Vehicle Earth Parking Orbit Configuration

(saturn v third stage and instrument unit, apollo spacecraft)

post t.li -timeline

TLI + 20 SEC LOCAL . , HORIZONTAL ORBIT RATE

TLI + 15 MIN / MANEUVER TO As SEPARATION ^ ATTITUDE

TLI+ 25 MIN SC INITIAL SEPARATION (1 FPS)

TLI + 20 SEC LOCAL . , HORIZONTAL ORBIT RATE

TLI+ 25 MIN SC INITIAL SEPARATION (1 FPS)

TLI + 27 MIN NULL SEPARATION RATE AND PITCH TO DOCKING ATTITUDE

TLI + 90 MIN LM WITHDRAWAL

TLI + 27 MIN NULL SEPARATION RATE AND PITCH TO DOCKING ATTITUDE

TLI + 90 MIN LM WITHDRAWAL

SPS EVASIVE MANEUVER -20 FPS

Translunar Coast

Up to four midcourse correction burns are planned during the translunar coast phase, depending upon the accuracy of the trajectory resulting from the TLI maneuver. If required, the midcourse correction burns are planned at TLI +9 hours, TLI +2 4 hours, lunar orbit insertion (LOI) -22 hours and LOI -5 hours.

During coast periods between midcourse corrections, the spacecraft will be in the passive thermal control (PTC) or "barbecue" mode in which the spacecraft will rotate slowly about one axis to stabilize spacecraft thermal response to the continuous solar exposure.

Lunar Orbit Insertion (LOI)

The first of two lunar orbit insertion burns' will be made at 75=54:28 GET at an altitude of about 80 nm above the Moon. LOI-1 will have a nominal retrograde velocity change of 2,924 fps and will insert Apollo 11 into a 60xl70-nm elliptical lunar orbit. LOI-2 two orbits later at 80:09=30 GET will adjust the orbit to a 54x65-nm orbit, which because of perturbations of the lunar gravitational potential, will become circular at 60 nm at the time of rendezvous with the LM. The burn will be 157-8 fps retrograde. Both LOI maneuvers will be with the SPS engine near pericynthion when the spacecraft is behind the Moon and out of contact with MSFN stations. After LOI-2 (circularization), the lunar module pilot will enter the lunar module for a brief checkout and return to the command module.

Lunar ModuleDescent, Lunar Landing

The lunar module will be manned and checked out for undock-ing and subsequent landing on the lunar surface at Apollo site 2. Undocking will take place at 100:09=50 GET prior to the MSFN acquisition of signal. A readially downward service module RCS burn of 2.5 fps will place the CSM on an equiperiod orbit with a maximum separation of 2.2 nm one half revolution after the separation maneuver. At this point, on lunar farside, the descent orbit insertion burn (DOI) will be made with the lunar module descent engine firing retrograde 74.2 fps at 101:38:48 GET. The burn will start at 10 per cent throttle for 15 seconds and the remainder at 40 per cent throttle.

The DOI maneuver lowers LM pericynthion to 50,000 feet at a point about 14 degrees uprange of landing site 2.

A three-phase powered descent initiation (PDI) maneuver begins at pericynthion at 102:53:13 GET using the LM descent engine to brake the vehicle out of the descent transfer orbit. The guidance-controlled PDI maneuver starts about 260 nm prior to touchdown, and is in retrograde attitude to reduce velocity to essentially zero at the time vertical descent begins. Spacecraft attitudes range from windows down at the start of PDI, to windows up as the spacecraft reaches 45,000 feet above the lunar surface and LM landing radar data can be integrated by the LM guidance computer. The braking phase ends at about 7,000 feet above the surface and the spacecraft is rotated to an upright windows-forward attitude. The start of the approach phase is called high gate, and the start of the landing phase at 500 feet is called low gate.

Both the approach phase and landing phase allow pilot takeover from guidance control as well as visual evaluation of the landing site. The final vertical descent to touchdown begins at about 150 feet when all forward velocity is nulled out. Vertical descent rate will be three fps. Touchdown will take place at 102:47:11 GET.

LUNAR ORBIT

INSERTION

CI RCULAR1ZATI0N

bhhh« surface darkness sc darkness

^SEPARATION

LM ABOVE AND BEHIND

DIRECTION "r

LM ABOVE AND BEHIND

OF MOTION

0lm (doi) descent orbit insertion maneuver msfn. los

MOTION OF LM RELATIVE TO CSM MOON

landing site

undock

Ocsm/lm\\ os undock

landing site

0CSM separation maneuver (sm rcs)

earth

CSM/LM SEPARATION MANEUVER

0 0

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