The Dark Side of Hardware Upgrade Forum

Riprendo la discussione dell .it sulla sonda Rosetta dell' Agenzia Spaziale Europea, in viaggio per esplorare una cometa.
I post precedenti li trovate su http://www.hwupgrade.it/forum/showthread.php?t=622028

Per chi non sapesse cosa e' Rosetta, quali risultati dovrebbe ottenere, puo' leggerlo direttamente in questo sito dell' ESA.

ROSETTA Mission Operations Report (WOR #150)
Period : 17 January 2011 – 25 January 2011


1 Summary of Activities
During the reporting period ca. 98% of Rendezvous Manoeuvre 1 (RDVM#1, total ca. 780 m/s) was completed with a sequence of 6 burns (details in appendix). During the 2nd planned burn the spacecraft suffered a safe mode due to a large misperformance of the RCS subsystem (SC AR-207). The spacecraft was promptly recovered and a new operations strategy for the RCS was implemented by the Mission Control Team at ESOC to prevent the problem. In view of the major problems observed the manoeuvre and its split had to be re-designed and was then completed with the use of the redundant set of thrusters. Spacecraft behaviour was not nominal also with the use of the new operating mode and the redundant set of thrusters (SC AR-208), however the re-planned burns could be completed successfully. The spacecraft is currently in nominal status and on track to perform the final trim manoeuvre (17.6 m/s TBC, ca. 2% of the total) on the 10th of February.
At the end of the reporting period (DoY 024) Rosetta was at 598.2 million km from the Earth (3.99 AU); one-way signal travel time was 33 min 16 sec (1996 sec). The distance to Sun was 583 million km (3.90 AU).

DoY Date Pass Activity
017 17/01/11 DSS-26 2519 NNO 2529 RDVM#1 Burn 1A (300 m/s)
018 18/01/11 DSS-24 2520 NNO 2520 RDVM#1 Burn 1B (274 m/s interrupted by Safe Mode after ca. 30 m/s)
019 19/01/11 DSS-24 2521 NNO 2521 Safe Mode Recovery completion
020 20/01/11 DSS-25 2522 NNO 2522 RCS Reconfiguration and RCS B performance test
021 21/01/11 DSS-24 2523 NNO 2523 RDVM#1 Test Burn (35 m/s)
022 22/01/11 DSS-25 2524 NNO 2524 RDVM#1 Burn 2A (160 m/s)
023 23/01/11 DSS-65 2525 NNO 2525 RDVM#1 Burn 2B (200 m/s)
024 24/01/11 DSS-26 2526 NNO 2526 RDVM#1 Burn 2C (45 m/s)

2 Satellite Status
2.1 Platform
2.1.1 AOCS / RCS
The AOCS configuration at the end of the reporting period is:
- AOCS in NM / attitude control based on wheels since DoY 2010.027.15.50.
- RCS: thrusters B nominal, A redundant. A misperformance of the subsystem (likely thruster 9A) led to an attitude offpointing and then a level 2 Safe Mode during burn 1B on DoY 2011.018.19.51.27. After the Safe Mode RCS performance tables have been scaled down to pressure levels at beginning of subsequent test burn and the blowdown factor was adapted at each manoeuvre. Last commanded value was 0.852 on 024/2011 for burn 2C.
- Gyros: IMP A (meas) ON (since DoY 258/2010), IMP B (red) OFF (since DoY 258/2010), IMP C (verif) ON (since DOY 006/2011).
- Reaction Wheels: wheels A, C, and D ON since DoY 2010.027.15:15. RW B is OFF since DoY 196.2010. Attitude control on 3 reaction wheels since DoY 196. Erratic behaviour of RW C continues. The use of RWs in Safe Mode is disabled since DoY 317/2010.
- ACM-A and B ON continuously.
- Star Tracker A in use (since DOY 257/2009). STR A ON since DoY 259/2010. STR B OFF since DoY 331/2009. Both units run SW 2.8.
- NAVCAM A and B OFF since DoY 191/2010.
- Gyro-stellar estimator ON since DoY 027/2010, gyro-less estimator OFF since DoY 251/2009.
- Auto-WOL and RW reconfiguration disabled (since DOY 297/2010).
- Deep Space flag set to TRUE (since DOY 298/2006)
- The SAS luminance thresholds are set as follows since DoY 335/2009:
• Sun presence 0.0009 A
• angular validity 0.000125 A
- The AOCS SW is in normal configuration (i.e. patch 12 not installed) since DoY 013/2010.

