FlightGear Forum
Already well advanced into the program, it is almost now normal to see that huge beast taking off as a rocket to reach the Low Earth Orbit,and to come back like a quiet glider, managing is energy with sophisticated tools.
How it was doing that remained fascinating for a lot Passionate people
Every mission was unique and well prepared during months by a whole team. No place for improvisation up there. Ground school, simulator, school again and exams. That was the rude preparation for the chosen astronauts who will reach the space one day.
But also a whole team on the ground: instructor, MCC , engineers, thousands of people working in the shadow to bring that Complex piece of machinery into Orbit, and to bring it back safely again, and again.
A warm and Calm morning on the East Coast, we launch at Dawn today, with a beautiful sky showing all its refraction effects.
Time now for us to take place in Atlantis, which has already a long record of sucessful flight behind her.
The Commander is a veteran from Space program, 5 th time in the Shuttle, probably the last one. Our two mission Specialists coming from France and Japan will assist us during the mission, and will stay then into ISS for half a year.
Finally myself, First time in the Shuttle in the Pilot seat, managing all the engines and APU systems as well as supporting and guiding the Commander during Rendez Vous and Final approach in a couple of days.
Lets seat, T minus 2 hours and a whole lot of things to check
Several checks of the audio system, final IMU alignement, test of the pressurization system and isolation system. Last preparation of the Computer. The GPC 5 is ready and loaded with a back up software in case of major failure with the 4 main one.
If anything weird happens during the ascent, we will just have a few seconds to take over and activate the Back Up Flight System to not loose control of the Orbiter.
T-9 mn, it is closing up
MCC confirmed us that the weather was nominal at KSC, TAL at Zaragoza is a go for weather, as well as all the East Coast US Fields that can allow us to do an emergency landing in case of several engine failures later on.
Essential Bus are connected to their fuel cells, triple redundancy for system that are really important like caution and warning system. I fire up the APU to have Hydraulic Fluid to move the elevons, gimbal the Main Engine Nozzles and Shutoff the Main engine valves at MECO.
Here we are, T-6 s, SSME ignition, Pc over 90 % and Booster ignitions.
3 G's in our face for 2 mn
Lift off !
Quick Glance on the left, everything looks Ok.
We follow the sunrise, magical
Bucket time, Thrust is reduced to break the sound barrier and avoid to blow the Shuttle with the Aerodynamic pressure Peak
Almost 2 mn, Pressure in the Booster decreased below 50 .
Boosters separation is now done, what a weird feeling. No more extra normal G's, and a feeling of silence in the cabin now
I try not to think to much outside of my ascent check to monitor closely.
Everything is under AP, but we have to be ready to face to any caution or warning that may arise
4 mn into the mission, Negative Return. We are to far from KSC to come back in case of Engine Failure, our Speed is now over 8000 ft/s
2 EO Green in the upper part of the CRT above the trajectory.
That is also a good news. Well, sort of. In case of a double engine failure, we will fall back hard into the atmosphere with 2 or 3 G's and may have a chance to make an Emergency Landing on the East Coast of the USA ( or the bailout)
Approaching 12000 ft/s. Another Abort window there. With one engine failure, we can perform an Abort To Orbit ( continue to orbit with degraded performances) and in case of two engine failure, we will not fall below 265 kfeet. So no harsh re entry, but a shallower one and a probable bailout or North East US emergency field.
Also, we are rolling the Shuttle toward the sky. Better communication with TDRS satellites.
We passed 15000 ft/s, almost there and I heard in my helmet "Single Engine ZZA and Press to MECO". Small relief there.
Indeed, it is almost a 100 pages of non normal procedures that are behind us from now on. In case of one engine failure, we can safely reach our targeted Orbit. In case of 2 engine failure, we will do a transoceanic Abort Landing at Zaragoza.
2mn to go, unenventful. Main engines are throttling back to 67 % of max Thrust to avoid to crush the Orbiter with more than 3 longitudinal G's. I always wondered how have they been able to built a such complicated aircraft enveloppe wise.
But here we are, Main Engine Cut Off at 25800 ft/s, less than 10 mn after our Rollercoaster departure.
I can hear the forward RCS firing down while the External Tank separates. We are taking margins with it.
The automatic dump of Liquid Hydrogen and Oxygen that are stuck into the feedlines and Main Engines ( 3 Tons) started.
All Clean Captain. Later on, I will flip wome switches to inert one more time all those feedlines to avoid nasty surprise during re entry ( Hydrogen and atmosphere Oxygen will not go along that well)
Time for a little manoeuver to take a screen of the ET by the upper window for missing foam analysis mainly.
Still a lot to do before the break.
Waiting for the burn that will put us on a stable Orbit ( Our Perigee is at 70 Nm, low to stay in Orbit more than 2 Orbit). I have some work to do, Switching some buttons here and there ( External tank doors closure, heating of the cryo tank, reconfiguring the electric panel , truning off the Main Engine controllers that take more than 2 Kw on the Fuel Cells..)
And the most important one, Shutting Down the APU to preserve the Fuel, deeply needed for Hydraulic assistance during Entry.
