2012 TC4 Goldstone Radar Observations Planning


Background


2012 TC4 was discovered by Pan-STARRS 1 on October 5, 2012. 
2012 TC4 will approach Earth within 0.25 lunar distances (LD) on Oct 12, 2012 when it will be an outstanding 
radar target at Goldstone.  

The current orbital solution (solution 11) indicates that 2012 TC4 approached Earth within five lunar distances
(and possibly much closer) in October of 1996 and that it may approach within about 0.37 lunar distances
in October of 2017.

2012 TC4 is on NASA's Near-Earth Object Risk Page (http://neo.jpl.nasa.gov/risk/).  There are 60 potential 
impacts between 2020-2106 for a cumulative impact probability of 3.7x10^-5.  That's a small number, but it's
large enough that radar astrometry will be of considerable interest and it could 
improve the orbit sufficiently to rule out many potential impact trajectories.  That said, it is still
much more dangerous to walk across the street.

Not much is known about this object, except that its absolute magnitude of 26.5 suggests a
a diameter within a factor of two of about 15 meters.
J. Briggs, P. Wiggins, R. Miles, A. Carbognani, W. Ryan, and P. Bacci (pers. comm.) have reported a 
rotation period of 0.2 h and a large lightcurve amplitude of nearly one magnitude.  This indicates that
2012 TC4 is an elongated and rapidly rotating object.  In addition, a second period is present in
the lightcurves that hints that the object could be a non-principal axis rotator (i.e., a tumbler).
Due to the rotation period and our guess about its size, we expect a bandwidth of 5-10 Hz. 

Due to the short notice, there is only one track scheduled on Oct 11 when the object is inbound
at a range of about 1.4 lunar distances.  
As a result of the very short RTT (~3.6 sec), the observations will be bistatic with DSS-14 transmiting and DSS-13 receiving. 
We are planning to obtain CW and 10 and 11 usec ranging data, and if SNRs are significantly stronger
than we expect, we *hope* to utilize the highest resolution available from the chirp system (3.75 m) 
and obtain some delay-Doppler images.  

The S-band radar at Arecibo is undergoing a receiver upgrade and will not be available to observe 2012 TC4.

2012 TC4 brightens below 14th magnitude on the day of the closest approach, after which it moves too close to the Sun
for optical observations.  

The astrometry and lightcurves that have been provided by observers around the world have been invaluable:
Thank you very much!

Orbital and Physical Characteristics  
 orbit type               Apollo
 semimajor axis           1.284 AU     
 eccentricity             0.294 
 inclination              1.4 deg       
 perihelion distance      0.907 AU     
 aphelion distance        1.662 AU     
 absolute magnitude (H)   26.5
 diameter                 ~0.014 km   (within a factor of two)
 rotation period          ~0.2 h (J. Briggs, P.Wiggins, R. Miles, A. Carbognani, W. Ryan, P. Bacci,  pers. comm.) 
 pole direction           unknown
 lightcurve amplitude     ~1 mag  
 spectral class           unknown

Last update: 2012 October 10

Discovery MPEC

M.P.E.C. 2012-T18                                Issued 2012 Oct. 7, 14:42 UT

     The Minor Planet Electronic Circulars contain information on unusual
         minor planets and routine data on comets.  They are published
   on behalf of Commission 20 of the International Astronomical Union by the
          Minor Planet Center, Smithsonian Astrophysical Observatory,
                          Cambridge, MA 02138, U.S.A.

             Prepared using the Tamkin Foundation Computer Network

                              MPC@CFA.HARVARD.EDU
            URL http://www.minorplanetcenter.net/    ISSN 1523-6714

