計算

読み込む軌道要素データ，iss_orbit.tle

・解析条件

startTime = datetime(2022,12,08,00,00,0);

stopTime = startTime + hours(12);

sampleTime = 5;

この時、ISSとFENGYUN 1C DEB が最も接近するとき，その時刻，直線距離，相対速度を求めなさい.

startTime = datetime(2020,6,02,8,23,0);
% stopTime = startTime + days(1);
stopTime = startTime + hours(3);
sampleTime = 5;
sc = satelliteScenario(startTime,stopTime,sampleTime);
sat = satellite(sc,"./iss_orbit.tle");
%show(sat) % 自分で再生ボタンを押してスタートさせる
%地表にfootprintを描く
groundTrack(sat,"Lead Time",12*60*60);
disp("----- start -----");
startTime_1 = datetime(2022,12,08,00,00,0);
stopTime_1  = startTime+ hours(12);
time_step_1 = seconds(5);
time_x_array   = [];
distance_array = [];
velocity_array = [];
for time_x = startTime_1 : time_step_1 : stopTime_1
    % disp(time_x);
    [pos_1, vel_1] = states(sat(1),time_x,"CoordinateFrame","inertial");
    [pos_2, vel_2] = states(sat(2),time_x,"CoordinateFrame","inertial");
    distance_21 = sqrt( ...
        (pos_2(1)-pos_1(1))^2 + ...
        (pos_2(2)-pos_1(2))^2 + ...
        (pos_2(3)-pos_1(3))^2 ...
        );
    
    rel_vel_21 = sqrt( ...
        (vel_2(1)-vel_1(1))^2 + ...
        (vel_2(2)-vel_1(2))^2 + ...
        (vel_2(3)-vel_1(3))^2 ...
        );
    time_x_array   = [time_x_array; time_x];
    distance_array = [distance_array distance_21];
    velocity_array = [velocity_array rel_vel_21];
end
% disp(size(distance_array));
[M,I] = min(distance_array);
% disp(M);
% disp(I);
disp("----- end -----");
% apple silicon m1, calc time = 3min
% disp(time_x_array(I));
% disp(distance_array(I));
% disp(velocity_array(I));
plot(time_x_array, distance_array);
X = sprintf('Time = %s, Distance(km) = %f, Relative V(km/sec) = %f \n', ...
    datetime(time_x_array(I)), distance_array(I)/1000.0, velocity_array(I)/1000.0);
disp(X);
play(sc); % 自動で再生ボタンが押されてスタートする

これを利用して、軌道解説お願いします。

[Atsushi Ueno]

• 公開されているTLEデータから適当に2つの衛星を選択しました
• (お手持ちのデータや時間範囲に変更すれば同様に適用可能だと思います)
• for文は不要で、vecnorm関数で相対距離と相対速度を演算しました

urlwrite("https://celestrak.org/NORAD/elements/stations.txt","iss_orbit.tle");
startTime = datetime(2023,3,5,22,49,45);
stopTime = startTime + minutes(3);
sampleTime = 5;
sc = satelliteScenario(startTime,stopTime,sampleTime);
sat = satellite(sc,"./iss_orbit.tle");
[pos_1, vel_1] = states(sat( 1),"CoordinateFrame","inertial");
[pos_2, vel_2] = states(sat(10),"CoordinateFrame","inertial");
distance_array = vecnorm(pos_1-pos_2, 3, 1);
velocity_array = vecnorm(vel_1-vel_2, 3, 1);
time_x_array   = startTime : seconds(sampleTime) : stopTime;
[M,I] = min(distance_array);
fprintf('Time = %s, Distance(km) = %f, Relative V(km/sec) = %f \n', ...
    datetime(time_x_array(I)), distance_array(I)/1000.0, velocity_array(I)/1000.0);

Time = 05-Mar-2023 22:50:55, Distance(km) = 6308.785048, Relative V(km/sec) = 6.884026 

plot(time_x_array, distance_array);

[Atsushi Ueno]

軌道解説とは具体的に何を意味していますか？ 少し Home work question の疑いが有ります。