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Old 12-18-2018, 05:08 PM   #1
Gingin's Avatar
Default STS 88: New Era of Space Exploration ( Mission Sum up )


I just completed Sts 88 mission from the Iss AtoZ Add on https://www.orbiter-forum.com/showthread.php?t=26673
I attached in the poste the link of a modified STS 88 scenario that works for SSU 5 and Orbiter 2016.

What a nice bunch of Add Ons. It is so nice to be able to reproduce those historical missions that made the History.

For more immersion, you can have a look to the STS 88 Press Kit, well done : https://www.jsc.nasa.gov/history/shu..._Press_Kit.pdf

Time Line was delayed by two days due to launch Abort.
I tried to follow the real time line as close as possible with a Rendez Vous on Day three with kind of real Nasa way to perform a Rendez Vous Phasing and burn wise.

Let's jump into the story

I)From Launch To Meco

After several Launch Posponements due to various Reasons ( Hydraulic problems and Launch Window expiration on the last attempt the 03/12), Endeavour was finally Launched the 4th of December 1998 by Night, 08h35mn UTC)

Endeavour on the pad

Liquid Oxygen venting

APU started,LOX Hood removal, Launch is getting closer and no Hydraulics Master Alarm this time

Lift Off of the first mission towards ISS and the Russian Module Zarya, First stage nominal

SRB separation, and second stage for 6 mn before MECO

MECO on time, no underspeed.
Propellant dump begins and we can see some propellant from External Tank being vented to increase the separation and avoid re contact with the Shuttle

II)From MECO To Unity Docking

Zarya is 40 in front of us.
Aim is to perform a rendez vous during start of day 3.
We will pass behind her a first time then come back after a full circle, it will be a 400 phasing on 3 days

One important thing for our goal will be the phasing, to know how much degrees we catch up on Zarya every Orbit.
A very useful graph to help us:

Back to the work

Safely into Orbit now.
Next step will be to raise the Perigee with an OMS 2 burn performed at next Apogee in less than 40 mn

We will circularize the orbit, 124 x 122 Nm to start with. It will give us a 15 phase ( 15 of catch up every orbit)
A fast rate that we will modulate later to slow down.

Post insertion actions are performed waiting for the burn, Like the closing of ET door with a nice back ground

OMS 2 burn in action

Let's start the phasing with a couple of burns
We want to decrease the catch up rate around 10 and have the same line of apside than ISS for easiest Rendez Vous.
A 10 phase will bring us at the end of day 2 close to ISS to start the final orbit adjustement and the rendez vous.
Roughly 37 Orbit to go.

We will then raise the orbit to 154 Nm, almost circular.

Those Phase Adjust Maneuver are called NC1 and performed on target line of apside ( here Zarya Apogee)

NC1 burn raising the apogee at 154 Nm

NC1-1 burn half an orbit later to raise the Perigee to 153 Nm

Here we are, 9 ish of catch up rate on a 154 x 153 Nm orbit sharing same Line of Apsides than Zarya

Time to Deploy the radiators and checked the RMS
A bit of work for the mission specialist

RMS checked and unstowed

Camera OK

Ready to rock for orbital operations

More than a day in Space already

Next burn, the Plane change burn PC to make fully coplanar at a node Chaser and target orbit.
RInc is very low due to a good launch window ( 0.02) and hopefully. We could barely change by more than one degree the inclination with all the propellant available in the Shuttle

Out of Plane (DVy) PC burn

Perfect, phasing is done and Orbit are now coplanar.
We jsut have tot check time to time if we need some corrections to keep Line of node and apsides the same ( due to Non Spherical Gravity or radiation pressure)

Time to Unberth Unity

Not the easiest task that RMS

Joint Coordinates for Unity: Shoulder YAW: -31.16 PITCH: +85.313 Elbow PITCH: -128.6 Wrist PITCH: -74.64 ROLL -216.1 YAW +2.848

Let's dock it to the ODS, not an easy task easier, fine tunning and it works

Joint Coordinates for Unity docked to ODS: Joint Coordinates for Unity: Shoulder YAW: -26.10 PITCH: +113.7 Elbow PITCH: -46.1
Wrist PITCH:-90.15 ROLL :-372.1 YAW -49.44

III)Rendez vous with Zarya

It will be a bit more numerical part now for the final phase of Rendez Vous.

