CN112906246B - Calculation method for assessment of intersection between space target and carrier rocket before launching - Google Patents

Calculation method for assessment of intersection between space target and carrier rocket before launching Download PDF

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CN112906246B
CN112906246B CN202110309840.6A CN202110309840A CN112906246B CN 112906246 B CN112906246 B CN 112906246B CN 202110309840 A CN202110309840 A CN 202110309840A CN 112906246 B CN112906246 B CN 112906246B
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赵治
崔文
张炜
罗朗
马鑫
陈治科
卢欣
王梁
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Abstract

The invention discloses a calculation method for evaluating the intersection of a space target before launch of a carrier rocket, which is a calculation method for screening out a safe launch window time meeting the conditions in a given launch window time period, wherein the screening conditions are as follows: the invention provides a calculation method for carrying out intersection evaluation on a theoretical flight path of a carrier rocket and a space target before launching aiming at the characteristic of the theoretical flight path of the carrier rocket and the on-orbit running rule of the space target, wherein the intersection distance between the carrier rocket and all space targets is smaller than a given safety threshold value.

Description

Calculation method for assessment of intersection between space target and carrier rocket before launching
Technical Field
The invention relates to the field of space measurement and control, in particular to a calculation method for assessment of intersection of a space target and a carrier rocket before launching.
Background
With the accelerated development of human aerospace industry and the increasingly severe aerospace activities, the number of in-orbit space targets (spacecraft, rocket bodies, space debris and the like) is continuously increased, and the space debris environment tends to be further deteriorated. By 12 months in 2020, the total number of trackable on-orbit SPACE targets published by the SPACE-TRACK website belonging to the American Federation SPACE war center is close to 21000. Statistically, more than 10 ten thousand space targets with a diameter larger than 1cm are in orbit, and the number of the tiny fragments with a diameter smaller than 1cm is millions. The dramatic increase in the number of space targets significantly increases the risk of collisions between targets entering the space and targets already in orbit, constituting a serious, persistent and widespread threat to the normal operation of spacecraft, launch of launch vehicles and sustainable development of near-earth space. Many instances of collisions between space targets have occurred in the aerospace history. For example, the gravitational gradient pole of a france Cerise satellite is broken by fragments of an araine rocket in the european space of 24 days 7 and 24 months 1996; the united states iridium satellite 33 and russian universe 2251 satellite collide at 2/11/2009, etc. The calculation shows that the collision speed between the space targets can reach 10 kilometers per second generally, the kinetic energy generated by the collision of the space targets with the weight of 10 grams and the spacecraft is equivalent to the kinetic energy generated by the collision of a car at the speed of 100 kilometers per hour, and therefore, the damage caused by the collision of the space targets with the size of centimeter or more is huge and unbearable.
The space target is in-orbit collided, and the influence and damage to the space environment are long-term. In order to maintain long-term sustainable development and utilization of space environment, the aerospace major countries in the world have developed actions in space target collision assessment and prediction. Meanwhile, in order to avoid the risk of collision during the launching process, the united nations and the peaceful use of the outer space committee propose in the "outer space activity long-term sustainability criteria": the pre-launch intersection assessment of the space object to be launched should be performed to avoid the risk of possible collisions with space targets during launch.