                                   2012 TC4

Observations:
     K12T04C* C2012 10 04.46767323 32 31.445+04 13 34.66         20.1 iLET018F51
     K12T04C  C2012 10 04.47999623 32 29.747+04 13 29.02         20.2 iLET018F51
     K12T04C  C2012 10 06.17441 23 31 27.98 +03 58 15.4          18.8 VrET018703
     K12T04C  C2012 10 06.18227 23 31 26.61 +03 58 10.8          19.0 VrET018703
     K12T04C  C2012 10 06.19686 23 31 23.91 +03 58 03.3          19.0 VrET018703
     K12T04C KC2012 10 06.82657 23 30 47.49 +03 48 25.7                uET018J95
     K12T04C KC2012 10 06.82879 23 30 47.13 +03 48 23.8                uET018J95
     K12T04C KC2012 10 06.83069 23 30 46.85 +03 48 22.3          18.9 RuET018J95
     K12T04C KC2012 10 06.91007 23 30 32.94 +03 47 21.3          18.7 VtET018J84
     K12T04C KC2012 10 06.91735 23 30 31.58 +03 47 15.3          18.5 VtET018J84
     K12T04C KC2012 10 06.92464 23 30 30.16 +03 47 09.2          18.7 VtET018J84
     K12T04C KC2012 10 07.18949 23 30 09.38 +03 44 19.4          17.9 RuET018H36
     K12T04C KC2012 10 07.20168 23 30 06.54 +03 44 08.0          17.9 RuET018H36
     K12T04C KC2012 10 07.21581 23 30 03.30 +03 43 54.5          18.4 RuET018H36
     K12T04C KC2012 10 07.22407 23 29 53.00 +03 43 25.9          19.7 VuET018932
     K12T04C KC2012 10 07.22588 23 29 52.61 +03 43 24.0          19.1 VuET018932
     K12T04C  C2012 10 07.50398 23 29 48.85 +03 39 27.2          19.2 VuET018900
     K12T04C  C2012 10 07.51112 23 29 47.07 +03 39 19.6          18.9 VuET018900
     K12T04C  C2012 10 07.51826 23 29 45.22 +03 39 12.0          19.2 VuET018900

Observer details:
703 Catalina Sky Survey.  Observer A. Boattini.  Measurers A. Boattini,
    E. J. Christensen, A. R. Gibbs, A. D. Grauer, R. E. Hill, R. A. Kowalski,
    S. M. Larson, R. H. McNaught.  0.68-m Schmidt + CCD.
900 Moriyama.  Observer Y. Ikari.  0.26-m f/7.0 reflector + CCD.
932 John J. McCarthy Obs., New Milford.  Observer M. Polansky.  0.4-m f/6.3
    Schmidt-Cassegrain + CCD.
F51 Pan-STARRS 1, Haleakala.  Observers N. Primak, A. Schultz, S. Watters,
    J. Thiel, T. Goggia.  Measurer PS1 Science Consortium.  1.8-m
    Ritchey-Chretien + CCD.
H36 Sandlot Observatory, Scranton.  Observer G. Hug.  0.56-m reflector + CCD.
J84 South Observatory, Clanfield.  Observer D. Briggs.  0.61-m f/4.75
    reflector + CCD.
J95 Great Shefford.  Observer P. Birtwhistle.  0.40-m f/6.0 Schmidt-Cassegrain
    + CCD.

Orbital elements:
2012 TC4                                                 Earth MOID = 0.0001 AU
Epoch 2012 Sept. 30.0 TT = JDT 2456200.5                MPC
M 322.00810              (2000.0)            P               Q
n   0.67724540     Peri.  233.68736     +0.30233884     -0.95316785
a   1.2842178      Node   198.71920     +0.88223745     +0.28295573
e   0.2940961      Incl.    1.40910     +0.36089930     +0.10680409
P   1.46           H   26.6           G   0.15           U   7
Residuals in seconds of arc
121004 F51  0.1+  0.1+    121006 J95  0.2+  0.0     121007 932  0.2-  0.2+
121004 F51  0.2+  0.1+    121006 J84  0.3+  0.1+    121007 932  0.4-  0.2+
121006 703  0.9-  0.5+    121006 J84  0.5+  0.3+    121007 900  0.2+  0.5+
121006 703  0.0   0.5+    121006 J84  0.0   0.4+    121007 900  0.5+  0.2+
121006 703  0.3+  1.9+    121007 H36  0.3-  0.2-    121007 900  0.2+  0.0
121006 J95  0.1+  0.3+    121007 H36  0.2-  0.0
121006 J95  0.1-  0.1+    121007 H36  0.9+  0.1+

