Jorge Potti - La misión Rosetta al cometa 67P
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La nave Rosetta de la Agencia Espacial Europea se convirtió en uno de los hitos de la investigación espacial de los últimos años. Fue lanzada el 2 de marzo de 2004 y, tras un viaje de 10 años en los que recorrió 6.400 millones de kilómetros a través del Sistema Solar, llegó a su destino, el cometa 67P/Churyumov-Gerasimenko, el 6 de agosto de 2014. Se convertía así en la primera nave en acoplarse a un cometa y ponerse en su órbita. El 5 de mayo de 2015, la Fundación Ramón Areces dedicó un ciclo de conferencias a analizar esta gesta, en la que participaron los coordinadores científicos de la misión.
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Jorge Potti - La misión Rosetta al cometa 67P
- 1. © GMV, 2015 ROSETTA Y SU LARGO VIAJE DE 10 AÑOS A TRAVÉS DEL SISTEMA SOLAR: UN “BILLAR” CÓSMICO
- 2. © GMV, 2015 GMV Page 2ROSETTA JOURNEY 05/05/2015 americ as Somos una multinacional española, fundada en 1984, con filiales en 11 países y clientes en los 5 continentes. Nuestro origen está ligado a la ESA. Hoy el grupo de empresas proporciona alta tecnología para Espacio, Defensa y Seguridad, Transporte y TIC. 120M€ (facturación) 1,200 empleados 366 satélites con tecnología GMV €
- 3. © GMV, 2015Page 305/05/2015ROSETTA JOURNEY Cometa 67P/Churyumov– Gerasimenko (67P/C-G) Rosetta Philae Asteroid Steins Asteroid Lutetia
- 4. © GMV, 2015 THE ROSETTA JOURNEY CHALLENGE Page 4ROSETTA JOURNEY Rendez-vous and land on a 4 kilometers width comet travelling at a speed of 135,000 km/hour at a distance from Earth in the order of 800 million kms 10 years trajectory travelling 6,400 millions of kms Two Phases: 1. Main Rosetta’s journey (arriving to the comet) 2. Comet proximity operations 05/05/2015 Perihelion distance Aphelion distance Orbital period Nucleus diameter Rotation period Comet CG 1.2 AU 5.7 AU 6.5 years 3-5 km 12.4 h
- 5. © GMV, 2015Page 505/05/2015ROSETTA JOURNEY ROSETTA’S JOURNEY Earth Comet Swing-by
- 6. © GMV, 2015Page 605/05/2015ROSETTA JOURNEY ROSETTA’S JOURNEY …
- 7. © GMV, 2015Page 705/05/2015ROSETTA JOURNEY ROSETTA’S JOURNEY
- 8. © GMV, 2015Page 805/05/2015ROSETTA JOURNEY ROSETTA’S JOURNEY
- 9. © GMV, 2015Page 905/05/2015ROSETTA JOURNEY ARRIVING TO THE COMET
- 10. © GMV, 2015Page 1005/05/2015ROSETTA JOURNEY ARRIVING TO THE COMET
- 11. © GMV, 2015 NAVIGATING AROUND THE COMET Page 11ROSETTA JOURNEY Very challenging: limited a priori knowledge on comet properties with time-varying coma activity and small gravity 05/05/2015 Main tasks: Design the trajectories around the comet Orbit and attitude determination and trajectory reconstruction Image processing for comet detection and landmark identification Estimation of additional comet parameters: mass, gravity field, coma density, center of mass, landmarks Trajectory prediction Manoeuvres optimization Phases: Insertion, initial characterization and global mapping Close observation and lander delivery Relay phase Extended monitoring phase
- 12. © GMV, 2015 INITIAL CHARACTERIZATION, GLOBAL MAPPING AND CLOSE OBSERVATION Initial characterization: Initial estimation of comet characteristics: rotation state, gravity field, shape; first landmarks identification 8 hyperbolic arcs of 3-4 days, flying 2 triangles: first at ~100 km, then ~70 km Global mapping: Map of comet’s surface at 1.5m resolution Gain enough navigation knowledge to fly closer trajectories. Trajectory at 30 km: 3 semi-circular arcs of ~30x30 km quasi-polar orbits of 14 days orbital period -> Trajectory at 20 km (7 days orbital period) Close observation: Detailed observation of landing site and improve navigation accuracy Trajectory: 20x10 and 10x10 km orbit Page 12ROSETTA JOURNEY 05/05/2015
- 13. © GMV, 2015Page 1305/05/2015ROSETTA JOURNEY INITIAL CHARACTERIZATION, GLOBAL MAPPING AND CLOSE OBSERVATION
- 14. © GMV, 2015 CLOSE OBSERVATION, LANDER DELIVERY AND RELAY PHASE Close observation: Detailed observation of landing site, to confirm suitability and refine estimation of comet parameters to improve navigation accuracy Trajectory: 20x10 and 10x10 km orbit in the terminator plane Lander delivery: Deliver lander Philae to the selected landing site From a parking orbit of 30x30 km, pre-delivery manoeuvre to put the S/C in a hyperbolic trajectory with 5 km miss-distance. Lander separates at ~22 km distance Relay Phase: Trajectory: arcs of hyperbolic trajectories to maximize lander visibility to establish communication link Philae–Rosetta–Earth At the end of this phase the spacecraft is back to a 30x30 km parking orbit Page 14ROSETTA JOURNEY 05/05/2015
- 15. © GMV, 2015Page 1505/05/2015ROSETTA JOURNEY CLOSE ORBITS TO LANDER DEPLOYMENT
- 16. © GMV, 2015 EXTENDED MONITORING Escort the comet in its perihelion passage to observe its increasing activity Trajectory: mix of far and close orbits around the comet Page 1605/05/2015ROSETTA JOURNEY
- 17. © GMV, 2015 Gracias Jorge Potti GMV
Notas del editor
- El reto de Rosetta desde el punto de vista de cálculo de trayectorias es descomunal; se trata de alcanzar a un cometa que viaja a 135,000 km/hora y a una distancia de cientos de millones de kms. No sólo alcanzarle sino viajar con él y posar una sonda en su superficie. Tras complejos cálculos la solución a tamaño problema es una trayectoria muy compleja, una de las más compleja jamás realizada, y que supondrá en total un viaje de 12 años y recorrer 6,400 millones de kilómetros; una auténtica salvajada