The intersection evaluation analysis work of the space target before launch of the carrier rocket is to calculate the condition that the intersection distance between the space target and the target in the orbit space is smaller than a given safety threshold value by utilizing the theoretical flight path before launch of the carrier rocket in a given carrier rocket launch window. At present, most scholars conduct analytical research on the collision risk between an on-orbit spacecraft and a space target, and conduct less research on the assessment of intersection before launch of a carrier rocket. The difference between the two is that as the launching window of the carrier rocket is generally more than half an hour, the corresponding flight trajectories are more than 1800 according to the time interval of 1 second, and the rendezvous assessment work before launching the carrier rocket needs to calculate the rendezvous situation between at least 1800 flight trajectories and all space targets; the flight path of the on-orbit spacecraft is relatively fixed, so the calculation amount of the collision risk assessment is much smaller than that of the on-orbit spacecraft, but the calculation accuracy requirements of the on-orbit spacecraft and the collision risk assessment are the same. In addition, the encounter assessment work before transmission typically requires completion within 1 hour. If the traditional spacecraft collision assessment method is still adopted to carry out the intersection assessment before launch of the carrier rocket, the requirements of high time efficiency and high precision are difficult to meet.
In view of the above reasons, the invention provides a calculation method for the intersection evaluation of the space target and the carrier rocket before launching aiming at the theoretical flight path characteristics of the carrier rocket and the on-orbit running rule of the space target, and can effectively solve the requirements of the intersection evaluation of the space target and the carrier rocket before launching on high timeliness and high precision.
Disclosure of Invention
The invention aims to solve the problems and provide a calculation method for the assessment of the intersection of the space target and the launch vehicle before launching.
The invention realizes the purpose through the following technical scheme:
the invention comprises the following steps:
s1: in a given launching window period, calculating the space position of the carrier rocket in an inertial coordinate system in the time period;
s2: converting the space position of the launch vehicle under a WGS84 coordinate system into the space position under a J2000 inertial coordinate;
s3: selecting a space target position corresponding to the position moment of the carrier rocket according to the position of the space target J2000 inertial coordinate in the step S1;
s4: calculating a relative distance between the two targets based on the position of the launch vehicle calculated in step S2 and the position of the target in the screening space in step S3;
s5: calculating the collision risk of the space target and the carrier rocket by adopting a Lagrange interpolation algorithm according to the relative distance sequence in the step S4;
s6: calculating dangerous launching time of the space target and the carrier rocket according to the method of the steps S2-S5;
s7: and evaluating the time meeting condition according to the method of the steps S2-S6, and counting to obtain the safe emission time period and the dangerous emission time period in the emission window time period.
The invention has the beneficial effects that:
the invention relates to a calculation method for evaluating the intersection of a space target and a carrier rocket before launching, and compared with the prior art, the calculation method for evaluating the intersection of the space target and the carrier rocket theoretical flight path before launching is provided by the invention aiming at the characteristics of the carrier rocket theoretical flight path and the on-orbit running rule of the space target.
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FIG. 1 is a graph of the altitude of the launch vehicle of the present invention.
Detailed Description
The invention will be further described with reference to the accompanying drawings in which:
the technical scheme of the invention is as follows: in a given emission window time period, screening out a calculation method of a safe emission window time meeting conditions, wherein the screening conditions are as follows: the method is characterized in that the intersection distance between the carrier rocket and all space targets is less than a given safety threshold, and comprises the following steps:
the method comprises the following steps: at a given transmission window period t 0 ,t 1 ]In the space, the time length of flight of the carrier rocket is known as T seconds, and the space position of the carrier rocket at one second and one point in the WGS84 coordinate system is known as [ x [ ] 0i y 0i z 0i ]Wherein i is 1,2, … n, n is an integer part of T; knowing the TLE numbers of all m space objects, calculating the TLE numbers at [ t ] according to 1 second time interval based on SGP4/SDP4 model 0 ,t 1 +T]The spatial position in the J2000 inertial coordinate system in the time interval is recorded
Figure BDA0002989146300000041
Wherein j is 1,2, … M, k is 1,2, … M, M is (t) 1 -t 0 ) The time corresponding to each spatial position is recorded as the integer part of x 86400+ T