Ephemeris:
2012 TC4                 a,e,i = 1.28, 0.29, 1                   q = 0.9065
Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase     V
2012 09 07    23 39 53.0 +04 18 05   0.1469  1.1509   166.2    12.1    23.5
...
2012 09 22    23 37 31.9 +04 40 35   0.07892 1.0821   173.0     6.5    21.8
...
2012 09 30    23 34 53.8 +04 32 18   0.04680 1.0471   167.1    12.3    20.8
...
2012 10 06    23 31 28.9 +04 03 03   0.02371 1.0221   161.0    18.6    19.5
2012 10 07    23 30 22.9 +03 51 25   0.01991 1.0181   159.8    19.9    19.1
2012 10 08    23 28 49.4 +03 34 17   0.01611 1.0141   158.4    21.3    18.7
...
2012 10 14    11 22 02.3 -02 16 56   0.0068230.9915    29.2   150.6    24.3
...
2012 10 22    11 08 11.7 +00 33 15   0.03707 0.9676    41.2   137.4    25.9
...
2012 11 06    11 14 43.3 +00 14 37   0.09493 0.9392    54.4   120.9    26.3

A. U. Tomatic                (C) Copyright 2012 MPC           M.P.E.C. 2012-T18

SNR Calculation

Target Name:   2012 TC4

D = 0.014 km  
Period = 0.2 hr  (lightcurves)  
OC albedo = 0.1
                                                                      Monostatic
                     UT                             #                    max         BISTATIC
DOY  start date    window        RA, dec   dist    runs        SNR     SNR/run        SNR/RTT
-------------------------------------------------------------------------------------------------
284  2012 Oct 10  01:28-10:14    350,  +2  0.008    2306        330         8            2
285  2012 Oct 11  01:20-09:35    346,  -1  0.004    4367       4700        79           20
286  2012 Oct 12  00:59-03:14    311, -28  0.001   12540    1500000     14000         3500
287  2012 Oct 12  15:16-22:01    180, -11  0.002    6937      42000       570          140
288  2012 Oct 13  13:39-21:51    171,  -3  0.006    2861        920        19            5
289  2012 Oct 14  13:18-21:45    169,  -1  0.010    1775        130         3            -

The round-trip time is so short that the observations must be bistatic.
    
Goldstone SNRs assume Ptx = 435 kW 

Track Assignments


Goldstone tracks:

         UT         UT          PST                    Duration    Round-trip     Bistatic
 DOY     Date       TX Window   TX Window                hh:mm     time (sec)     SNR/RTT
 ---     ----       ---------   ---------              ---------    ---------     -------
 285     Oct 11     0545-0935   2245-0235  Oct 10/11     03:50        3.6           ~20
  
NOTE: TXON is shown at the earliest time, which is only 15 min into the precal time.



Uncertainties


From Jon Giorgini, 2012 October 10:

Including the three new measurements forwarded directly by e-mail,
2012 TC4 orbit solution s11 was estimated.  Data arc is 133 optical
from Oct 4-10 2012.

Files were updated on aardvark, .s9 moved to /OLD sub-directory.
Minor noise-level update (below).

3-sigma X-band uncertainties at 4 hour steps:

 Date__(UT)__HR:MN  POS_3sigma   DOP_X_3sig  RT_delay_3sig
 2012-Oct-11 00:00       2.277       181.07       0.002106
 2012-Oct-11 04:00       3.355       179.50       0.001838
 2012-Oct-11 08:00       5.499       177.27       0.001584
 2012-Oct-11 12:00       9.488       173.69       0.001350
 2012-Oct-11 16:00      17.055       167.28       0.001147
 2012-Oct-11 20:00      34.990       152.23       0.000986
 2012-Oct-12 00:00      93.460       127.36       0.000842
 2012-Oct-12 04:00     281.099       493.21       0.000469
 2012-Oct-12 08:00     231.081       365.35       0.000690
 2012-Oct-12 12:00     109.043       193.09       0.001100
 2012-Oct-12 16:00      69.196       172.81       0.001383
 2012-Oct-12 20:00      57.623       171.27       0.001642
 2012-Oct-13 00:00      53.819       176.64       0.001904

Differencing old and new:

     RECEIVER    U.T.         RANGE         DOPPLER     LHA      DEC      RA      EL
s11: 2012 OCT 11 01:30      4.5099030821   391778.316 297.8950  -0.5111 347.766  22.089
s09: 2012 OCT 11 01:30      4.5098652318   391786.844 297.8951  -0.5112 347.766  22.089 
                            ------------   ----------

So + 37.8 usec, -8.5 Hz .... noise levels changes in
s11 relative to s9.