The current guidance options are set as follows (since DOY 194/2010):
NM: X Earth pointing, Y axis perp to Ecliptic Plane, +Y North [EEN]
Ref. axis [cos(35), 0, sin(35)]
i.e. Earth pointing with 35 deg bias in +X/+Z quadrant
SHM: same as NM

2.1.2 TT&C
The performance of the subsystem is nominal. The subsystem is configured for Active Cruise configuration since DOY 027/2010:
- TRSP-2 X-band up and down via HGA, 14 kbps downlink, 2 kbps uplink
- Back-up is configured for S-band reception at 7.8 bps via LGA-F as from DoY 355/2009.

2.1.3 Thermal
The thermal behaviour of the spacecraft is nominal and stable.
The HW controlled heaters are in ACM2 configuration since DoY 075/2010.
The TCT SW is configured for Intermediate Sun distance (ITM) conditions since DoY 013/2010. On DoY 068/2010 the upper limit of lines 35/36 (CAMs) was lowered from 15 to 5 degC to reduce the warm pixels. This setting will be will be made permanent.
TCT line 34 (STR 2) is still declared as “both heaters failed” due to current spacecraft attitude; it will be reconfigured back to nominal after the SC is returned in its normal attitude at the end of RDVM#1 activities.
Since DoY 330/2010 active temperature control for both propellant tanks is as follows:
- MMH: 14.5-15.5 degC with TCS heater controlled by TCT
- NTO: 24.3-25 degC with TCS heater permanently ON and nominal gauging heater controlled by TCT with control on gauging thermistors;

2.1.4 Power
The subsystem is in its nominal configuration and performing nominally.
During the burns of RDVM#1 it could be noticed that residuals coming from the attitude control thrusters are deposited on the solar arrays. This is visible as follows:
- after the end of the manoeuvres the spacecraft (RWs) has to compensate an external torque around the Z axis (see also plot in appendix 1)
- the short-circuit current monitoring strings show large variations during and after the manoevres; this is mainly visible on the +Y wing and it is consistent with the thrusters couple that is firing (5 with deposits on the front side of +Y wing, and 3 with deposits on the back side of –Y wing).
The actual behaviour of the +Y cells is not fully understood; it also remains to be assessed if this has a permanent effect on the overall arrays performance.

2.1.5 Data handling
The subsystem is in its nominal hardware and software (v7) configuration. SSMM runs SW version 1.6 since DOY 159/2005. The TC link monitor time-out is set to 7 days since DoY 312/2010. The TM generation mode is configured to “Weekly mode” since DoY 304/2010. The System Init Table (SIT) is in “Normal” configuration since DoY 013/2010.
The X-band Safe Mode is enabled since DoY 029/2010. Use of this new Safe Mode configuration was unintentionally tested in occasion of the Safe Mode of DoY 018. The validity of the concept and the results in terms of recovery time have been proved by the rest of the RDVM#1 sequence.
The strobing flag in the call to the Safe/Survival Mode OBCP is set to MGA since DoY 343/2009.
The DSHAP step counter is set to 12 since DoY 036/2010.

2.1.6 Mechanisms
All mechanisms are performing nominally.
The SADM is ON since DoY 027/2010 after DSHM exit.
The APM is ON since DoY 027/2010 after DSHM exit.

