The principal analytical photogrammetric tools being employed 
in the reduction of Apollo 15 photography and data are computer 
programs LOSAT (Lunar Orbiter. Strip Analytical Triangulation) and 
LOBAT (Lunar Orbiter Block Analytical Triangulation) developed by 
DBA Systems, Inc. The programs treat position, velocity, time of 
exposure, orientation angles and photographic point measurements 
as observed quantities subject to a priori constraints and perform 
a rigorous least squares adjustment of photographic strips and 
blocks. Uniquely, they provide application of short arc, dynamical 
constraints and confine exposure stations to lie on orbital arcs 
defined by the equations of motion. Independent LOSAT solutions 
are being developed for each of 14 orbital revolutions of the 
vertical photography acquired by Apollo Mission 15. Individual 
strips generally contain 145 photographs and alternate frames are, 
being employed to develop a triangulation incorporating observations 
from 850 terrain and companion stellar photographs. It is planned 
that 17 sub-block solutions will be performed for data edit and 
that upon evaluation and resolution of inter-orbit differences, 
selected photo strip segments (containing 300-500 photographs) will 
be combined in a single block solution. The parameters of this 
solution will provide the basis for computation of a consistent 
control point network covering 10Z of the lunar surface with a 
density of 1 point per 900 square kilometers. 
Triangulation testing of the seven exposure segments of the 
three test strips has allowed a limited evaluation of the compat- 
ibility of position, orientation and photo mensuration data.  LOSAT 
solutions in which photo measurements and orientation angles are 
weighted in accordance with defined accuracies, reflect a necessity 
for a change in spacecraft velocity of approximately 1 meter/second. 
Extrapolation of this velocity change to a full orbital arc con- 
taining 145 exposures accomplished at an interval of 23 seconds 
would change arc length by over 3 kilometers, requiring reshaping of 
the orbit to establish exposure statión positions which are con- 
sistent with other data inputs. Comparison of common surface 
positions developed from the short test strips, shows biases in the 
order of 50 meters for elevations derived from different photographic 
revolutions. Systematic horizontal displacements range from 250 
meters between revolutions 22 and 27 solutions to 650 meters between 
revolutions 22 and 60 solutions. The time interval between 
revolution 22 and 27 photography was 10 hours, while 75 hours 
separated orbital revolutions 22 and 60. These early results, 
based on 21 exposures from 3 lunar orbital arcs can only be con- 
sidered indicative of a significant lack of compatibility between 
the developed spacecraft ephemeris and photogrammetric data. 
Triangulation of the full length of the overlapping, orbital photo- 
graphic strips will be required to adequately describe discontinuities 
and identify their source. Hopefully, these photogrammetric 
definitions of systematic differences in orbital and surface positions 
will lead to an improved lunar gravity model and knowledge of seleno- 
detic parameters as a basis for further control development. 
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