- La enorme distancia hace que no existan lanzadores suficientemente potentes ni sistemas de propulsión que nos permitan alcanzar un objeto tan distante. Para conseguirlo
- Video 2 min En el video que sigue a continuación se muestra de manera esquemática el viaje compete de Rosetta, desde su lanzamiento en marzo de 2014 hasta el fin nominal de la misión previsto poara finales de este año 2015. Como ya hemos comentado el viajes es una auténtica jugada de billar en la que hemos realizado 3 maniobras asistidas por la gravedad de la Tierra y 1 por la Marte. Además en el mismo sobrevolamos los cometas Steins y Lutetia. En Enero de 2014 Rosetta estaba a 9 millones de kilómetros del cometa. A principios de May de , Rosetta will be 2 million kilometres from the comet and at the end of May the spacecraft will execute a major rendezvous manoeuvre to line it up for orbit insertion at the start of August.
- Video 2 min Rosetta’s journey from launch in March 2004 to comet 67P/Churyumov-Gerasimenko in August 2014, including 3 flybys of Earth and 1 of Mars. By January 2014 Rosetta is about 9 million kilometres from comet 67P/CG. By early May, Rosetta will be 2 million kilometres from the comet and at the end of May the spacecraft will execute a major rendezvous manoeuvre to line it up for orbit insertion at the start of August.
- Video 45 sec En este video observaremos cómo el cometa 67P/Churyumov-Gerasimenko aparece en el campo de vision de la cámara OSIRIS entre los meses de Mayo y Agosto de 2014. Durante esos 4 meses el cometa de 4 kms de tamaño va creciendo desde ser 1 pixel en la cámara a ocupar el campo de visión.
- Video 45 sec Visualisation of how comet 67P/Churyumov-Gerasimenko will appear in Rosetta’s OSIRIS narrow angle camera between May and August 2014. During this time, the 4 kilometre-wide comet will ‘grow’ in Rosetta’s field of view from appearing to have a diameter of less than 1 camera pixel to well over 2000 pixels – equivalent to a resolution of around 2 metres per pixel – allowing the large surface features to be resolved.
- Radiometric observations: Range Doppler Delta-DOR Optical observations: Comet astrometric observations from Earth Comet images from on-board cameras: Direction from S/C to comet centre Directions from S/C to landmarks on comet surface Spacecraft safety: Avoid collision trajectories to the comet Avoid small relative velocities w.r.t. the comet Avoid Sun eclipses Avoid all previous conditions even in the case of an aborted manoeuvre, or being interrupted during execution Navigation accuracy: Reconstruction and prediction of S/C relative trajectory with sufficient accuracy in a range of possible comet environments Pointing error to the comet, up to next data cut-off, should be less than half the FOV of the NAVCAMs
- Video 2 min What happens after Rosetta arrives at comet 67P/Churyumov–Gerasimenko? This animation describes the key dates for the next set of manoeuvres that will bring Rosetta even closer to the comet between August and October. After arriving on 6 August, Rosetta will follow a set of two, three-legged triangular trajectories that require a small thruster burn at each apex. The legs are about 100 km long and it will take Rosetta between three and four days to complete each one. The first triangle is conducted at a distance of about 100 km from the comet, the second at around 50 km. Then Rosetta will switch to a ‘global mapping phase’ at an altitude of about 30 km. During this period, it will make a ‘night excursion’, whereby the ground track of the spacecraft will be on the night-side of the comet (with the spacecraft still fully illuminated the Sun). In October Rosetta will transfer to a close mapping phase to observe the comet from a distance of 10 km. The spacecraft will move even closer to dispatch lander Philae to the surface in November. In this animation the comet is an artist’s impression and is not to scale with the spacecraft. The comet rotation is not representative (67P rotates once per 12.4 hours). Dates may be subject to change.
- Video 2 min Animation showing Rosetta’s orbit in the lead up to, during and after lander separation. The animation begins on 1 October 2014, when Rosetta is orbiting about 19 km from Comet 67P/Churyumov–Gerasimenko (all distances refer to the comet’s centre). The animation shows the transition to the close 10 km orbit by mid-October, and then the steps taken to move onto the pre-separation trajectory. On the day of landing, 12 November, Rosetta makes a further manoeuvre 2–3 hours before separation to move to 22.5 km from the comet centre to deploy the lander, Philae. While Philae descends to the surface over a period of seven hours, Rosetta makes another manoeuvre to maintain visibility with the lander. A series of 'relay phase' manoeuvres then move Rosetta out to a distance of about 50 km, before moving first to a 30 km orbit and later to an orbit at about 20 km by early December. The speed of the animation slows during the separation and lander phase to better highlight these events. The comet shape and rate of rotation is real – the comet rotates with a period of about 12.4 hours.