Posts Tagged ‘Hohmann Transfer Orbit’

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

November 16, 2013

Update! 18th November 2013. The launch of MAVEN – in about 1 hour from now – can be seen live on NASA TV.

The Indian Mars Orbiter Mission is primarily a test of technology and capability and self-confidence and self-belief.

With a very limited budget.

The scientific investigations of the planet and the Martian atmosphere are only a secondary or even a tertiary objective. For the Indian mission everything is virtually for the first time. For NASA and the US, the MAVEN mission which is due to launch on Monday 18th November is the 15th Mission to Mars. The first mission (Mariner 3) failed and the second mission, Mariner 4, launched in November 1964 was the first to reach Mars. In the 49 years since there have been a few failures (Mariner 8 in 1971, Mars Observer 1992, Mars Climate Orbiter in 1998 and the Mars Polar lander/Deep Space2 in 1999) and some spectacular successes for NASA with the Mars Global Surveyor in 1996 , the Phoenix Mars Lander in 2007 and the Mars Rover in 2011.

Many Mars missions have failed. Between 1960 and 1971 the Russians (USSR) failed in 11 attempts to send a spacecraft to the vicinity of Mars. The 12th attempt with M-71 in 1971 succeeded in orbiting Mars. Of eight further attempts by Russia, 4 failed to reach Mars. The Japanese Nozomi failed while cruising. Two European missions led to one orbiter (but a failed landing) and one flyby.

On the surface they may both seem to be similar in that both are attempting to get a spacecraft into orbit around Mars. But the missions are, in reality, quite different. MOM is essentially a first-time test of technology and capability whereas MAVEN is primarily a scientific mission utilising the deployment of now well proven US technology. Technology development on the one hand and a scientific investigation on the other.

1. NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) is a space probe designed to study the Martian atmosphere while orbiting MarsIndia’s Mars Orbiter Mission (MOM – “Mangalyaan”) is a space probe designed to explore Mars’ surface features, morphology, mineralogy and Martian atmosphere using indigenous scientific instruments while orbiting Mars.

2. MAVEN is expected to have a budget of about $672 million. MOM has a budget of about $70 million.

3. The Atlas 5 rocket to be used to launch MAVEN has the capability to lift about 7,000 kg directly into a Geostationary transfer orbit (GTO). This allows MAVEN (2500 kg) to be injected directly into a Trans-Mars trajectory from launch.

The PSLV to be used for MOM can lift about 1300 kg into a GTO. With the MOM having a mass of 1337 kg, it becomes necessary for a  launch first into earth orbit and then a multi-step transition  through ever increasing earth orbits and finally into a Trans-Mars trajectory.

4. MAVEN is due to launch on an Atlas 5 rocket at 1:28 p.m. EST (1828 GMT) on Monday (Nov. 18) from Florida’s Cape Canaveral Air Force Station. Within one hour of launch MAVEN will be in a Hohmann Transfer Orbit with periapsis at Earth’s orbit and apoapsis at the distance of the orbit of Mars. MAVEN should reach Mars orbit on 22nd September 2014.

MAVEN trajectory - NASA-LASP-JPL

MAVEN trajectory – NASA-LASP-JPL

Because of the relatively low payload capability of the PSLV for an interplanetary mission MOM will spend more than four weeks in earth orbit and has to be equipped with radiation shielding to endure the numerous passages through earth’s radiation Belts. MOM has fired its Liquid Motor six times – always when passing perigee to gradually increase the apogee of the orbit to work its way up to departing Earth orbit in a fuel-efficient manner. The sixth (including one correction) firing yesterday placed the spacecraft in a 600 by approx 193,000 kilometer orbit around Earth and sets up the proper perigee passage for the final engine burn that puts the vehicle onto its Trans-Martian Trajectory using s standard Hohmann Transfer Orbit on 30th November/ 1st December. MOM should reach Mars orbit on 24th September 2014 (2 days after MAVEN).

mangalyaan trajectory

mangalyaan trajectory

5. MAVEN’s body has a cubical shape of about 2.3 m x 2.3 m x 2 m high, spans a total of 11.4 m with its solar panels deployed and has a lift-off mass of  2,454 kg (including fuel) and has a dry payload of 903 kg.

Mangalyaan’s body is a cuboid measuring about 1.5 m per side, a span of 4.2 m with solar panels deployed and an initial mass of 1337 kg of which 852 kg is fuel.



6. MAVEN is carrying 8 main, highly sophisticated instruments. Neutral Gas and Ion Mass SpectrometerImaging Ultraviolet SpectrographMagnetometerSolar Wind Electron AnalyzerSupraThermal And Thermal Ion CompositionLangmuir Probe and Waves antennaSolar Energetic ParticlesSolar Wind Ion Analyzer

Mangalyaan is carrying a camera, two spectrometers, a radiometer and a photometer. Together, they have a weight of about 15 kg.

7. MAVEN is targeting a science orbit of 150 by 6,200 Kilometers at an inclination of 75 degrees. It will perform measurements from a highly elliptical orbit around Mars over a period of one Earth year, with five “deep dips” at 150 km minimum altitude to sample the upper atmosphere.

Mangalyaan will be much further out and targets an operational orbit of 365 by 80,000 Kilometers with an inclination of 150 degrees and a duration of 76.72 hours from where it will perform its science mission. The MOM mission in Mars orbit is open-ended and is expected to last about 160 days.