2.2 Payload
ALICE The instrument is currently OFF
CONSERT The instrument is currently OFF.
COSIMA The instrument is currently OFF.
GIADA The instrument is currently OFF.
MIDAS The instrument is currently OFF.
MIRO The instrument is currently OFF.
OSIRIS The instrument is currently OFF.
ROSINA The instrument is currently OFF.
RPC The instrument is currently OFF.
RSI The USO is ON/muted since DoY 032/2010.
VIRTIS The instrument is currently OFF.
LANDER Philae The instrument is currently OFF.
SREM The instrument is ON with standard settings since DoY 032/2010.

Ground Facilities
Ground Stations
During the reporting period mission operations have been conducted with the ESA New Norcia ground station and several antennas of the NASA DSN network without problems.

Future Milestones
The spacecraft trajectory is now carefully analysed to assess the exact performance of the bulk of RDVM#1. Once this assessment is done, the trim manoeuvre, planned for the 10th of February with a nominal DV of 17.6 m/s, will be finalised in terms of magnitude and direction. Eventual residuals will be cleared with a second trim manoeuvre in March.


Riassunto: comandata una ampia manovra. Durante lo svolgimento si sono manifestati problemi, superati con tanta fatica.
Alla fine, la manovra e' stata eseguita come previsto e con notevole precisione.

Visto che è un thread nuovo, almenoscriviamoci di cosa parla, così non bisogna andare "di là" per scoprirlo!

VIAGGIO

Il viaggio di Rosetta durerà circa 10 anni, e coprirà una distanza massima dal sole di circa 5,25 unità astronomiche (UA, pressapoco 790 milioni di km).

Lancio: (Febbraio 2004)
Primo passaggio della Terra: (Novembre 2005)
Passaggio di Marte: (Febbraio 2007)
Secondo passaggio della Terra: (Novembre 2007)
Terzo passaggio della Terra: (Novembre 2009)
Ibernazione nello spazio profondo: (Maggio 2011 - Giugno 2014) <<<<---- Stato attuale

Intercettazione cometa: (Gennaio-Maggio 2014)
Mappatura/caratterizzazione cometa: (Agosto 2014)
Atterragio del lander sulla cometa: (Novembre 2014)
Inseguimento attorno al sole: (Novembre 2014 - Dicembre 2015)

Rosetta seguirà quindi la cometa 67P/Churyumov-Gerasimenko nella sua orbita ciclica attorno al Sole, osservando cosa succede al suo nucleo giacciato mentre incontra la stella e si allontana.

La missione termina nel dicembre 2015.

per capire, nel piu ottimistico dei casi, quali sono i dati utili che ci si aspetta di raccogliere (o si è già raccolti) da questa missione?

E, scusate la mia stupidità, ma un corpo ghiacciato che si avvicina al sole quante cose potrebbe fare a parte perdere un parte di massa per effetto dell'evaporazione (scioglimento?)

"Si dice" che le comete potrebbero aver portato la vita sulla Terra, ma non è dimostrato; ergo, sulle comete potrebbero esserci composti organici, aminoacidi, magari addirittura DNA...
In ogni caso, contengono il materiale originario da cui si è formato il sistema solare, la cui analisi puo' quindi aiutarci a comprendere meglio come si formo'.
Poi si puo' capire quanto "densa" e "robusta" è una cometa: hai visto mai dovesse servire si "sgretolarne" una...


E' proprio quello che vogliono studiare! Come la perde, quanta ne perde, COSA perde,....
Comunque non si scioglie, perche' nello spazio non c'e' pressione atmosferica, quindi passa direttamente da ghiaccio a vapore ("sublimazione").

Il lancio e' stato il 2 marzo 2004 , non febbraio

Copiator non porta pena...