- - - - - - - - - - - - - - - - - - - - 

From Jon Giorgini, 2012 Oct. 10:

With the current dataset of 130 optical measurements spanning 
Oct 4-10, 2012 (including the data forwarded directly), 2012 TC4 
orbit solution #9 was estimated and OSOD w/nominal radar predicts 
established on aardvark in the /2012tc4 sub-directory.

Formal 3-sigma X-band uncertainties for .s9 at 4 hour intervals:

 Date__(UT)__HR:MN  POS_3sigma   DOP_X_3sig  RT_delay_3sig
 2012-Oct-11 00:00       3.194       200.81       0.002149
 2012-Oct-11 04:00       4.815       198.93       0.001872
 2012-Oct-11 08:00       7.842       196.21       0.001618
 2012-Oct-11 12:00      13.409       191.94       0.001399
 2012-Oct-11 16:00      24.019       184.11       0.001228
 2012-Oct-11 20:00      48.903       163.99       0.001114
 2012-Oct-12 00:00     129.091       133.30       0.001003
 2012-Oct-12 04:00     381.490       668.30       0.000513
 2012-Oct-12 08:00     304.256       496.48       0.000916
 2012-Oct-12 12:00     134.199       243.41       0.001463
 2012-Oct-12 16:00      76.439       202.75       0.001810
 2012-Oct-12 20:00      59.462       194.58       0.002113
 2012-Oct-13 00:00      54.843       197.58       0.002409

There is some questionable astrometry which has been deweighted,
but there remains the potential for bias larger than the formal
statistics above.

- - - - - - - - - - 

Uncertainties based on 127 optical observations (6 day data arc), JPL Horizons sol. #7, Oct 10, 2012

 Date__(UT)__HR:MN     POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2012-Oct-09 00:00 *        0.518       59.66      216.82       0.006299
 2012-Oct-10 00:00 *        0.713       59.28      215.45       0.004292
 2012-Oct-11 00:00 *        5.441       58.19      211.48       0.002567
 2012-Oct-12 00:00 *      217.734       56.01      203.57       0.001731
 2012-Oct-13 00:00 *       67.012       57.68      209.65       0.003118
 2012-Oct-14 00:00 *       57.591       59.22      215.23       0.005002
 2012-Oct-15 00:00 *m      57.927       59.85      217.51       0.007046
 2012-Oct-16 00:00 *m      58.269       60.24      218.96       0.009158
 2012-Oct-17 00:00 *m      58.498       60.58      220.17       0.011303

**********************************************************************************************

Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination:

 Date__(UT)__HR:MN     R.A._(J2000.0)_DEC.  APmag            delta     S-O-T /r  T-O-M/Illu%
 2012-Oct-09 00:00     351.59314   3.11045  18.09 0.01232825962405   156.7981 /T  120.4/ 43.4
 2012-Oct-10 00:00     350.45706   2.24106  17.36 0.00854721488741   154.5769 /T  134.2/ 33.7
 2012-Oct-11 00:00     347.54759  -0.00760  16.21 0.00477094120664   150.2789 /T  150.6/ 24.3
 2012-Oct-12 00:00     323.42399 -17.58309  13.84 0.00109824337336   121.1159 /T  165.2/ 15.8
 2012-Oct-13 00:00     176.26647  -6.69283   n.a. 0.00305192311159    21.9380 /L   13.3/  8.6
 2012-Oct-14 00:00     170.51187  -2.28420   n.a. 0.00681428435744    29.2301 /L  8.333/  3.3
 2012-Oct-15 00:00     168.87627  -1.01074   n.a. 0.01058488177640    32.0916 /L   24.8/  0.5
 2012-Oct-16 00:00     168.11436  -0.40923   n.a. 0.01435532506468    33.9609 /L   40.5/  0.4
 2012-Oct-17 00:00     167.68449  -0.06173   n.a. 0.01812675220229    35.4495 /L   56.0/  3.3 

Setups



We're going to attempt 20 MHz chirping.  If the SNRs are sufficiently strong, we hope to try 40 MHz chirping. 

