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Phobos-Grunt - Mission Design and Timeline
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Launch and Interplanetary Insertion
Phobos Grunt will launch in a 20-day launch window, beginning on November 5, 2011. The Spacecraft will be carried into its initial orbit by a Zenit-2SB Rocket lifting off from Site 45 at the Baikonur Cosmodrome, Kazakhstan. Launch is planned for November 8, 2011 at 3:16pm EST.
After nominal ascent by the two-stage Zenit Rocket, the Payload and its propulsion module will be in a parking orbit of 207 by 347 Kilometers with an inclination of 51.4 degrees. The Spacecraft’s engines will make the first Burn at around two and a half hours into the mission to make the orbit highly elliptical. This 10-minute Burn of the Engine will put Phobos-Grunt into a 250 by 4,150 to 4,170Km Orbit. Another coast phase begins and the Propulsion System performs the jettisoning of spent propellant tanks. Just short of 6 Hours into the mission, the crucial Burn that puts the spacecraft into its interplanetary trajectory starts. This Engine Burn will have a duration of 17 minutes and 20 seconds. After that, Phobos Grunt will be on its way to Mars.
After nominal ascent by the two-stage Zenit Rocket, the Payload and its propulsion module will be in a parking orbit of 207 by 347 Kilometers with an inclination of 51.4 degrees. The Spacecraft’s engines will make the first Burn at around two and a half hours into the mission to make the orbit highly elliptical. This 10-minute Burn of the Engine will put Phobos-Grunt into a 250 by 4,150 to 4,170Km Orbit. Another coast phase begins and the Propulsion System performs the jettisoning of spent propellant tanks. Just short of 6 Hours into the mission, the crucial Burn that puts the spacecraft into its interplanetary trajectory starts. This Engine Burn will have a duration of 17 minutes and 20 seconds. After that, Phobos Grunt will be on its way to Mars.
Ground Track from Launch to Interplanetary Insertion
Source: Roscosmos
These Burns will be performed out of range of Russian Ground Control Network Stations. Roscosmos has asked astronomers in South America to observe the Burns and submit data that they collect. These visual observations will help in case of a failure during one of these engine firings.
Ground Track - Orbit Adjust Burn
Source: Roscosmos
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Ground Track - Interplanetary Insertion Burn
Source: Roscosmos
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Thin Red Line: Track in Daylight; Thick Red Line: Burn in Daylight; Thin Black Line: Track in Darkness; Thick Black Line: Burn in Darkness
Ascent Timeline
| Date | Time (GMT) | T+ | Event | Orbit | |
| Nov 8, 2011 | 20:16:03 | 00:00:00 | Launch | ||
| Nov 8, 2011 | 20:27:27 | 00:11:24 | Spacecraft Separation | 207x347Km | |
| Nov 8, 2011 | 22:55:47 | 02:39:44 | MDU Ignition 1 | ||
| Nov 8, 2011 | 23:05:18 | 02:49:15 | MDU Shutdown 1 | 250x4,150-4,170Km | |
| Nov 8, 2011 | 23:07:17 | 02:51:14 | Tanks Separation | ||
| Nov 9, 2011 | 01:02:48 | 04:46:45 | MDU Ignition 2 | ||
| Nov 9, 2011 | 01:20:09 | 05:04:06 | MDU Shutdown 2 | Interplanetary Trajectory |
Cruise to Mars
After being inserted into its interplanetary trajectory, the spacecraft undergoes extensive checkouts and calibrations. Also planned for this cruise phase are three large trajectory correction maneuvers: The first takes place 5 to 10 days after launch and provides a change in velocity of 85m/s, the second burn takes place 65 days after launch for a velocity change of 10m/s, the third burn sets up for the Orbital Insertion Burn at Mars and is performed around a month prior to Mars Arrival (dV:35m/s).
The Cruise Phase will have a duration of ~11 Months and set the stage for a Mars Arrival in October 2012.
The Cruise Phase will have a duration of ~11 Months and set the stage for a Mars Arrival in October 2012.
Orbit Operations, Rendezvous, Phobos Landing, Landed Operations
To insert itself into Martian Orbit, Phobos-Grunt uses its Propulsion Module once again to slow down and get captured in a 800 by 80,000Km Orbit. For that it has to decelerate by 800m/s. Once in orbit, the Propulsion Module will separate along with the lower truss segment. The Chinese Mars Orbiter ‘Yinghuo-1’ is released shortly thereafter and begins its operational mission in Martion Orbit at that time. While in orbit, the spacecraft will study Mars and Atmospheric Properties
The most critical part prior to landing on Phobos is the Rendezvous with the Moon. This process will take about 9 Months and require several orbit correction maneuvers. When the orbit of the Spacecraft matches the one of Phobos after several weeks of approaching and tracking the moon at a distance of ~150km, the landing Phase begins. Landing is set to occur in February of 2013. Onboard sensors will provide navigation data and the vehicle will close in on the surface to a point of about 12Km when final approach begins. The Descent will be almost vertical and take less than one hour. Laser Ranging will become ineffective at low altitude levels and the spacecraft will switch to Radar Navigation. Attitude Control Thrusters provide three axis stabilization. The Landing will be performed at a very low velocity as the small Moon has a fairly weak gravitational field so that the vehicle actually has to be pushed against the surface when making contact. Landing Legs will provide a signal at the time of touchdown and attitude control jets will fire to complete the landing process.
