# Tag Info

43

All interplanetary probes that I am aware of were launched into a parking orbit, and then waited some time in that orbit before restarting a stage or igniting another stage to inject on the desired outgoing asymptote. This is done for convenience to allow long launch windows on days in the launch period. It is possible and slightly more efficient to launch ...

24

As @Ame mentioned, the rocket didn't have enough fuel to put it there in one shot, like most US/Russian rockets do. However, the actual physics behind the orbital maneuver is slightly different than described. Specifically, the physics is called the Oberth effect. The short explanation of this is that a rocket thrust is more effective if done at perigee. ...

21

Comparing Mangalyaan (MOM) to Maven there's a significant difference in mission, scientific capabilities and operational lifetime. Maven's primary purpose is to study the martian atmosphere, whereas MOM is more of a general purpose probe with surface study instruments. Maven has over 4 times the payload (65kg vs 15kg) and nearly double the number of ...

21

There are several reasons why Satellites need to orbit Earth before they go interplanetary... The first reason: The launch site is very rarely in the right position to start an interplanetary flight. Earth rotates on a tilt, so a launch has to be timed when Kennedy Space Center crosses the ecliptic plane (the general plane that most planets orbit on). Also, ...

18

Sphere of influence The gravitational sphere of influence asks which of two gravitating bodies should be used as the origin for purposes of modeling the behavior of some third body such as a spacecraft. This comes into play in at least two key places: In a patched conic approximation, what's the right place to switch from one conic to another? When a ...

17

As per "From lighter rocket to slingshot, Isro innovates its way to Mars" from Hindustan Times: The main reasons for the low cost are: Low labour cost. In India scientists are working with very low pay which indirectly drives cost down. Scientists relied on technologies they had used before. India had their PSLV launches before. The hardware of Chandrayaan ...

14

In the case of India's PSLV, the launch vehicle is not powerful enough to insert the Mars Orbiter Mission probe directly on a route to Mars. In contrast MAVEN is to be launched using the much more powerful Atlas V. The probe has to use gravity assist to gain enough velocity to travel to Mars. I.e. the probe first goes into a highly elliptical orbit, and ...

13

ISRO calls these "Midnight Maneuvers". This question, why do these maneuvers fall at around midnight Indian Standard Time (IST), has been asked by some of their readers on Mars Orbiter Mission's Facebook page before, and ISRO answered: “Firing has to happen near the perigee and in the visibility from ISTRAC ground stations. All these orbits have ...

12

There are a couple of definitions, but the most useful one is called the Hill Sphere. Essentially this is the area around which one can orbit around an object, and not be pulled away by another object (Such as the Sun). As the linked article states, it can be calculated for objects that have one object much more massive than the other (Almost every case of ...

12

Their future plans does not have Mars as a target at the moment. The ISRO is working manned mission technology in addition to the Moon, Venus, Sun and asteroid probes. They are also working to collaborate more with NASA on Mars and Moon missions after their first successful NASA/ISRO success: “To this end the working group agreed to continue discussions ...

10

ISRO's MOM lifting off (credit ...

9

Other than taking images of Mars' moon Deimos far side (something not done in decades) not much has been attributed to MOM yet. The key here is to remember that the the orbiter likely won't discover anything per se, but the science data it produces can be used (probably in conjunction with other data) to help us understand the history of Mars. Here is an ...

8

Before you get to all other advantages, let's start with the single, essential one. A rocket floating in place (not flying up at all, just hovering over the launchpad) needs to generate enough thrust that would otherwise give it $9.8 m/s^2$ acceleration (1g) in horizontal flight. That's quite a bit, and that's all wasted thrust. If you launch directly up, ...

7

There are proposals for a follow-up mission to Mars, involving a lander: http://www.newindianexpress.com/states/kerala/VSSC-Chief-Hints-at-Second-Mars-Mission-Using-GSLV/2013/12/21/article1957410.ece This mission would be launched using either the GSLV-Mk2 or Mk3.

7

According to a follow-up question in the comments to this ISRO's announcement on Facebook: Rajesh B Nataraja: Basic question? The forward rotation is to alter the thrusters in the right direction for the sling shot? ISRO's Mars Orbiter Mission: You are absolutely right! So this maneuver was about positioning the spacecraft in the direction for the ...

6

This question is not actually related to space, except insofar as comms in space could be picked up from anywhere on Earth (as opposed to surface comms which may be limited to line of sight or short range) The real question to ask is: what type of comms do you need to protect, either through encryption to keep them private, or through authentication to ...