We're going to start with unhopped CW, update the ephemeris, do more CW to 
verify the new solution, and then decide what do do next depending on the SNRs.
If the SNRs are stronger than we expect, we may try imaging.  
Regardless, we plan to do a block of at least 45 minutes of CW with the
updated solution at some point in order to cover multiple rotations by the asteroid.

20 MHz chirp:
-------------
sample clock at 40 MHz, prp 50 us, offset +40 Hz, 2000 bins in delay, FFT=500, ncoh=40  (0.025usx1 Hz)

40 MHz chirp:
-------------
sample clock at 40 MHz, prp 50 us, offset +40 Hz, 2000 bins in delay, FFT=500, ncoh=40  (0.025usx1 Hz)



This object has large Doppler uncertainties, and we may see a Doppler correction
of up to several hundred Hz, so we're going to start with a wider bandwidth than usual:

TX polarization           RCP
RCV polarization          LCP & RCP
Frequency hops:           no hops 
Bandwidth:                8000 Hz
TX Offset:               + 1kHz 
Sampling interval:        1250 x 0.1 usec
VME FFT for PSD files:    8192 for 0.98-Hz resolution 

Once we improve the solution, we'll switch to:

TX polarization           RCP
RCV polarization          LCP & RCP
Frequency hops:           no hops                
Bandwidth:                4000 Hz
TX Offset:               + 1 kHz 
Sampling interval:        2500 x 0.1 usec
VME FFT for PSD files:    4096 for 0.98-Hz resolution 

Ranging setups:
---------------------------------------------------------------------------
10-usec
baud             10 usec
code            127
PRP            1270 usec
FFT             128   
ncoh              1 
bandwidth       787 Hz   
resolution      6.15 Hz
TXOFF          +100Hz  (echo in bin 64+16=80)
---------------------------------------------------------------------------
11-usec 
baud             11 usec
code            127
PRP            1397 usec
FFT             128  
ncoh              1 
bandwidth       716 Hz   
resolution      5.6 Hz
TXOFF          +100 Hz  (echo in bin 64+18=82) 
-------------------------------------------------------------------------
1-usec 
baud            1 usec
code            255
FFT             128
ncoh             6
bandwidth        654 Hz   
resolution       5.1 Hz
TXOFF           +80 Hz -> echo would be centered at 64 + 16 = 80

_____________________________________________________________________
POSSIBLE RANGING SETUPS: (code=127, FFT=64, single-pol'n) 
   These are from JX, w/ max-band (min-acc) options from Ray Jurgens.
   Currently configured for 5-sec records.
_______________________________________________________________________
 Setup        Baud        RP         1-acc 1-acc      
            usec   m      usec        band   res    acc  band     res 
_______________________________________________________________________
 
JX1XS110  11.000 1650    1397.0      715.8  11.2      2   358     5.6
JX1XS070   7.000 1050     889.0     1124.9  17.6      3   375     5.9
                                                      
JX1XS020   2.000  300     254.0     3937.0  61.5     12   328     5.1
                                                      4   984    15.4 

JX1XS010   1.000  150     127.0     7874.0 123.0     41   192     3.0 
                                                      8   984    15.4 

JX1XS005   0.500   75      63.5    15748.0 246.1    123   128     2.0 
                                                     15  1050    16.4 

JX1XS002   0.250   37.5    31.75   31496.1 492.1    492    64     1.0
                                                     30  1050    16.4 
 
JX1XS001   0.125   18.75   15.875  62992.1 984.3   1970    32     0.5 
                                                     60  1050    16.4 
____________________________________________________________________


Instructions

NOTE: Data should be moved to the appropriate subdirectories in aardvark:/export/data0/2012TC4/raw/

2012 TC4 POINTING:

  OSOD and predicts are on aardvark:

Binary-phase coding:
/export/data3/osod/ops/2012tc4/PRDX.OUT.14f-13-13.s11
                              PUNCH.OUT.14f-13-13.s11
                                EPH.OUT.s11

New waveform generator:

/export/data3/osod/ops/2012tc4/PRDX.OUT.14v-13-13.s11
                              PUNCH.OUT.14v-13-13.s11


POINTING  

                                                     TX Offsets    
Date (UTC)   DOY  hhmmss    RA        Dec    Macro   LHA     Dec    RTT    OSOD
2012 10 11   285  050000  346.4945 -1.3029    A                     3.9    11
2012 10 11   285  060000  346.0341 -1.5705    AB     0.5    -0.3    3.8
2012 10 11   285  070000  345.5390 -1.8597    AB     0.5    -0.3    3.6
2012 10 11   285  080000  345.0156 -2.1729     BC                   3.5
2012 10 11   285  090000  344.4702 -2.5129      C    0.5    -0.3    3.3
2012 10 11   285  100000  343.9084 -2.8833      C                   3.2

Transmit offsets are given in millidegrees.  