8. MAVEN’s science phase features regular communication sessions. The spacecraft points its High Gain Antenna at Earth for high data rate communications twice per week with the exact timing depending on Deep Space Network visibility. Those comm sessions take place on Tuesday and Friday and have a duration of eight hours during which at least five hours of Earth pointing are required to downlink all science data and housekeeping telemetry. 

Mangalyaan is equipped with a 2.2-meter diameter High Gain Antenna which is a parabolic X-Band reflector antenna that is used for data downlink and command uplink. Science data and spacecraft telemetry is stored in two 16Gb Solid State Recorders aboard the vehicle for downlink during regular communications sessions. Low and Medium Gain Antennas are used for low-bandwidth communications such as command uplink and systems telemetry downlink.

As missions go, MAVEN represents a Mercedes “S” class to the Volkswagen that is MOM.

Mangalyaan - MOM (ISRO)

Mangalyaan – MOM (ISRO)



India’s frugal Mars orbiter mission completes 3rd burn in earth orbit

November 9, 2013

There has been some criticism  (within and outside India) from the usual suspects about the frugally-engineered, Indian, Mangalyaan Mars Orbiter mission as “being too expensive” for a developing country like India. I tend to discount these voices which merely continue the long, retrograde and shameful tradition of the Luddites. Some of these voices are of those who would like humankind to return to the trees. Others are of those who feel threatened by the idea of “backward nations” moving into space.

Reaching Mars is not that easy. More missions have failed than have succeeded. The full list of Mars missions is here. There are many crucial steps left for the Mangalyaan mission to achieve and success is far from assured.

TOI: India’s Mars Rover Mission (MOM) named ‘Mangalyaan’ is the 42nd mission aimed at understanding Mars. Out of the 41 missions so far, 25 have been declared failures and only 16 have been a success. Even the latest Phobos-Grunt/Yinghuo-1 launched by Russia/China was a failure as it got stranded in the earth’s orbit. 

Close on the heels of ‘Mangalyaan’ being sent into space by India, the United States (US) is also gearing up for the MAVEN mission to be launched on November 18, 2013. The mission is intended to be a step towards ‘unravelling the planetary puzzle about Mars’. The US is also gearing up for the Mars Rover 2020 mission to understand ‘Martian atmosphere’.

Underlying all missions is the vision of Mars one day being inhabited by humans. And that vision transcends the petty and mean criticism of those who can only see a “glass half empty”.

Last night the 3rd of five rocket burns was completed to lift the earth orbit of Mangalyaan from 40,186 km to 71,636 km (apogee). The fourth and fifth burns are planned for November 11th and 16th to raise the apogee to 100,000 km and then to 192,000 km. The 6th burn will be to leave Earth’s orbit and  insert the spacecraft into a trajectory towards Mars. The Trans-Mars injection is expected around 12.42 AM on December 1st.

ISRO: The third orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 02:10:43 hrs(IST) on Nov 09, 2013, with a burn time of 707 seconds has been successfully completed. The observed change in Apogee is from 40186km to 71636km.

ISRO’s Mission Profile.

The Launch Vehicle – PSLV-C25 will inject the Spacecraft into an Elliptical Parking Orbit with a perigee of 250 km and an apogee of 23,500 km. With six Liquid Engine firing, the spacecraft is gradually maneuvered into a hyperbolic trajectory with which it escapes from the Earth’s Sphere of Influence (SOI) and arrives at the Mars Sphere of Influence. When spacecraft reaches nearest point of Mars (Peri-apsis), it is maneuvered in to an elliptical orbit around Mars by firing the Liquid Engine. The spacecraft then moves around the Mars in an orbit with Peri-apsis of 366 km and Apo-apsis of about 80000 km. 

The mission consists of following three phases:

1. Geo Centric Phase
The spacecraft is injected into an Elliptic Parking Orbit by the launcher. With six main engine burns, the spacecraft is gradually maneuvered into a departure hyperbolic trajectory with which it escapes from the Earth’s Sphere of Influence (SOI) with Earth’s orbital velocity + V boost. The SOI of earth ends at 918347 km from the surface of the earth beyond which the perturbing force on the orbiter is mainly due to the Sun. One primary concern is how to get the spacecraft to Mars, on the least amount of fuel. ISRO uses a method of travel called a Hohmann Transfer Orbit – or a Minimum Energy Transfer Orbit – to send a spacecraft from Earth to Mars with the least amount of fuel possible. 

2. Helio Centric Phase
The spacecraft leaves Earth in a direction tangential to Earth’s orbit and encounters Mars tangentially to its orbit. The flight path is roughly one half of an ellipse around sun. Eventually it will intersect the orbit of Mars at the exact moment when Mars is there too. This trajectory becomes possible with certain allowances when the relative position of Earth, Mars and Sun form an angle of approximately 44o. Such an arrangement recur periodically at intervals of about 780 days. Minimum energy opportunities for Earth-Mars occur in November 2013, January 2016, May 2018 etc. 

3. Martian Phase
The spacecraft arrives at the Mars Sphere of Influence (around 573473 km from the surface of Mars) in a hyperbolic trajectory. At the time the spacecraft reaches the closest approach to Mars (Periapsis), it is captured into planned orbit around mars by imparting ∆V retro which is called the Mars Orbit Insertion (MOI) manoeuvre. The Earth-Mars trajectory is shown in the above figure. ISRO plans to launch the Mars Orbiter Mission during the November 2013 window utilizing minimum energy transfer opportunity.

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