A quick look at my check, a "Go for APU Shutdown" from MCC, and there we go
Alright, next step, OMS 2 burn at next Apogee (150 Nm, 50 mnish into the mission)
Today, we fly a very fast rendez vous scenario.
We are almost in plane with ISS ( less than 0.1° of relative inclination) and ISS is 15 ° in front of us.
We are catching her really fast, for a rendez vous in 4 Orbits ( 6 h)
Ignition Time at MET 000/00:55:30, 100ft/s of speed to add in order to increase our Apogee to 120 Nm (TGT) and decrease our catch up rate
Let's enter that, my job.
Item 27 and Digital Autopilot in Auto, Shuttle is now slowly but surely rolling towards its burn attitude, with already the sunset. A sunrise and a sunset in one hour. Unique for sure...
Ignition, good burn, pressure Ok, Parameters in the Green.
Even if Orbital Manoeuvering System are re ignitable, we have a long checklist of failure that may arise ( Propellant Leaks, feedline stuck,Temperature, Helium Leak ...) to react quickly. Propellant is like Gold so far in space. A thousand ft/s of total velocity to play with. No more, no less. Not a lot of room for error.
There we are, 150 Nm by 120Nm Orbit.
Next burn rendez vous at next Apsis in 45 mn.
Now time to change the computer logic from Ascent (OPS1) ot Orbit ( OPS2) one
Quite a long checklist, John Young was right about it, what a non intuitive Computer system it is.
But it is done. GPC 1 and 2 For Guidance, Navigation, and Control of the Orbiter
GPC3 in sleep mode with a copy of orbital software in it ( in case of massive failure of others)
GPC 4 for system management ( Hey GPC 4 , tell me what is the Freon temperature please..)
And GPC 5 in sleep mode also. No Orbit Software was developped for the Back Up Flight Computer.
Also a lot of work for the commander and the mission specialist. Re organisation of The thermal management ( cooling of the Freon using the radiators into the bay), heaters activation for OMS and RCS, payload bay door opening, Star Tracker activation, and shut down of many systems useless for Orbit ( TACAN,MLS, Radar Altimeters,...)
Welcome in Orbit guys
Speaking of Thermal management, a quick look into the SM to check the Freon Temperature. After cooling all the required system, Freon enters the Radiators at 98 °F ( Rad In) and exit them at 58 °F(Rad Out). Good.
H2O loop works as intended ( number 2 only), cooling many systems from avionic bays ( and exchanging is heat to the Freon Loop)
Rest of the paramters are for heaters that work normaly and avoid some freezing waters into the Falsh evaporator system or some too low temperatures in the APU subsystems.
First phasing burn (NC) to come now.
We are less than 2000 kfeet from ISS ( 700 km), coming in low and fast.
Let's raise the Orbit to decrease further more that catch up rate.
Aim on the next burn is to increase the Apogee from 152 to 170 Nm like shown in the TGT section.
MCC and its relative plot is a huge help for us, to have a clear picture of those ground targeted burns and where we are relative to ISS
45 mn of coasting, until next Apsis, the apogee we just created at 170 Nm
Time to review the Rendez Vous procedures, the contigency in case of failure of Star Tracker, Rendez vous Radar, or RCS trouble. Another 200 pages of fun, on which we worked hard during months to be competent the D Day.
Look at that marvelous relativ courb we are flying.
We are coming on a very steep path from behind, just 687 kft ( 200 km from ISS) already.
Time to significantly raise the Perigee now with a Height Adjustment burn (NH)
Perigee of 127 Nm will be raise to 181 Nm ( 3 Nm below ISS) with a burn of 105 ft/s
Thanks to our spatial selfie stick, we can make memorable shots for relatives
Perfect burn, new orbit of 184 by 170 Nm.
It is like an elevator, we slowly rise to ISS to match its orbit and do some fine tuning corrections later on a very close orbit to pinpoint the Rendez Vous. A modern rewrite of Hide And Seek at more than 27 000 Km/h.
And now a very important correction to come.
We still have some relative inclination ( 0.1°), hundreds of feet offset in lateral plan.
To reduce it, we have to make a burn at a node ( where ISS and Shuttle Orbit intersect)
It is very fuel NON efficient, as we have to move the whole state vector into another plan.
Here, 50 ft/s Dv to reduce the Rinc from 0.1 to 0.04....
Planar change burn (NPC)
More than 3 hours since Lift off, and already in the Six of ISS.
Time for a bit of System Management before the next event.
Top CRT, Thermal management as we saw before.
Rad Out T of 28 ° ( we are in the shadow, it helps) I will get an eye on it. I don't want the Freon to Freeze...
And the bottom CRT shows a sum up of essential systems
SMOKE: Monitoring of smoke concentration in the 3 avionic bays ( 2 detector circuit A and B). Nothing to say here, very small concentration of smoke
CABIN: Pressure of 14.7 Psi, nominal. O2 and N2 flow are consistent.
And the right part for differents electrical informations.