PRDX.OUT.14f-13-13.s11 TRANSMITTER: STATION #14, RECEIVER: STATION #13 RECEIVER U.T. RANGE DOPPLER LHA DEC RA EL 2012 OCT 11 05:30 3.8657591042 371677.584 359.6524 -1.4325 346.268 53.319 2012 OCT 11 05:40 3.8397435199 370633.519 2.2366 -1.4774 346.191 53.216 2012 OCT 11 05:50 3.8138011431 369589.052 4.8218 -1.5228 346.112 52.954 2012 OCT 11 06:00 3.7879319295 368546.182 7.4080 -1.5688 346.033 52.537 2012 OCT 11 06:10 3.7621357039 367506.906 9.9952 -1.6155 345.953 51.970 2012 OCT 11 06:20 3.7364121404 366473.212 12.5833 -1.6627 345.871 51.258 2012 OCT 11 06:30 3.7107607765 365447.080 15.1723 -1.7106 345.789 50.410 2012 OCT 11 06:40 3.6851810181 364430.475 17.7622 -1.7591 345.706 49.434 2012 OCT 11 06:50 3.6596721241 363425.341 20.3529 -1.8082 345.622 48.339 2012 OCT 11 07:00 3.6342332280 362433.601 22.9445 -1.8580 345.538 47.134 2012 OCT 11 07:10 3.6088633165 361457.149 25.5368 -1.9084 345.452 45.829 2012 OCT 11 07:20 3.5835612638 360497.844 28.1299 -1.9596 345.366 44.431 2012 OCT 11 07:30 3.5583257921 359557.512 30.7237 -2.0114 345.279 42.950 2012 OCT 11 07:40 3.5331555154 358637.938 33.3182 -2.0639 345.191 41.392 2012 OCT 11 07:50 3.5080489195 357740.862 35.9134 -2.1172 345.103 39.766 2012 OCT 11 08:00 3.4830043631 356867.973 38.5092 -2.1711 345.014 38.078 2012 OCT 11 08:10 3.4580200948 356020.912 41.1056 -2.2258 344.924 36.333 2012 OCT 11 08:20 3.4330942469 355201.258 43.7026 -2.2813 344.834 34.539 2012 OCT 11 08:30 3.4082248495 354410.535 46.3001 -2.3375 344.744 32.698 2012 OCT 11 08:40 3.3834098185 353650.201 48.8982 -2.3946 344.652 30.817 2012 OCT 11 08:50 3.3586469765 352921.648 51.4967 -2.4524 344.561 28.899 2012 OCT 11 09:00 3.3339340437 352226.196 54.0957 -2.5111 344.469 26.948 2012 OCT 11 09:10 3.3092686656 351565.093 56.6952 -2.5706 344.376 24.967 2012 OCT 11 09:20 3.2846483892 350939.511 59.2951 -2.6309 344.283 22.959 2012 OCT 11 09:30 3.2600706838 350350.543 61.8954 -2.6921 344.189 20.928 2012 OCT 11 09:40 3.2355329462 349799.198 64.4961 -2.7543 344.096 18.875

2012 TC4 GOLDSTONE MASTERLOG

============================================================================== Receive TX Setup hops dwell code ncoh FFT runs start -stop OSOD offset Poln Notes ------------------------------------------------------------------------------
Dr. Lance A. M. Benner | PHONE: (818) 354-7412 Mail Stop 183-601 | FAX: (818) 393-4445 Jet Propulsion Laboratory | email: lance.benner@jpl.nasa.gov California Institute of Technology | Plan: To live long and prosper Pasadena, CA 91109-8099 http://echo.jpl.nasa.gov/asteroids/2012TC4/2012TC4_planning.html

Asteroid Radar Astronomy
*************************************************************************************************************