Posts Tagged ‘Mars Orbit Insertion’

MOM successfully enters Mars orbit – first time ever on a maiden Mars mission

September 24, 2014

In what appears to have been a remarkably flawless and precise operation ISRO’s MOM has entered Mars orbit. It is the first time that a country has succeeded to get a spacecraft to enter Martian orbit on its maiden attempt.

“We have the signal.

1099 m/s.

Expected – 1098.7 m/s”

(The Mars Orbit Insertion burn had a planned duration of 24 minutes and 14 seconds, slowing the spacecraft down by 1,098.7 meters per second to be captured in an elliptical orbit around Mars.)

The operations took place while the spacecraft was behind Mars. It seemed an endless wait for it to reappear. It was then a seemingly endless 12.5 minutes from when telemetry was reactivated and the signals were received confirming that the maneuvers had been successful.

The precise orbit achieved now awaits further tracking information.

Foto

Prime Minister Narendra Modi arrived at ISRO in time to witness the critical and historical phases of the orbit insertion procedures (and he is to be highly commended for preferring real things to the meaningless, pointless and futile climate change talkshop at the UN).

He was more than a little pleased.

Narendra Modi at ISRO after MOM achieved orbit — screen grab by The Hindu

A major step not just for India’s confidence in its technological capabilities but also for its geopolitical positioning against China.

BBC: If all goes well and the satellite orbits the Red Planet, India’s space agency will become the fourth in the world after those of the United States, Russia and Europe to undertake a successful Mars mission. …..

…… After India’s successful unmanned Chandrayaan mission to the Moon in 2008 that brought back the first clinching evidence of the presence of water there, the Mars mission, according to K Radhakrishnan, chairman of the Indian Space Research Organisation (Isro), is a “natural progression”. …….

India sees the Mars mission as an opportunity to beat its regional rival China in reaching the planet, especially after a Russian mission carrying the first Chinese satellite to Mars failed in November 2011. Japan also failed in a similar effort in 1998.

China has beaten India in space in almost every aspect so far: it has rockets that can lift four times more weight than India’s, and in 2003, successfully launched its first human space flight which India has not yet embarked on. China launched its maiden mission to the Moon in 2007, ahead of India.

So if India’s mission succeeds, it will have something to feel proud about.

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Culmination nears for India’s Mars Orbiter Mission

September 23, 2014

In 8 hours – if everything goes as planned – the MOM would have been inserted into Mars orbit of 423 km at periareion and 80,000 Kilometers at apoareion  at an inclination of 150 degrees and with an orbital period of a little more than three days. Though a number of experiments are planned, the most important objectives of the mission – to demonstrate technology and capability – will largely have been accomplished on getting into orbit.

Frugal engineering and with a cost of about 10% of that of NASA’s MAVEN will have taken ISRO’s MOM into Mars orbit – and at the first attempt.

But the next few hours will be tense and nervous not only for ISRO mission staff but for the many millions of Indians who will be following the live webcast at http://webcast.isro.gov.in/. The critical operations will take place while the MOM spacecraft is occluded on the far side of Mars and when signals will be taking over 12 minutes to reach earth.

Spaceflight101: 

The critical Mars Orbit Insertion Burn Sequence will begin three hours ahead of the planned maneuver time when the spacecraft automatically switches over to its Medium Gain Antenna for communications since the High Gain Antenna will be pointing away from Earth during the retrograde burn.
21 minutes ahead of ignition, the spacecraft will begin the re-orientation to the proper attitude for the burn, pointing LAM to the direction of travel. The re-orientation is accomplished using the vehicle’s Reaction Wheels. Five minutes and 13 seconds ahead of the burn, the spacecraft passes into darkness – for the first time since leaving Earth last year. In advance, MOM will fully charge its battery to be in a safe configuration for the eclipse.
Three minutes ahead of the burn, the vehicle’s eight 22-Newton thrusters are enabled to start providing attitude control which they will continue to do throughout the main engine burn, keeping MOM pointing forward. Ignition of the Liquid Apogee Motor is planned at 1:47:32 UTC on Wednesday, September 24, 7:17 Indian Standard Time. The Mars Orbit Insertion burn has a planned duration of 24 minutes and 14 seconds, slowing the spacecraft down by 1,098.7 meters per second to be captured in an elliptical orbit around Mars. During the burn, the engines will consume 249.5 Kilograms of propellant leaving only about 40 Kilograms of propellant for the rest of the mission.
Should something go wrong during the burn, MOM is programmed to react appropriately in order to achieve a stable orbit around Mars – even if that means to spend all the vehicle’s propellant to do so. In the event the Liquid Apogee Motor is not ignited or its burn is cut short, MOM would automatically switch to the 22-Newton thrusters to supply as much delta-v as possible. Due to their lower thrust, the 22N thrusters would need to fire much longer than LAM along a greater stretch around the periapsis pass which will increase propellant consumption and leave MOM in a higher orbit.
MOI timeline

Graphic ISRO (via spaceflight101)

MOM test fires liquid motor for orbit insertion on Wednesday

September 22, 2014

A sigh of relief today as the liquid fueled motor was successfully test fired for 4 seconds after having last been used 9 months ago.

