Method for generation of control actions on spacecraft

FIELD: transport.

SUBSTANCE: invention relates to spacecraft (SC) motion control using solar radiation pressure forces distributed over SC working zones. The latter are formed as flat parallel optically transparent droplet flows. Distance between droplets of R radius in each flow in its lengthwise direction (S_x) and frontal-lateral direction (S_y) is divisible by $$\sqrt{2}R$$ . Number of flows is $$n=(S_x/\sqrt{2}R)-1$$ . By mutual bias of flows in direction of their motion for $$\sqrt{2}R$$ distance droplet mist flows are generated in number of $$m=(S_y/\sqrt{2}R)-1$$ . Each of the mentioned flows is biased relative to previous flow for $$\sqrt{2}R$$ distance in frontal-lateral direction. Thus opacity in frontal-lateral direction and transparency in direction of plane perpendicular to a flow is created. Unit distributed light pressure force is regulated by changing radius and number of droplets coming to point of it application in unit time. Total action value is regulated by changing number of droplet jets.

EFFECT: increase of efficiency of light pressure distributed external forces usage by means of decreasing their disturbing effect on relative SC motion.

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The invention relates to the field of space technology and can be used in motion control systems SPACECRAFT).

There is a method of generating control impacts on the SPACECRAFT by means of a power electrodynamic phenomena (C. P. Burdukov, Y. I. Danilov. Physical problems cosmic traction energy. M, Atomizdat, 1969, page 240). Traction force (F₁) Lorentz occurs by the interaction of CA with charge Q moving with velocity V_awith the external electrostatic and magnetic fields In and is determined by the formula

$$F_1=Q(E+[V_a,B])(1)$$

A device that implements the method can serve as an electric sail for the translational movement of the spacecraft (patent US 7641151 B2, 02.03.2006, B64G 1/22, 1/40). The device contains a number of electrically conductive elongated distributed elements radiating from the body due to its rotation. Generator mounted in the housing, charges elongated elements so that they all carry a positive charge.

The nature of the generation of control actions for change is the orbit altitude, after "turning on" of the charge depends on the orientation angles in the geomagnetic coordinate system, the relationship of the charge to the mass of the SPACECRAFT and flight duration. The application of control actions performed by on / off charge, while the value of a single distributed power form by charge an individual item, and the amount of the total impact by forming the front of the electric field generated radially distributed elongated charged elements.

The disadvantage of this method is the need to produce electricity costs, including ongoing additional charge elements, especially in low-earth orbits flight KA, where there is exposure to the atmosphere, leading to change in the shape of sails (supported by centrifugal forces), and to the discharge of its elements, interacting with the remnants of gases. In addition, the generated charge is necessary to protect the onboard equipment, as well as its interaction with onboard electrical devices can cause short circuits.

Known selected as a prototype method for generation of control actions on the spacecraft, based on the effects of distributed external forces of radiation pressure on the SPACECRAFT (C. A. Griliches, p. P. Orlov, L. B. Popov. Solar is the first energy and space flight. M., "Nauka", 1984, page 155). The total pressure of solar radiation (R_withper unit surface of the SPACECRAFT is determined by the formula

$$p_c={(L\text{ç/L)}}^{\text{2}}\lfloor (1-{\rho }_{\text{ç}})\cos \vartheta +2{\rho }_{\text{ç}}{\cos }^2\vartheta \rfloor E_c/C,(2)$$

where L_çL - distance from the Sun to the Earth and to KA; ρ_ç- mirror reflection coefficient; υ is the angle of incidence of the radiation on the working surface KA; E_c- the solar constant; C is the speed of light.

As workers can be used the surface of the solar sail, consisting of separate elements formed of flexible parallel plates or strips located in the same direction to the specified plane and distributed by individual groups. When this tape or strips of one group are oriented to the Sun at the same time, but separately from the tapes and strips of the other group, around mutually parallel axes and given direction to the Sun.

Thrust F_Pcreated flat solar sail area S set which is according to the formula

$$F_P=p_{c}S.(3)$$

To assess the effectiveness of using this method for generation of control actions on the SPACECRAFT performed a comparative evaluation of mass propulsion (actually sails) and the rest mass of the SPACECRAFT. The lower specific gravity of the propulsion device and more pressure solar radiation, the more effective application of the method of formation. In addition, the amount of the total exposure to regulate the increase in the size of the area of application of the external forces of radiation pressure, which leads to an increase in the size of the propulsion device and the inertial characteristics of SC as a whole. The distribution of the external force action is in the plane perpendicular to the direction of flux, with resultant located at a distance from the main Central axes of the SPACECRAFT. This leads not only to move the center of mass of the SPACECRAFT, but also the formation of additional control points, which you must fend off to maintain the required orientation of the exposed working surface of the Sun.