ROSETTA Mission Operations Report (WOR #154)- 05 March 2011/ 28 March 2011

1 Summary of Activities
The reporting period has seen the execution of the last payload hibernation preparatory activities with the activation of MIDAS, ALICE, and OSIRIS. The full payload complement is now ready for hibernation. The target comet and the sky seen during the approach phase in summer 2014 have been imaged both with OSIRIS and the NAVCAMs in preparation of the scientific mission. During this activity an anomalous acceleration of the spacecraft was observed, most likely due to outgassing of products accumulated during the big rendezvous manoeuvre in January (see appendix 2). In preparation of the hibernation entry manoeuvre characterisation of the spacecraft inertia and of the Sun Acquisition Sensors were conducted.
At the end of the reporting period (DoY 087) Rosetta was at 502 million km from the Earth (3.36 AU); one-way signal travel time was 27 min 58 sec (1678 sec). The distance to Sun was 625.8 million km (4.18 AU).

2 Satellite Status

2.1 Platform
2.1.1 AOCS / RCS
The AOCS configuration at the end of the reporting period is:
? AOCS in NM / attitude control based on wheels since DoY 2010.027.15.50.
? RCS: thrusters A nominal, B redundant.
? Gyros: IMP A (meas) ON (since DoY 258/2010), IMP B (red) OFF (since DoY 258/2010), IMP C (verif) OFF (since DOY 063/2011).
? Reaction Wheels: wheels A, C, and D ON since DoY 2010.027.15:15. RW B is OFF since DoY 196.2010. Attitude control on 3 reaction wheels since DoY 196. The use of RWs in Safe Mode is disabled since DoY 317/2010. During the observation activities of DoY 085 and 086 (Sun at -60deg in +X/-Z quadrant) the wheels were subject to an unexpected speed profile due to the torques acting on the spacecraft mainly around Y and X axes; the total absence of torques around Z leads to think that torques were given by material coming out of the –Z face of the spacecraft. This event can also be correlated with an anomalous acceleration of the spacecraft and is suspected to be due to outgassing. Data are being processed and analysed but the most likely cause is outgassing of deposits from the RDVM.
? ACM-A and B ON continuously. ? Star Tracker A in use (since DOY 257/2009). STR A ON since DoY 259/2010. STR B OFF
since DoY 331/2009. Both units run SW 2.8.
? NAVCAM A and B OFF since DoY 086/2011. Both NAVCAMs were activated to image the comet and the sky that will be seen during the approach phase.
? Gyro-stellar estimator ON since DoY 027/2010, gyro-less estimator OFF since DoY 251/2009.
? Auto-WOL and RW reconfiguration disabled (since DOY 297/2010).
? Deep Space flag set to TRUE (since DOY 298/2006)
? The SAS luminance thresholds are set as follows since DoY 335/2009:
• Sun presence 0.0009 A
• angular validity 0.000125 A ?
The AOCS SW is in normal configuration (i.e. patch 12 not installed) since DoY 013/2010.
The current guidance options are set as follows (since DOY 194/2010):
NM: X Earth pointing, Y axis perp to Ecliptic Plane, +Y North [EEN]
Ref. axis [cos(35), 0, sin(35)]
i.e. Earth pointing with 35 deg bias in +X/+Z quadrant

SHM: same as NM

2.1.2 TT&C
The performance of the subsystem is nominal. The subsystem is configured for Active Cruise configuration since DOY 027/2010:
? TRSP-2 X-band up and down via HGA, 22 kbps downlink, 2 kbps uplink
? Back-up is configured for S-band reception at 7.8 bps via LGA-F as from DoY 355/2009.

2.1.3 Thermal
The thermal behaviour of the spacecraft is nominal and stable.
The HW controlled heaters are in ACM2 configuration since DoY 075/2010.
The TCT SW is configured for Sun distance above 4 AU (Cold TCT) since DoY 041/2011. On DoY 068/2010 the upper limit of lines 35/36 (CAMs) was lowered from 15 to 5 degC to reduce the warm pixels. This setting will be will be made permanent.
Since DoY 048/2011 active temperature control for both propellant tanks is as follows:
? MMH: 20 – 20.76 degC with TCS heater controlled by TCT with control on gauging thermistors
? NTO: 20 – 20.76 degC with redundant gauging heater permanently ON and nominal gauging heater controlled by TCT with control on gauging thermistors
This temperature is meant to be maintained during active cruise phases at least till execution of RDVM#2 in 2014, compatibly with the power availability.