The 440 Newton Liquid Apogee Motor (LAM) of India’s Mars Orbiter Spacecraft, last fired on December 01, 2013, was successfully fired for a duration of 3.968 seconds at 1430 hrs IST today (September 22, 2014). This operation of the spacecraft’s main liquid engine was also used for the spacecraft’s trajectory correction and changed its velocity by 2.18 metre/second. With this successful test firing, Mars Orbiter Insertion (MOI) operation of the spacecraft is scheduled to be performed on the morning of September 24, 2014 at 07:17:32 hrs IST by firing the LAM along with eight smaller liquid engines for a duration of about 24 minutes.

The MOM is now in (or just entering) Mars’ sphere of influence and is effectively falling freely towards Mars. The orbit insertion procedure is described here.

Mars Orbit Insertion for MAVEN and MOM

graphic: indiaspaceactivity

On 24th 0127 GMT, even as it is falling with speed of 4 kms/sec, the craft is reoriented so that the thrusters face forward  ( for the next orbit maneuver of retro thrust to reduce the speed and to direct it in the required orbit ). The re-orientation is completed @ 0147 GMT. MOM would by this time be falling with a speed of  4.48Km/sec.

After the disturbances due to reorientation have died, i.e. 5 seconds later,  the Retro action starts with the firing of  LAM using 8 thrusters ..  the fall speed by now is 4.68 km/s. Even as the thrusters start their effort to reduce the speed of MOM, the fallingspeed continues to increase due to the gathered momentum upto 5.89 km/s and thenspeed  starts falling. The LAM firing also directs the craft in the desired direction so that it achieves the required orbit around Mars. The LAM operation ends @0216GMT.

As shown in figure there the MOM speed would increase from 3.18 Kms/sec to 5.89Kms/sec @  0216GMT.

Now notice that MOM approached Mars parellel to  equator unlike MAVEN which approached over North pole.  The reason for these two approaches is that the final orbits of MAVEN and MOM are inclined @ 75 deg and @ 19 deg respectively. This is evident from the ‘ cross roads ‘ seen between MOM and MAVEN release in the combination diagram shown above.

In the above flow of sequence we did not have time to  mention a couple of more chilling facts: @ nearly the same time when LAM operation starts MOM would go behind Mars as seen from Earth. Secondly , even if it was visible, whatever happens at MOM will be known to Earth only after 12 minutes due to the distance between Earth and MOM. So all this (and next described operations ) are being done under the unsupervised pre-loaded command sequences. So the success indicates how well are we in anticipating the situation through modelling.

A detailed look at dynamics of acceleration during this critical operation is shown in this graphic. (numbers are in kms/sec/sec ) corrosponding to sky blue curve. (X axis is time axis from 0110GMT to 0310GMT of 24 Sep. )
Violet curve is the speed normalized to fit in this graph with that of acceleration. Actual speed variation shown corresponds to 3.88 km/sec at left to 5.89km/s at peak near center which falls to 4 km/s at lsft edge.

We have also marked the events of reorientation (between red dots) and retro rocket firing (between Green dots ) on acceleration curve.

Notice that the LAM retro action started at first green dot on left ( 0152 GMT ) ..  it has tried to reduce the speed but the fall is more powerful, so MOM speed continues to increase despite retro action. This continues and for sometime eventhough the acceleration has started reducing ( blue line coming down ), the gathered momentum  makes the craft to increase its speed for sometime. Finally however the thrusters succeed in reducing the speed ( reversal near center of violet line ) ..  the thrusters are also turned off at that moment.(green dot near the center of graph ). Now the total operation of MOI is over.

Incidentally, the point where speed reversal has taken space forms the lowest point near the surface of MOM prior to first perigee which would occur after the craft completes one revolution.

Maven to enter Mars orbit tonight and MOM on Wednesday

September 21, 2014

UPDATE:

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft successfully entered Mars’ orbit at 10:24 p.m. EDT Sunday, Sept. 21, where it now will prepare to study the Red Planet’s upper atmosphere as never done before. MAVEN is the first spacecraft dedicated to exploring the tenuous upper atmosphere of Mars.

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NASA’s Maven will be inserted into Mars orbit later tonight at 2130 pm Eastern time and will be covered live by NASA TV.

India’s MOM should be inserted into Mars Orbit on Wednesday.

(Related: Alternate paths to Mars: NASA’s MAVEN compared to India’s MOM)

Maven planned Mars orbit insertion 20140921 - NASA

Maven planned Mars orbit insertion 20140921 – NASA

The orbit insertion factsheet from NASA is here: MAVEN Orbit Insertion Fact Sheet – NASA

The orbit-insertion maneuver will begin with the brief firing of six small thruster engines to steady the spacecraft. The engines will ignite and burn for 33 minutes to slow the craft, allowing it to be pulled into an elliptical orbit with a period of 35 hours.

Following orbit insertion, MAVEN will begin a six-week commissioning phase that includes maneuvering the spacecraft into its final orbit and testing its instruments and science-mapping commands. Thereafter, MAVEN will begin its one-Earth-year primary mission to take measurements of the composition, structure and escape of gases in Mars’ upper atmosphere and its interaction with the sun and solar wind….

MAVEN launched Nov. 18, 2013, from Cape Canaveral Air Force Station in Florida, carrying three instrument packages. It is the first spacecraft dedicated to exploring the upper atmosphere of Mars. The mission’s goal is to determine how the loss of atmospheric gas to space played a role in changing the Martian climate through time.

ISRO’s press briefing for the MOM Mars orbit insertion is here: MOM press briefing on Mars Orbit Insertion

MOM Mars Orbit insertion planned for 20140924  ISRO

MOM Mars Orbit insertion planned for 20140924 ISRO


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