The present invention is directed to a uniform distribution of inertial-mass characteristics of SC with respect to the axes of the associated basis KA is ri the formation of a single control actions through effective use of distributed external light forces to control the motion of the SPACECRAFT, as well as improving SPACECRAFT control.

To achieve the technical result, in the formation method of control actions PA spacecraft, based on the effects of distributed external forces of radiation pressure on the spacecraft, distributed external forces shape by creating a zone of application of control actions of flat parallel optically transparent trickling streams, trickling streams which are exposed to solar radiation, while the distance between the drops of radius R in each flat flow along it (S_xand in its frontal-transverse direction (S_y) is a multiple of$$\sqrt{2}R$$and the number of these flat trickling streams n, where$$n=(S_x/\sqrt{2}R)-1$$, the offset of each subsequent flat trickling streams relative to previous in the direction of their movement at a distance of$$\sqrt{2}R$$form m threads drip cloths, where$$m=(S_y/\sqrt{2}R)-1$$each of which is offset from the previous one in the frontal-lateral direction at a distance of$$\sqrt{2}R$$creating a front optical opacity drip flow in the frontal-lateral direction and optical transparency in the direction of the plane perpendicular to the flow, while the value of a single distributed power adjust change of the radius R and the number of drops that come in the point of application per unit time, and the amount of the total exposure to govern the change in the number of streams of drops.

The technical result in the newly developed method of generation of control actions on the AC concluded in the formation of the control inputs from distributed external forces of radiation pressure due to solar light irradiation floating mass in the form of droplets from one part of the SPACECRAFT to another.

The proposed technical solution, the AC and the drop radius R, is moved with a certain speed (V) from one point to another, constitute a closed system, and accordingly drop to create additional control action cannot. If a drop during the flight be exposed to the solar radiation, then it will operate, see (3), external power

$$F_k=p_{c0}{S}_k,(4)$$

where p_c0=(Lç/L)²(1+ρ_ç)E_c/C - the value of the expression (2) when ϑ=0;

S_k=πR²- the area of the midship drops.

When the drops hit the point PA, the surface of the collection on the SPACECRAFT impacted the momentum of external forces

$$\Delta p_k=F_k\Delta t,(5)$$

where Δt - L/V - flight drops; L, V - distance flight and the speed drops accordingly.

The jet is made up of individual drops, will operate at the point of application on the surface of the collecting continuous period of time Δτ. It should also be noted that the product of the interval time-of-flight drops on the power of the F_kacting perpendicular to the direction of flow of drops, eight to ten orders of magnitude smaller than the product of mass drops its speed (shown below). Therefore, when the migration BLOB and, therefore, the stream generally do not deviate from their original direction of motion. Thus, the jet assessement formation control on the SPACECRAFT. From jets are formed of flat optically transparent drip threads that are exposed to solar radiation.

For solving the problem of formation control actions on the AC front is formed optically opaque surface drip flow. Diagram of the formation shown in Fig.1 and Fig.2. In addition to the previously introduced additional discussion: S_x, S_y, S_z- the distance between the drops along the flow in the frontal-lateral direction and in the direction of the plane perpendicular to the flow, respectively; OXYZ - designation build axes drip cloths; P_1,2streams of drop cloths.

Drip cover flow is formed from the condition of the existing constraints of the area with its integration into the overall design of the KA and the minimum required mass of a particular substance drops. I.e., given the size of the shroud should ensure that it is front-opacity minimum number of drops. As can be seen from Fig.1, 2, this condition satisfies the case when the distance between the centers of adjacent projections of Medela drops on the frontal plane XOY is$$\sqrt{2}R$$and the distance between the drops along the stream and in its frontal-transverse direction (OY axis) is a multiple of$$mrow>\sqrt{2}R$$.

To ensure the front optical opacity flow in the direction of flat optically transparent drip streams are shifted relative to previous planes at a distance of$$\sqrt{2}R$$along the axis OX. While the number of planes n, providing opacity is$$n=(S_x/\sqrt{2}R)-1$$. Thus, a first flow drip cloths P₁(see Fig.2).

Another stream of drop cloths P₂is offset from the axis of the shelter at a distance of$$\sqrt{2}R$$(Fig.2). And the m-th number of threads drip cloths, where$$m=(S_y/\sqrt{2}R)-1$$provides optical opacity in the anterior-lateral direction.

