Tech demonstration mission has to demonstrate they can use, power and operate scientific instruments successfully, get data and process them.
These links might help
...an experimental ion engine (they do have one in the works IIRC)...
... why did they include something like a Mars Colour Camera, instead of an experimental ion engine (in addition to the LAM)? The scientific community already has a million images of Mars... taken from much closer than Mangalyaan's nominal peri-areion. They've got full-disk images too - and if AIUI, all this data is already in the public domain. Sure, more images always helps; but the tradeoff is having a system which enhances the chances of mission success, while validating a new indigenous implementation of an alternative propulsion technology.
In that sense, an experimental ion engine (they do have one in the works IIRC) would be as good, if not a better (as I said in my previous comment) 'payload'.
Quote from: Mader Levap on 09/13/2014 10:36 amTech demonstration mission has to demonstrate they can use, power and operate scientific instruments successfully, get data and process them.They've already demonstrated a lot of that in the numerous Earth observation missions they've undertaken.
1) ISRO engineers will start the final orbit insertion operation at 4.17 am on September 24 morning when the Mars Orbiter will switch to the Medium Gain Antenna for communications. 2) At 6.56 am, the Orbiter will be rotated in a forward direction.3) At 7.12, a solar eclipse starts and two minutes later the thrusters will be used to get the Orbiter aimed in the right attitude. 4) At 7.17 am, the liquid engine burn will start and it will go on for 1454 seconds burning 249.5 kg of propellant to decelerate the spacecraft by 1098.7 Meters/second. 5) Around the same time, telemetry machines would be switched off as the Orbiter will lose communications with ground control being on the other side of the planet. 6) News of the confirmation that burn has started will reach ground control only after 12.5 minutes at 7.30 am.7) The communication gap will end at 7.45 am and telemetry and doppler tracking will resume at 7.47 if all goes according to plan.
In the run-up to the D-day, the mission scientists will do course (trajectory) correction on September 22. “The course correction has been postponed to September 22 from Sunday (September 14) to conserve the precious liquid fuel weighing (852 kg) and ensure the orbital insertion takes place when the spacecraft is closer to Mars for smooth transition from the sun’s orbit,” Mr. Rao said.
“The liquid apogee motor (LAM) or fuel engine at the bottom of the spacecraft will be fired on September 22 for four seconds to enter the Martian sphere of influence and the course correction will consume about 500gm of fuel,” Mr. Rao said.
The speed of the spacecraft will also be reduced to 2.14 metre per second from 22.2 km per second for enabling smooth transition into the Martian orbit from the sun’s orbit Sep 24.
At 6.56 a.m., the spacecraft will be rotated towards Mars and five minutes later when sunlight is not falling on the Martian surface causing eclipse, the thrusters beneath the engine will give the Orbiter altitude control.“The liquid engine will start firing at 7.17 a.m. and at 7.21 a.m., Mars occult begins. A minute later at 7.22 a.m., telemetry (radio signals) will be off or out of receiving radars on the earth,” Mr. Rao pointed out.Scientists at the space agency’s deep space network at Byalalu, about 40 km from Bangalore, NASA’s Earth station at Goldstone on the U.S. west coast, the ESA’s Earth station at Madrid will confirm the insertion into the Martian orbit 24 minutes later at 7.54 a.m.
The spacecraft, with five scientific instruments, will be placed in an elliptical orbit, with the nearest distance from the Martian surface being 423 km and the furthest 80,000 km, to rotate around it in a duration equivalent to 3.2 earth days.
According to the press briefing, the delta-V is 1098.7 m/s.
As per the propulsion diagram ( Page:8 ) in the press briefing document, both the LAM and the attitude thrusters use the same propellant and oxidizer. How come there is so much concern about the restarting and operation performance of LAM, but no apparent concerns on the thrusters operation?
How come there is so much concern about the restarting and operation performance of LAM, but no apparent concerns on the thrusters operation?
Quote from: seshagirib on 09/16/2014 09:51 amHow come there is so much concern about the restarting and operation performance of LAM, but no apparent concerns on the thrusters operation?My guess: The smaller thrusters are designed to operate for many years, and have done so on previous missions. They have also been used for the TCMs during the flight. The LAM was originally designed for a few firings immediately after launch, and doesn't have the same kind of record for long term use.That said, the fact ISRO decided to do a test firing so late in the process might indicate some more specific concerns were identified post launch. If it were a NASA mission, I would expect a test like this to be planned out before launch, unless it was driven by issues identified later. That logic might not apply to MOM though, given that it's ISRO's first deep space mission and was developed on such a tight schedule.
BANGALORE: Prime Minister Narendra Modi has expressed interest in witnessing the entry of Mars Orbiter Mission into the red planet around 7.30 am on September 24.Modi would arrive in Karnataka on September 23 on his maiden visit, after taking over the country’s top job.The Prime Minister is likely to visit ISRO Telemetry, Tracking and Command Network (ISTRAC) near Peenya here to witness the historic event and congratulate the ISRO team. The BJP state leadership has planned a grand reception for Modi on his arrival at the HAL airport in the evening. Former Deputy Chief Minister R Ashok and others inspected the airport on Tuesday to select a suitable spot for erecting a shamiana for the purpose.BJP state president Prahlad Joshi, Union Minister H N Ananth Kumar and others would felicitate Modi, Subbanna of the BJP Bangalore city unit told Express.Modi would stay at Raj Bhavan for the night and leave for Tumkur the next morning. He is keen on visiting ISTRAC before leaving for Tumkur.