2.1.4 Power
The subsystem is in its nominal configuration and performing nominally.
During the SAS characterisation exercise the solar arrays were operated with a Sun aspect angle of 40 deg for ca. 1h30min; in this condition the power availability was more or less exactly what the spacecraft was consuming (ca. 540-560W) with a continuous switching between MPPT and BDR mode due to the large power demand oscillations of the reactions wheels during the manoeuvre. It can be seen how unstable the behaviour of the APRs was; this behaviour will be double checked offline, however the main bus voltage was extremely stable throughout the phase i.e. meaning that the power regulation was stable.
To confirm what seen above, large oscillations were visible on the MEA voltage, arrays voltage (only APR A1 reported), and on the batteries discharge currents (battery 1 reported).
Before the test the End of Charge voltage of all batteries was commanded to level 2 (i.e. 24.24 V) from level 0 (24.7 V) in order to allow a slight discharge in preparation of further arrays performance tests.

2.1.5 Data handling
The subsystem is in its nominal hardware and software (v7) configuration. SSMM runs SW version 1.6 since DOY 159/2005. The TC link monitor time-out is set to 7 days since DoY 312/2010. The TM generation mode is configured to “Weekly mode” since DoY 304/2010. The System Init Table (SIT) is in “Normal” configuration since DoY 013/2010. The X-band Safe Mode is enabled since DoY 029/2010.
The strobing flag in the call to the Safe/Survival Mode OBCP is set to MGA since DoY 343/2009. The DSHAP step counter is set to 12 since DoY 036/2010.

2.1.6 Mechanisms
All mechanisms are performing nominally. The SADM is ON since DoY 027/2010 after DSHM exit. The APM is ON since DoY 027/2010 after DSHM exit.
2.2 Payload
ALICE
The instrument is currently OFF. The instrument was activated on DoY 065 for the last mechanisms actuation before the hibernation phase.
CONSERT The instrument is currently OFF.
COSIMA The instrument is currently OFF.
GIADA The instrument is currently OFF.
MIDAS
The instrument is currently OFF. The instrument was activated on DoY 064 for the last mechanisms/piezos actuation before the hibernation phase. During this activation a small positioning error of the linear stage was observed, most likely due to low temperatures, and later corrected with an activation on DoY 069. The instrument is now ready for hibernation.
MIRO The instrument is currently OFF.
OSIRIS
The instrument is currently OFF. The instrument was activated on DoY 082 for the uplink of modified switch ON/OFF internal sequences to prevent accidental fail safe actuators activation. The activity was followed by comet imaging, approach phase sky imaging, and hibernation preparation activities. The instrument is now ready for hibernation.
ROSINA The instrument is currently OFF.
RPC The instrument is currently OFF.
RSI The USO is ON/muted since DoY 032/2010.
VIRTIS The instrument is currently OFF.
LANDER Philae The instrument is currently OFF.
SREM The instrument is ON with standard settings since DoY 032/2010.

Future Milestones
The spacecraft is now cruising towards the point where it can safely enter the hibernation phase. Data acquired during last tests will be processed and used to tune the hibernation entry operations. The solar arrays will be further tested before hibernation with a simplified procedure.
Summary of next events:
31 March 2011 Solar arrays test @ 4.2 AU
12 April 2011 Start of opposition phase
11 May 2011 Solar arrays test @ 4.35 AU
20 May 2011 End of opposition phase
8 June 2011 Hibernation entry

La manovra di spin-up e la procedura di ibernazione (un modo a bassissimo consumo di energia) sono stati conclusi con successo.

Adesso una settimana di osservazione passiva e poi appuntamento al 20 gennaio 2014 per il risveglio.

Qualche dettaglio QUI

Buon Viaggio, Bella (semi)Addormentata