MET 002 /21:16:12
Zaria is closing in, we are just a few degrees behind her.

It is time to stop the phasing phase and reduce greatly the catch up rate to prepare for the final rendez vous phase.

Next burn will be the Height Adjustement ( NH) Burn, raising the apogee within 10 Nm of the target ship.

NH1 Burn, Raising the Apogee to 203 Nm ( it will be the new Perigee later on, 7 Nm below Zarya Perigee of 210 Nm)

NH2 burn 45 mn later, to raise the orbit to 218 x 203 Nm
Same apogee than Zarya and lower Perigee for a shallower catch up rate ( less than a degree/orbit of catch up rate now)

The result here, 400 m (1200ft) below Zarya at Apogee.
NC burn is nicely coming alive now

Alright, almost there.
Now, it is time for Onboard targeted burn based on onboard sensor data ( Star tracker, ranging Radar, COAS eventually)

The aim now is to be in two Orbit below Zarya , on the R bar

Several Burn will happen, NC, NCC, Ti, MC 1 to 4

Here the Theory

Aim is to be 250 kfeet ( 76 km) behind Zarya at next apogee, then one more orbit , and we should be at 50 kfeet ( 14 km ) behind it for Terminal Initiation burn.

What I got in reality after those burn

Spec 34 tool is really well coded and useful if the phasing and height adjustement was properly done. I was a bit close for Nc burn ( 200 kfeet instead of 250 kfeet, but not a big deal, just a less fuel efficient), but the rest of maneuver was very close to the books.

Let's go for the NC burn, we want to be at next apogee ( 91.6 mn period) 48.6 kft behind Zarya (Dx - 48.6), in plane ( Dy 0) and 1200 feet below ( Dz-1.2)

Small Dv, Perigee raised to 206 Nm

NCC burn then. It is a corrective combination that occurs before the next Perigee ( 57.7 mn before next Apogee)
Aim is still the same, to be in a good position at next Apogee for Ti burn.

Dv are very small, either RCS or multi axis burn with Translation RCS. No need for OMS burn at that stage.
Really fine tunning.

Closing in with the next Apogee.
At this stage, either we delay the Rendez Vous by phasing again ( increased Perigee to jave a negative catch up rate) or we go for the Terminal Initiation burn that will lead us to a direct intercept.

The aim here is to be in a good position for the final MC4 burn 320 later ( 76.9 mn)
At that point, we want to be 900 feet behind Zarya ( Dx -0.9) and 1800 feet below (Dz +1.8)

Then 3 Mid course correction to affinate our MC4 Goal.

MC1 not needed

Very small Multi Axis MC2 ( normally burn is not programmed at a specific time , but when Elevation angle between Orbiter's local horizontal and Los to the target vehicule is 28 )

We start to see Zarya in the Back ground

Another small correction for MC 3

MC 4 burn now, 15 mn before Apogee and Rendez vous.
Aim now is to be right below Zarya ( 600 feet, Dz=+0.6) on the R bar in 15 mn.

Here the results after 3 days of orbiting the Earth.
Dtmin of zero, encounter in 15 mn, almost on the same orbit.
I am really amazed by how Spec 34 tool is useful.

Zarya, here we come

IV) Proximity Operations

Finally phase of the Rendez vous, the R bar approach, and station keeping by nullying any residual velocity.

Univ Pointing will help us to track the center of Earth and maintain level wings for a perfect R bar Approach
We can focus on translation only and final approach

Breathtaking, just no words in front of those scenics

Station keeping, RMS work incoming

After pain and tears, Zarya is finally docked to the Unity module

Farewell ISS, see you soon

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Old 12-18-2018, 07:17 PM   #2
Space Cowboy
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Very nice Gingin ! It's like reading these flight reports in aviation !
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Old 12-18-2018, 08:13 PM   #3
Beta Tester


You meant SSU 4.2 correct ?
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Old 12-18-2018, 08:27 PM   #4
Addon Developer
GLS's Avatar

Originally Posted by Donamy View Post
 You meant SSU 4.2 correct ?
That was with the latest revision in the trunk.
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Old 12-18-2018, 08:30 PM   #5
Beta Tester


The payload needs to move back in the bay.
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