Once the lander is down, Images will be acquired for scientists on Earth to select soil targets in the vicinity of the lander. Soil Samples will be delivered to the return system by a robotic arm that can reach samples as far as 1 meter from the lander. The sample acquisition Phase of the mission will have a duration of 2 days to one week. When all samples are on board, the Return Vehicle separates from the Lander and ‘Launches’ from Phobos. Because of the small gravitational forces, springs will push the vehicle away from Phobos to avoid contamination of the lander. On Phobos, science operations would begin immediately after the departure of the return spacecraft. Mass Spectrometry and visual examinations of soil will be performed. In-Situ Science Operations will continue for one year before the mission comes to an end. Due to power limitations, the scienctific instruments on the lander will be turned on and off on a schedule that is developed by scientists on Earth. Scientists hope to answer questions on the Formation of the Martian Moons after analyzing Phobos' soil.
Should a failure in the communication system occur, the spacecraft has a built-in sequencer that enables it to perform sample acquisition autonomously and send the return vehicle back to Earth automatically.
The most critical part prior to landing on Phobos is the Rendezvous with the Moon. This process will take about 9 Months and require several orbit correction maneuvers. When the orbit of the Spacecraft matches the one of Phobos after several weeks of approaching and tracking the moon at a distance of ~150km, the landing Phase begins. Landing is set to occur in February of 2013. Onboard sensors will provide navigation data and the vehicle will close in on the surface to a point of about 12Km when final approach begins. The Descent will be almost vertical and take less than one hour. Laser Ranging will become ineffective at low altitude levels and the spacecraft will switch to Radar Navigation. Attitude Control Thrusters provide three axis stabilization. The Landing will be performed at a very low velocity as the small Moon has a fairly weak gravitational field so that the vehicle actually has to be pushed against the surface when making contact. Landing Legs will provide a signal at the time of touchdown and attitude control jets will fire to complete the landing process.
Once the lander is down, Images will be acquired for scientists on Earth to select soil targets in the vicinity of the lander. Soil Samples will be delivered to the return system by a robotic arm that can reach samples as far as 1 meter from the lander. The sample acquisition Phase of the mission will have a duration of 2 days to one week. When all samples are on board, the Return Vehicle separates from the Lander and ‘Launches’ from Phobos. Because of the small gravitational forces, springs will push the vehicle away from Phobos to avoid contamination of the lander. On Phobos, science operations would begin immediately after the departure of the return spacecraft. Mass Spectrometry and visual examinations of soil will be performed. In-Situ Science Operations will continue for one year before the mission comes to an end. Due to power limitations, the scienctific instruments on the lander will be turned on and off on a schedule that is developed by scientists on Earth. Scientists hope to answer questions on the Formation of the Martian Moons after analyzing Phobos' soil.
Should a failure in the communication system occur, the spacecraft has a built-in sequencer that enables it to perform sample acquisition autonomously and send the return vehicle back to Earth automatically.
Mission Design Illustration
Credit: Lavochkin Association
Sample Return and Landing
The Return Vehicle will drift away from Phobos to a distance of 10 Kilometers before igniting its engine to increase its velocity by 20m/s. After that burn, the spacecraft is in an initial Orbit around Mars which will be made highly elliptical by a second engine burn. Several weeks of cruising in Martian Orbit will follow to wait for the appropriate time to begin the return trip. A third maneuver puts the vehicle into its trajectory toward Earth. After 11 months, the Return Vehicle separated from the Entry Capsule that hits the atmosphere at a speed of 11.8m/s. The vehicle will be tracked visually and by using radar as there are no navigational electronics or beacons aboard the small capsule containing the samples and the LIFE Experiment, that is planned to land in Kazakhstan near the Sary Shagan test range that has radar equipment in order to pinpoint the exact landing site. A successful retrieval of samples from Phobos will set the stage for years of analysis.
Mission Timeline
| Date | Event | |
| Nov 8, 2011 | Launch | |
| Nov 8, 2011 | Orbital Insertion | |
| Nov 8, 2011 | Interplanetary Insertion | |
| Oct 12, 2012 | Mars Orbit Insertion | |
| Feb 14, 2013 | Landing on Phobos | |
| Feb 18, 2013 | Liftoff from Phobos | |
| Aug ?? 2014 | Landing on Earth |
