicular to the plane of the orbit of arrival to rotate the line of nodes by an angle Δϕ. Optimally, from the point of view of minimizing fuel consumption, this pulse should be performed after the spacecraft’s first entry into the atmosphere at the point closest to the apogee of the orbit. After coordination of the planes and a decrease in the orbit of the spacecraft to the height of the orbit of the spacecraft, the spacecraft is again docked to the OS.

The invention is illustrated in FIG. 1-4, where:

in FIG. 1 shows the flight diagram of the analogue - the flight to the lunar orbit of the spacecraft "Apollo-12",

in FIG. 2 shows the flight diagram of the prototype - flyby of the moon SC "Zond-7",

in FIG. 3 illustrates the flight scheme of the spacecraft according to the proposed method,

in FIG. 4 illustrates the rotation of the plane of the orbit of the spacecraft according to the proposed method

in FIG. Figure 5 shows a diagram with successive passes at a given distance from the Earth and subsequent exit into orbit of the OS.

In FIG. 1-5, the following positions are marked: 1 - the initial near-Earth orbit, 2 - the departure impulse to the Moon, 3 - the braking impulse, 4 - the selenocentric orbit, 5 - the departure impulse for the flight to the Earth, 6 - the trajectory of the flight to the Earth, 7 - the direction of movement Of the Moon, 8 — the spacecraft return trajectory after the Moon’s flight, 9 — angle of rotation of the Δϕ plane, 10 — current plane of the orbit of the OS, 11 — line of intersection of two planes, 12 — momentum of rotation of the plane of the orbit, 13 — atmosphere of the Earth, 14 — momentum of the transition of the spacecraft to near-Earth orbit.

In FIG. Figure 1 shows an analogue flight diagram - a flight to a lunar orbit according to the Apollo-12 spacecraft diagram in a reference frame rotating together with the Earth-Moon line. After the launch, the spacecraft is in the initial near-earth orbit (1). After the application of the take-off impulse (2), the spacecraft flies to the vicinity of the Moon, where, after the issuance of the inhibitory impulse (3), it passes into the selenocentric orbit (4). After ~ 4 days, when conditions appear for an optimal flight to Earth [3. "Fundamentals of the theory of spacecraft flight", ed. G.S. Narimanova, Mechanical Engineering, Moscow, 1972], the spacecraft performs a take-off impulse (5) and returns to Earth along the arrival path (6) with subsequent landing in a given area.

In FIG. Figure 2 shows the trajectory of the lunar flyby using the Zond-7 spacecraft also in the reference system rotating together with the Earth-Moon line. After the launch, the spacecraft is in the initial near-earth orbit (1). At a given point in the orbit, a take-off impulse (2) is applied to the SC, after which the SC flies around the Moon from the direction of its movement around the Earth (7) and flies back to the Earth (8) along the return trajectory, followed by landing in a given area.

In FIG. 3 in a projection on the plane of the equator of the Earth presents a flight diagram of the spacecraft according to the proposed method. After the application of the take-off impulse, the SC flies around the Moon from the side of its movement around the Earth (7) and along the return path (8) flies to the Earth with the transition to the initial near-Earth orbit (1), after which an impulse of rotation of the plane of this orbit to angle Δϕ (9), after which the spacecraft orbit plane will coincide with the current OS orbit plane (10).

In FIG. 4 illustrates the scheme of rotation of the plane of the orbit of the spacecraft at a given angle by the proposed method. After arriving to Earth, the spacecraft returns to the plane of near-Earth orbit (1), from which the departure began. In this case, in the time required for departure, the orbital plane of the OS (10) will unfold at an angle Δϕ (9). When passing the line of intersection of two planes (11), an impulse (12) is applied to the spacecraft in the direction perpendicular to the orbit plane (1) to rotate it to the OS orbit plane (10).

In FIG. Figure 5 shows the spacecraft’s transition from the return trajectory (4) due to successive passes in the Earth’s atmosphere (13) to the initial orbit of the near-Earth OS (1). The spacecraft enters the Earth’s atmosphere with the 2nd cosmic velocity. After the first deceleration of the spacecraft in the atmosphere, it passes into an elliptical orbit. Successive atmospheric passes are carried out until the next apogee of the orbit reaches the orbit height of the orbital station N _OS . Then, at the apogee of the orbit, an impulse (14) is performed for the final transfer of the spacecraft to the orbit of the near-Earth OS with subsequent docking with it.

Consider an example. Let V _{1 be the take} -off impulse to the Moon (~ 3200 m / s). The duration of the lunar flyby with subsequent return to Earth t ₁ is 5 days, and the spacecraft staying on transition brake ellipses for matching the arrival orbit altitude and OS orbit height t ₂ is 1.5 days. We determine the formula for the required angle of rotation of the plane of the orbit of arrival of the spacecraft:

Δϕ = ω _OZ ⋅ (t ₁ + t ₂ ) ° ~ 32.5 °

The height of the apogee of the first brake ellipse will be about 55 thousand km, and the height of the orbit at the intersection of two planes is about 22 thousand km. The cost of the characteristic speed for turning the orbit plane at this altitude will be about 1650 m / s [3], and the total flight duration is about 6.5 days.

Claims (3)

A method of controlling a spacecraft during a moon flight, including applying to a spacecraft located in the initial near-earth orbit, an impulse for a moon flight along a return path in time t ₁ , characterized in that, after time t ₂ after a moon flight, it is necessary to coordinate the height of the orbit of arrival with the height of the initial near-Earth orbit, the spacecraft is returned to the original plane of the near-Earth orbit, for which, after a flight, the spacecraft is put into an elliptical orbit of arrival around the Earth, and then to the lin and the intersection of the planes of the orbit and the initial arrival to the Earth orbit spacecraft momentum is applied in a direction perpendicular to the arrival plane of the orbit line of nodes for rotation through an angle Δφ, defined by the formula: Δϕ = ω _OZ ⋅ (t ₁ + t ₂ ), where ω _ОЗ is the angular velocity of the precession of the plane of the initial near-Earth orbit.

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