Figure BDA0002989146300000042
Step two: at t l =t 0 + Δ t, where Δ t 1 sec, L0, 1,2, … L, L is (t ═ L ═ 1 sec 1 -t 0 ) X 86400+1 integer part, space position of carrier rocket in WGS84 coordinate system x 0i y 0i z 0i ]Conversion to spatial position [ x ] in J2000 inertial coordinates 0li y 0li z 0li ]Wherein [ x ] oli y oli z oli ] T =R[x 0i y 0i z 0i ] T R is a transformation matrix from a WGS84 coordinate system to a J2000 inertial coordinate system;
step three: according to [ t ] in step one 0 ,t 1 +T]Position in inertial coordinates of spatial object J2000 over time
Figure BDA0002989146300000043
Selecting a space target position corresponding to the position moment of the carrier rocket, and recording the space target position as
Figure BDA0002989146300000044
Wherein s satisfies t j(s+1) =t l S is [0, M-1 ]]An integer in between;
step four: according to the carrier rocket position [ x ] calculated in step three 0li y 0li z 0li ]And step four, screening the spatial target position
Figure BDA0002989146300000045
The relative distance between the two objects can be calculated
Figure BDA0002989146300000046
Step five: relative distance d according to the four steps li The sequence adopts a Lagrange interpolation algorithm to obtain the transmitting windowMouth t l Minimum value d of relative distance between flight path of time carrier rocket and jth space target ljmin Setting a safe threshold value of the crossing distance between the carrier rocket and the space target as D safe When d is ljmin >D safe When d is less than d, it means that the jth space target has no collision risk with the carrier rocket ljmin ≤D safe When the space is empty, the j-th space target forms a collision risk to the flight of the carrier rocket;
step six: according to the method from the third step to the fifth step, calculating the minimum value d of the relative distances between all m space targets and the carrier rocket ljmin I.e., j ═ 1,2, … m; when all m minimum distances d ljmin All satisfy d ljmin >D safe Then, it represents the emission window t l The time is the safe transmitting time, otherwise, the time represents the transmitting window t l The moment is a dangerous transmitting moment;
step seven: evaluating all t according to the method from step two to step six l =t 0 A meeting at time + Δ t, where Δ t ═ L · 1 sec, L ═ 0,1,2, … L, and L is (t ═ L · 1 sec) 1 -t 0 ) The integer part of x 86400+1, then the time interval of the emission window t can be obtained by statistics 0 ,t 1 ]A safe emission period and a dangerous emission period.
Example (b):
setting a certain carrier rocket to be launched from a Becknul launching site in 26 days in 12 months in 2020, wherein the maximum flying height of the rocket is 660 kilometers, the flying time is 607 seconds, a launching window is from 12 hours to 12 hours in Beijing, 30 minutes, the safety threshold of the intersection distance between the carrier rocket and a SPACE target is preset to be 20 kilometers, SPACE target cataloging data select the number of TLE (total number of 20578) published by a SPACE-TRACK website belonging to 26 Riegand American Union SPACE war center in 12 months in 2020, and the flying height of the carrier rocket changes along with time as shown in figure 1;
by adopting the calculation method, the rendezvous evaluation is carried out on the carrier rocket and the space target before launching, and the rendezvous evaluation result is shown in table 1 in a time period from 12 months, 26 days, 12 days and 30 minutes in a launching window 2020:
TABLE 1 Conflict assessment Security Transmit Window period
Figure BDA0002989146300000051
Figure BDA0002989146300000061
TABLE 2 specific encounter between carrier rocket and space target
Figure BDA0002989146300000062
Figure BDA0002989146300000071
Figure BDA0002989146300000081
The selected computer is configured as follows: inter i5 CPU @3.7GHz,4.0G memory, Windows764 bit operating system. Under these conditions, the calculation results are shown in tables 1 and 2, and the time required for completing the calculation is 31 minutes and 48 seconds, which is far less than the time requirement of 1 hour. It can be seen from tables 1 and 2 that, by using the calculation method of the present invention, for a 30-minute-duration launch window, a 1-second window interval step is adopted to develop the rendezvous assessment analysis between the launch vehicle and more than 20000 space targets, and the safe launch window time period meeting the given conditions can be screened out only 31 minutes and 48 seconds, and meanwhile, the rendezvous distance calculation accuracy reaches the meter level. This shows that the calculation results obtained by the method can meet the requirements of high timeliness and high precision at the same time.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (8)