General view of the drip shroud shown in Fig.3, which also presents a fragment of the plane on which the generated distributed control what their impact, sent to SC from drip jets. In addition to the previously introduced in Fig.3 presents denote the i-x jets (i=1, 2, 3...) forces and their effects (F_ksi. The largest single force at fixed reflective properties drops (ρ_ç=const) is directly proportional to its radius R, see (3), where S=πR². In addition, the magnitude of the impact of the jet depends on the number of drops (n_kin the point of its application, which is determined from the equation of motion of the jet

$$n_k{S}_x=V_x\Delta t,(6)$$

where V_x- the speed of the jet, m/S.

It is evident from Fig.3 shows that the total impact on the SPACECRAFT depends on the number of jets, which, in turn, depends on the size of the shroud in the frontal-lateral direction.

The location of the surface of the collection drops on the SPACECRAFT determines the application of control actions. These effects can be used to control the movement of the center of mass of the SPACECRAFT, and around its center of mass by moving the surface of the collection drops in a given area.

As an example, we can consider drip veil of liquid tin (ρ=6600 kg/m³) [5], moving with velocity V_x=5 m/s, while SEL is Ana parameters: R=1 mm; S_x=S_y=11,3 mm; S_z=10 mm Distance between the drops of the axes OX and OY is a multiple of$$\sqrt{2}R$$the odds ratio of n_x=n_y=8.

The amount of motion drops Q_k

$$Q_k=4/3\pi R^3\rho V_x\approx \mathrm{1,38}\times {10}^{-4}(H\cdot c).(7)$$

Mirror reflection coefficient of liquid tin at a temperature T₀=1000K. equal to ρ_ç≈0,7. Then the pressure of solar radiation at E_c=1360 W/m²ua geocentric orbit will be R_C0≈7,7·10^-6PA, and the force acting on the drop, see (4), F_k=2,418×10^-11H. When the distance from the generator drops to the collection device L_x=1,13 m (Fig.3), the pulse power light effects on drop

$$Q_c=F_k(L_x/V_x)\approx \mathrm{5,4}\cdot {10}^{-12}(H\cdot c).(8)$$

Thus, Q_k>>Q_cand deviation drops from the direction originally given movement under the force of light pressure will not occur. The number of drops in the alignment (between the generator and the acquisition device, L=L_x) jet

N_kx=L_x/S_x=100.

For further approximate calculation shroud set the size of the front (along the axis OY) L_y=1,13 m Then the number of jets in the same plane

N_sy=L_y/S_y=100.

The depth of the shroud

L_z=S_z·n_x·n_y-1=0,63 (m).

The pulse strength of the i-th droplet stream, where i=1, 2, 3,..., to the point its applications

ΔWⁱ=n_kiΔp_k.

The number of drops in the jet is determined from the equation of motion (6)

$$n_{ki}=(V_x\Delta t)/S_x.(9)$$

The value of Δp_kis determined from the expression (5). Then if V=V_x=const, L=L_xusing (5) and (9)? get

$$\Delta W^i=F_{ki}(L_x/S_x)\Delta t.(10)$$

From (10) it follows that the impulse force drip jet is governed by the radius of the droplet, see (4), and the number of drops that come in the point of application of the jet per unit time (Δτ=1C). The more drip stream closes on the target area of the shroud, the greater the force impulse drip stream.

The results of the calculation of the droplet stream (see Fig.3) are presented in table 1. Thus the values of F_kjcalculated taking into account the space S_kj, j=1, 2, ..., 6 for the respective illuminated forms of Medela drops. The total momentum of the force generated from the number of jets$$N_{Si}^j$$with different shape of the midsection drops

$$\Delta W_{\Sigma }^j=N_{Si}^j\Delta W_i^j,(H\cdot c).(11)$$

The total momentum of the force from the flow drops

As an example of the device for forming drip cloths can be considered a liquid droplet radiator (patent US 4572285, 10.12.1984; Liquid-refrigerator drip emitter system heat for efficient energy conversion in space. Astronautics and acetogenic, No. 2, 1983), containing the generator drops, drip guide the flow into the reservoir placed at a certain distance from the generator and receiving the drip stream. When this dies single drip cloths in the generator should be placed in a special way, according to the scheme shown in Fig.3 (a view along arrow M), where the point of projection of the nozzles holes on the surface of the collection. Further, sequential shift m-th nozzles single drop cloths along the axis OY, in which each shroud offsets at a distance of$$\sqrt{2}R$$formed opacity flow in the frontal-lateral direction.

For comparative validation of the proposed method for generation of control actions on the SPACECRAFT with the method of forming the impact of solar on the effect on a flat surface KA, the frontal area of the shroud (S_P) is equal to the surface area of the SPACECRAFT in the form of solar sails S_PR, i.e., S_P=S_PR=L_x·L_y=1,28 (m²). The impulse force of radiation pressure on the surface of the sails of the specified area will be equal when R_C0≈7,7·10^-6PA, Δτ=1C

$$\Delta P_{PR}=p_{c0}\cdot S_{PR}\cdot \Delta t=\mathrm{9,86}\cdot {10}^{-6}(H\cdot c).(13)$$

Thus, the accuracy of the adopted computational approximations of the values of ΔP_PRand ΔW are the same (see table.1).