6

No. Some spaceflight records are authenticated by the FAI (Fédération Aéronautique Internationale) under its sub-body FAI Astronautic Records Commission but these are generally highest/longest/fastest type records involving human spaceflight. A famous controversy arose over Yuri Gagarin's flight because of FAI rules stating that the pilot had to land in ...

5

Download Eyes on the Solar System. Mars Orbiter Mission is one of the spacecraft tracked therein. It looks to be a little behind MAVEN, also tracked. The measuring tools can tell you how far away it is from anything else that's tracked, like the Sun, Earth, Mars, and MAVEN. Clicking on additional information button in its toolbar, it displays an external ...

5

According to the abstract Target Martian Orbit Selection for ISRO Mars Orbiter Mission, a number of constraints were taken into account: The other orbit parameters of Inclination, Right Ascension of Ascending Node and Argument of Perigee were selected after a detailed analysis to meet the following Mission constraints:- maximum eclipse period should be ...

5

I think they had an issue with the methane sensor. From India's Mars Orbiter Mission Has a Methane Problem: The problem has to do with how the instrument collects and processes detections of methane in the atmosphere, a technique known as spectroscopy. "Imagine that you hold your hand in front of you and extend your four fingers ... Suppose that ...

4

Communications blackout was because they phased orbits of Mars orbiters to be "behind Mars" when at greatest risk of cometary dust impacts. MOM phased its orbit too and so did NASA's / ESA's Mars orbiters. Depending on their orbit, this communications blackout should last roughly 40 minutes. With MOM's highly elliptical and over three Earth days long (nearly ...

4

The planet calculator lists a J2 of $0.001960454$ for Mars, higher than the Earth's $0.001082627$. That makes sense, as Mars has a smaller mass, but still approximately the same rotation rate. That means achieving a sun-synchronous around Mars is slightly easier than around Earth. However, MOM is not in such an orbit.

3

There are a couple of ways these can come. In the case of the image you provided, I believe they are using known altitude that comes from MOLA data which accurately found the elevation of the entire Martian surface, and using that to transform the image as it was. They are likely using some terrain features from the image to determine it's altitude as well. ...

3

[Update: This information has been superseded by more recent info, which challenges the operational value of the sensor data. See the other answer.] As of March 2015, the Mars Orbiter Mission (MOM) methane sensor has been working, but has not detected any methane. ISRO has released some data on the operations so far. Emily Lakdawalla explains: The map ...

3

This is what I use in class, these are standard formulas from any text book. Define 2 functions sphereOfInfluence[dominantMass_, minorMass_, distanceBetween_] := (minorMass/dominantMass)^(2/5)*distanceBetween sphereOfGravitation[dominantMass_, minorMass_, distanceBetween_] := (minorMass/dominantMass)^(1/2)*distanceBetween (*valid only for ...

3

Originally, MOM was going to use the GSLV to launch. The GSLV has about 50% more capacity than the PSLV. As a result, a few things had to be cut back from the mission, including the payload, removal of a direct to Mars orbit, among others.

2

According to Wikipedia, "At the end of the orbit insertion, MOM was left with 40 kg (88 lb) of fuel as against the 20 kg (44 lb) that was thought necessary for the six-month life span." (see https://en.m.wikipedia.org/wiki/Mars_Orbiter_Mission)

2

Dr. Kiran Kumar of ISRO, in his speech at IITG Ahmedabad has confirmed that the magnetic fields of the coils cancel each other when energized together. This was (fortunately) found in earth orbit, during the fourth orbit raising manoeuvre. http://www.youtube.com/watch?v=l_e7L0nJTQw#t=392 ( from 5:02 onwards ) I believe this confirms my original guess on ...

2

It's not clear that the thrusters are considered more reliable. It may be as simple as it being unlikely that both the LAM and the thrusters would fail, and the thrusters have quite a bit of redundancy if a subset fail. Depending on how they're arranged, four working thrusters might be enough to orient the craft for the MOI burn, and two could do the "Plan B"...

2

@Hohmannfan's answer states MOM is not in a sun-synchronous orbit. I just though I'd add some math to that. Using the equation for rotation of ascending node posted by @MarkAdler, I calculated the delta_OMEGA - how much the ascending node rotates in one year, for two cases: earth LEO and mars MOM. For earth LEO (400km) I get a little more than 97 degrees, ...

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