#!/usr/bin/env perl use FileHandle; # Ed Murphy's program to rewrite the orbit page # Updated 03/27/00 Changed GSOC to Heavens Above $output_filename = "/data2/violet/htdocs/users/orbit.html"; open (OUTF, ">$output_filename") || die "Cannot open $output_filename file"; system("chmod ug+rw $output_filename"); system("chgrp www $output_filename"); $input_filename = "@DATADIR@/calfiles/FUSE.TLE"; open (INP_TLE, "<$input_filename") || die "Cannot open $input_filename file"; $satid = 25791; &input_lines; close (INP_TLE); &parse_lines; &convert_doy; &convert_dayfrac; &calculate_a0; &calculate_orbs; $now=`date`; $datest = substr($now,4,3)." ".substr($now,8,2).", ".substr($now,24,4); print OUTF "\n"; print OUTF "\n"; print OUTF "FUSE Orbital Elements page\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "
\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "
\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "
\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "\n"; print OUTF "FUSE

\n"; print OUTF "Orbital Elements\n"; print OUTF "

\n"; print OUTF "\n"; print OUTF "

\n"; print OUTF "

\n"; print OUTF "\n"; print OUTF "Where is FUSE now?
\n"; print OUTF "Check out the\n"; print OUTF "\n"; print OUTF "Heavens-Above Satellite Predictions page .\n"; print OUTF "
\n"; print OUTF "

\n"; print OUTF "

\n"; print OUTF "

\n";
print OUTF " \n";
print OUTF  "FUSE orbital elements:\n";
print OUTF  "     NORAD number       25791\n";
print OUTF  "     International ID  99035A\n";
print OUTF  " \n";

&print_orb;

print OUTF "
\n"; &print_tail; close (OUTF); ### end of Perl script sub convert_doy { @daytab1 = (0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); @daytab2 = (0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); @monthstr = ("", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"); if ((($year%4 == 0) && ($year%100 != 0)) || ($year%400 == 0)) { # $year is a leap year use daytab1 for ($i = 1; $doy > $daytab1[$i]; $i++) { $doy -= $daytab1[$i]; } } else { # $year is not a leap year, use daytab2 for ($i = 1; $doy > $daytab2[$i]; $i++) { $doy -= $daytab2[$i]; } } $month = $monthstr[$i]; $day = $doy; } sub convert_dayfrac { $dayfrac *= 24.0; $hour = int($dayfrac); $minute = int(($dayfrac-$hour)*60.0); $second = ((($dayfrac-$hour)*60.0)-$minute)*60.0; } sub input_lines { $line1 = ; $line2 = ; $line3 = ; $id2 = substr($line2, 2, 5); $id3 = substr($line3, 2, 5); if (($id2 != $satid) || ($id3 != $satid)) { print STDOUT "Error in TLE:\n"; print STDOUT $line1; print STDOUT $line2; print STDOUT $line3; # die "Error in TLE"; } } sub parse_lines { $year = substr($line2, 18, 2); $doy = substr($line2, 20, 3); $dayfrac = substr($line2, 23, 9); $epoch = $year.$doy.$dayfrac; $incl = substr($line3, 9, 8); $raan = substr($line3, 17,8); $eccen = substr($line3, 26, 7); $eccen = "0." . $eccen; $mean_mot = substr($line3, 52, 11); $mean_anom = substr($line3, 43, 8); $arg_perig = substr($line3, 34, 8); if ($year > 50) { $year += 1900; } else { $year += 2000; } $dayfrac = "0".$dayfrac; } sub calculate_a0 { $mu = 3.986005E5; $pi = 3.14159265358979; $radian = 0.0174532925200; $mm=2.0*$pi*$mean_mot/(24.0*60.0); $ke=0.74366916E-1; $k2=5.413080E-4; $a1=($ke/$mm)**(2.0/3.0); $inrad = $incl * $radian; $d1=3.0/2.0*$k2/($a1*$a1)*(3.0*cos($inrad)*cos($inrad)-1.0)/((1.0-$eccen*$eccen)**(3.0/2.0)); $a0=$a1*(1.0-$d1/3.0-$d1*$d1-134.0/81.0*$d1*$d1*$d1); $d0=3.0/2.0*$k2/($a0*$a0)*(3.0*cos($inrad)*cos($inrad)-1.0)/((1.0-$eccen*$eccen)**(3.0/2.0)); $semiax=$a0/(1-$d0)*6378.135; } sub calculate_orbs { $period = 60.0*24.0/($mean_mot/(1+$d0)); $cax=$eccen*$semiax; $perigee=$semiax-$cax-6378.1; $apogee=$semiax+$cax-6378.1; } sub print_orb { print OUTF " Epoch $epoch\n"; printf OUTF " Semimajor axis %7.2f km\n",$semiax; printf OUTF " Apogee %5.2f km\n",$apogee; printf OUTF " Perigee %5.2f km\n",$perigee; print OUTF " Eccentricity $eccen\n"; printf OUTF " Inclination %6.2f degrees\n",$incl; printf OUTF " Period %6.2f minutes\n",$period; printf OUTF " RA of asc. node %6.2f degrees\n",$raan; printf OUTF " Arg. of perigee %6.2f degrees\n",$arg_perig; printf OUTF " Mean anomaly %6.2f degrees\n",$mean_anom; print OUTF " \n"; } sub print_tail { print OUTF "

"; print OUTF "The FUSE Delta II second stage (NORAD #25792) reentered on \n"; print OUTF "the morning of August 4, 1999 during orbit number 708. \n"; print OUTF "According to predictions by Alan Pickup, reentry \n"; print OUTF "occured within 90 minutes of 5:31 UT, probably over the \n"; print OUTF "Arabian Sea or India. The final orbit was 119 x 103 km (74 x 64 mi).\n"; print OUTF "

"; print OUTF "

"; print OUTF "\n"; print OUTF " Could anything have survived reentry?

\n"; print OUTF "

"; print OUTF "\n"; print OUTF "

These numbers assume a Keplerian orbit; the actual apogee and perigee \n"; print OUTF "will differ by a few km on an orbit-to-orbit basis.\n"; print OUTF "

"; print OUTF "

The NORAD Two-Line Elements (TLEs) for FUSE can be found in the file \n"; print OUTF " FUSE.TLE .\n"; print OUTF "

\n"; print OUTF "This page is automatically updated daily. I wish to thank \n"; print OUTF "Doyle Groves \n"; print OUTF "for providing a Perl script to access the NASA\n"; print OUTF "Orbital Information Group web page.\n"; print OUTF "

Ed Murphy, \n"; print OUTF "

emurphy\@pha.jhu.edu
\n"; print OUTF "

\n"; print OUTF "\n"; print OUTF "

\n"; print OUTF "Last changed: $datest.\n"; print OUTF "

\n"; print OUTF "Return to the FUSE home page.
\n"; print OUTF "

\n"; print OUTF "

\n"; print OUTF "
\n"; print OUTF "\n"; print OUTF "\n"; }