Will make the assessment of the mass of the working fluid (e.g., xenon)that can be saved when using the proposed method for generation of control actions. However, we must consider the motion control of SPACECRAFT using electric propulsion stationary plasma thrusters (SPT), with the maximum specific impulse among the used jet engines. For this we define the value of the characteristic velocity ΔV_xthat can provide a device fo the formation of the impacts set the SPACECRAFT total mass M=2×10³kg, for example, within 300 days of operation (number of seconds N_c=25,92×10⁶) when the total impulse of the force on the shroud drops AW (see tab.1):

$$\Delta V_x=\frac{\Delta W{N}_c}{M}\approx \mathrm{0,13}(m/\mathrm{with\; a})$$.

Next, you should determine the cost of fuel, such as SPD-70, ΔQ with a thrust P=4×10^-2N. and second mass flow$$\stackrel{}{m}=\mathrm{2,7}\times {10}^{-6}Kg/\mathrm{with\; a}$$to obtain ΔV_xKA stated mass

$$\Delta Q=\stackrel{}{m}\frac{M\Delta V_x}{P}\approx \mathrm{0,02}(Kg)$$.

It should be noted that in addition to the cost of fuel will also need the cost of electrical power to obtain the specified characteristic speed. If making a comprehensive use of the device formation with drip radiator, and on the additional mass of the SPACECRAFT in the formation of the proposed control actions is not required.

From the point of view of dynamic traffic management KA, the proposed method for generation of control actions allows for more efficient management. It is primarily associated with the ability to change the design and management of the moments of inertia of the apparatus. The design of solar sails allows to distribute its mass relative to the same plane, perpendicular to the direction of movement of the apparatus. Equivalent to drip forming device control actions, implementing the proposed method allows to distribute its mass relative to several tens, or even hundreds of planes form a flat parallel optically transparent trickling streams. The number of planes are also perpendicular to the direction of movement of the apparatus will be determined by the parameters of the shroud S_x, S_y, S_z. Thus, it is possible to reduce the difference between the principal moments of inertia of the SPACECRAFT and thus reduce the effect of external gravitational torque, which is disturbing when stabilization of the angular motion of the device.

If through the plane of the drip collection shroud passes a longitudinal construction axis KA, coincident with the direction of its movement, and the impulses of the forces apportioned on either side of the axis, the control points when formirovaniya impacts would not be created. This simplifies the task of stabilizing the angular motion of the SPACECRAFT during orbit correction using the proposed method for generation of control actions.

LITERATURE

1. B. N. Burdakov, Y. I. Danilov. Physical problems cosmic traction energy. M, Atomizdat? 1969.

2. Electric sail for the translational movement of the spacecraft. Patent US 7641151 B2, 02.03.2006, B64G 1/22, 1/40.

3. C. A. Griliches, P. P. Orlov, L. B. Popov. Solar and space flight. M., "Nauka", 1984.

4. Spacecraft with a solar sail. Patent FR 2711111 A1, 12.10.1993, B64G 1/36, 1/44.

5. G. C. Konyukhov, A. A. Koroteev. Study of radiative cooling of the coolant space power plants in the drip refrigerators-emitters, " Izv. Russian Academy of Sciences. Energy. 2006. No. 4.

6. Liquid droplet radiator. Patent US 4572285, 10.12.1984.

7. Liquid-refrigerator drip emitter system heat for efficient energy conversion in space. Astronautics and acetogenic, No. 2, 1983.

The formation method of controlling impacts on the spacecraft, based on the effects of distributed external forces of radiation pressure on the spacecraft, wherein the distributed external forces shape by creating a zone of application of control near the action of flat parallel optically transparent trickling streams, drip jets which are exposed to solar radiation, the distance between the drops of radius R in each flat flow along it (S_xand in its frontal-transverse direction (S_y) foldand n specified flat trickling streams, where, the offset of each subsequent flat trickling streams relative to previous in the direction of their movement distanceform m threads drip cloths, where, each of which is offset from the previous one in the frontal-lateral direction at a distance ofcreating a front optical opacity drip flow in the frontal-lateral direction and optical transparency in the direction of the plane perpendicular to the flow, while the value of a single distributed power adjust change of the radius R and the number of drops that come in the point of application per unit time, and the amount of the total exposure to govern the change in the number of streams of drops.