3 Fuell cells, hence 3 Main DC bus ( A,B,C) and 3 AC circuit ( 3 phases on each for a maximum of redundance and efficiency)
All the fuell cells are not working at the same rate: 188 Amps for the first, 163 for the second, and 127 for the last one for a total of 14.4 Kw.
No worries here, no need for purge as the voltage seems high enough to not have any contaminations into the electrolyte.
One fuel cell can take care of 8 to 9 kw in normal condition, 12 in emergency for a limited time.
Final phasing burn, real game starts now.
We are 2000 feet below ISS and 373kfeet behind her.
Let's decrease the catch up rate for a two orbit rendez vous from now on ( 3 hours)
Perigee is brought to 178 Nm, Orbit of 182 by 178 after the burn ( plus or minus some Nm due to the Non Spherical Gravity effect with the Earth Beer Belly )
Coasting through the daylight, I can't stop telling myself how lucky we are, all those sacrifices for that..View. A desk with a view I guess
Sun is now down another time, going below 54 Nautical miles of downrange and slowly descending towards our Perigee a couple of thousands feet below ISS.
Our Steep and Low approach is now well behing, time for pinpoint strike.
Everyone is fully working in the cockpit, we know our place and what to do ( I hope)
One thing to take care of now that we are close enough from ISS is to update our propagated State vecor.
Even if our IMU and State vector is very accurate, a couple of feet of error at 27000 ft/s will end up with a huge position error relative to ISS.
To update it, we have on board some filters that will update our propagated State vector into a " normally" better one, called filtered State Vector.
Let's use first the star trackers. They detect source of light and shining objects ( like ISS) based on their magnitude ( up to
they are located in the nose of Orbiter . On on -Y body axes ( pointing left of the Shuttle). The other on the -z axes ( pointing up to the sky from the Shuttle Nose)
They are almost at 90 ° from each others.
We gonna point the - Z towards ISS. Once ISS will be in its field of view, Computes will compare the angle differences between the current Line of SIght when ISS is sensed by the Star tracker and the calculated one using the propagated SV. It is a kind of INS update when we see visually that we are overhead a nav point and that our Navigation system (INS or GPS) tells us that we are 2 miles right of it. Spatial way to update INS and to calculate an angle error with a pointed target between real azimuth and calculated one.
The delta error will be then used to update the state vector more accurately
Commander manoeuvers the Shuttle the point the bay ( hence the top of the nose) towards ISS
And ISS marks can begin every 30 seconds.
Top CRT: Relative Nav software, plenty of infos there
State vector is the propagated one, below we have the calculated range to ISS ( 213000 feet), catch up rate ( 47.5 ft/s), lateral offset Y ( 1.32 feet) and lateral speed Y dot .
Below the filters we talked about ( Star tracker is selected)
Residual of 0.19 degrees ( difference in Line of Sight) So our state vector will be affinate more and more after each mark ( if they are sucessfull). We can also refuse them if we think that the data coming from the filters are not good
Bottom CRT: Star Tracker Software
We can see that the - Z ST is TGT TRK, Tracking a target ie. ISS
Status at the bottom show Hi rate because we are manoeuvering at more than 0.75 deg/s. Once stabilized, it will track again ISS
Very intense work, not time to rest.
We used a lot a software called Orbit target.
It uses Lambert equations to pinpoint the Rendez Vous. Those equations will had a time variable. I am here at time T 1 and I want to be there at time T 2, how do I do ? ( basically)
Some explanations for the bravest
T1 TIG: Time of when we want to make a burn
DX ( downrange), Dz ( height), DY ( cross range) will be the relative position of the Shuttle compared to ISS at Time of Ignition ( in kilo feet)
Dx dot etc will be the relative speed at TIG
The delta position is visible in real time with the canvas on the top right corner.
Now we are 970kfeet behind ISS, 700 feet left of her and 6 kfeet below her.
T2 TIG is the time where we want to be at a specific position relative to ISS
That position is define below with DX,y z.
For example, we can say to the computer : I want to do a burn at T1 07:00, I want to be in one hour T2 08:00 at ISS position, 10 kfeet below ( Dx=0, Dy=0, Dz=-10)
Then Item 28 compute T1 will try to give us a solution in LVLH frame that we can read at the top of the Spec 34 display ( DVX,y,z), automatically transfered to OPS 202 for the burn
Back to the relative navigation page for some additional Star Tracker Mark
In Addition, we have now the Rendez Vous Radar that also calculates some informations ( below 140 kfeet)
It adds some range and data ( below RR GPC) , and also update the state vector to always aim towards a better precision on our position and speed,relatively to ISS
It takes a bit of time to converge, but the filtered state vector is improving well ( 84 kfeet from ISS)
Final coasting phase towards ISS, let's get ready for a close encounter
Finally there, on the V Bar in front of the ISS (2000 feet ahead of ISS)
Now stable, just doing some minor corrections to keep our position, ready to get closer at anytime
And afer a bit of work from the commander, we are slowing going under ISS ( R bar) to dock right below her
Breathtaking, ISS above us at 600 feet, 6 hours after our liftoff from KSC.
Another 30 mn and we will be docked
What a journey, and our mission just began.
We have now to inspect our tiles and finish the docking, but another time