1. A calculation method for assessment of intersection of a space target before launch of a launch vehicle is characterized by comprising the following steps:
s1: in a given launching window period, calculating the space position of the carrier rocket in an inertial coordinate system in the time period;
s2: converting the space position of the launch vehicle under a WGS84 coordinate system into the space position under a J2000 inertial coordinate;
s3: selecting a space target position corresponding to the position moment of the carrier rocket according to the position of the space target J2000 inertial coordinate in the step S1;
s4: calculating a relative distance between the two targets based on the position of the launch vehicle calculated in step S2 and the position of the target in the screening space in step S3;
s5: calculating the collision risk of the space target and the carrier rocket by adopting a Lagrange interpolation algorithm according to the relative distance sequence in the step S4;
s6: calculating the dangerous launching time of the space target and the carrier rocket according to the method of the steps S2-S5;
s7: and evaluating the time meeting condition according to the method of the steps S2-S6, and counting to obtain the safe emission time period and the dangerous emission time period in the emission window time period.
2. The method of claim 1, wherein the method comprises the steps of: the step S1 is embodied as a step of transmitting in a given emission window period t 0 ,t 1 ]In the interior, the time length of flight of the carrier rocket is known as T seconds, and the spatial position of the carrier rocket at a point in one second under the WGS84 coordinate system is x 0i y 0i z 0i ]Wherein i is 1,2, … n, n is an integer part of T; TLE root knowing all m spatial targetsThe value is calculated at t at intervals of 1 second based on the SGP4/SDP4 model 0 ,t 1 +T]The spatial position in the J2000 inertial coordinate system in the time interval is recorded
Figure FDA0002989146290000011
Wherein j is 1,2, … M, k is 1,2, … M, M is (t) 1 -t 0 ) The time corresponding to each spatial position in the integer part of x 86400+ T is expressed as
Figure FDA0002989146290000012
3. The method of claim 1, wherein the method comprises the steps of: the step S2 is specifically executed at t l =t 0 + Δ t, where Δ t 1 sec, L0, 1,2, … L, L is (t ═ L ═ 1 sec 1 -t 0 ) X 86400+1 integer part, space position of carrier rocket in WGS84 coordinate system x 0i y 0i z 0i ]Conversion to spatial position [ x ] in J2000 inertial coordinates 0li y 0li z 0li ]Wherein [ x ] oli y oli z oli ] T =R[x 0i y 0i z 0i ] T And R is a transformation matrix from a WGS84 coordinate system to a J2000 inertial coordinate system.
4. The method of claim 1, wherein the method comprises the steps of: the step S3 is specifically performed according to [ t ] in the step S1 0 ,t 1 +T]Position in space target J2000 inertial coordinates over time
Figure FDA0002989146290000021
Selecting a space target position corresponding to the position moment of the carrier rocket, and recording the space target position as
Figure FDA0002989146290000022
Wherein s satisfies t j(s+1) =t l S is [0, M-1 ]]An integer in between.
5. The method of claim 1, wherein the method comprises the steps of: the step S4 is specifically to calculate the position [ x ] of the launch vehicle according to the step S2 0li y 0li z 0li ]And screening spatial target positions in step S3
Figure FDA0002989146290000023
The relative distance between the two objects can be calculated
Figure FDA0002989146290000024
6. The method of claim 1, wherein the method comprises the steps of: the step S5 is specifically executed according to the relative distance d in the step S4 li The sequence adopts Lagrange interpolation algorithm to obtain the emission window t l Minimum value d of relative distance between flight path of time carrier rocket and jth space target ljmin Setting a safe threshold value of the crossing distance between the carrier rocket and the space target as D safe When d is ljmin >D safe When d is less than d, it means that the jth space target has no collision risk with the carrier rocket ljmin ≤D safe And then, the j-th space target forms a collision risk to the flight of the carrier rocket.
7. The method of claim 1, wherein the method comprises the steps of: the step S6 is to calculate the minimum value d of the relative distances between all m space targets and the launch vehicle according to the method from the step S3 to the step S5 ljmin I.e., j ═ 1,2, … m; when all m minimum distances d ljmin All satisfy d ljmin >D safe Then, it represents the emission window t l The time of day being a safe transmission time of dayOtherwise, it represents the emission window t l The time instant is a dangerous transmission time instant.
8. The method of claim 1, wherein the method comprises the steps of: the step S7 is specifically to evaluate all t according to the method from the step S2 to the step S6 l =t 0 A meeting at time + Δ t, where Δ t ═ L · 1 sec, L ═ 0,1,2, … L, and L is (t ═ L · 1 sec) 1 -t 0 ) The integer part of x 86400+1, then the time interval of the emission window t can be obtained by statistics 0 ,t 1 ]A safe transmission period and a dangerous transmission period.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109573103A (en) * 2018-11-19 2019-04-05 北京航天自动控制研究所 A kind of remaining carrying capacity appraisal procedure declined under fault condition suitable for thrust
CN110044362A (en) * 2019-04-29 2019-07-23 中国人民解放军32035部队 The quick calculation method of relative distance minimum between a kind of extraterrestrial target
CN112179207A (en) * 2020-09-17 2021-01-05 湖北航天技术研究院总体设计所 Carrier rocket task planning method for spacecraft fast rendezvous

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109573103A (en) * 2018-11-19 2019-04-05 北京航天自动控制研究所 A kind of remaining carrying capacity appraisal procedure declined under fault condition suitable for thrust
CN110044362A (en) * 2019-04-29 2019-07-23 中国人民解放军32035部队 The quick calculation method of relative distance minimum between a kind of extraterrestrial target
CN112179207A (en) * 2020-09-17 2021-01-05 湖北航天技术研究院总体设计所 Carrier rocket task planning method for spacecraft fast rendezvous

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
深空机动对运载火箭发射火星探测轨道研究;耿光有等;《宇航学报》;20190530(第05期);全文 *
空中发射运载火箭弹道优化设计;李庆龙等;《宇航总体技术》;20200915(第05期);全文 *

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