And we thought the mission of India's Chandrayaan 3 was over; at least I
did. Turns out India's space agency,
ISRO, had a surprise for us Monday.
In a surprise announcement made Monday, ISRO announced that it has successfully returned the propulsion module used by the spacecraft into a high orbit around Earth. This experimental phase of the mission, the agency said in a statement, tested key capabilities needed for future lunar missions, including the potential for returning lunar rocks to Earth.
The primary mission of the probe the ISRO refers to as CH-3 was to carry their Vikram lander and Pragyan rover to the moon for their first lunar landing. That major goal was achieved on August 23rd, and while there were hopes the pair would survive the two week long lunar night, the mission was intended to last one lunar day and did.
After the landing, the propulsion module portion of Chandra (CH-3 PM) moved to an orbit
around the Moon at an altitude of 150 km. There it would carry out a mission
called SHAPE a remote sensing mission to observe Earth with a separate, dedicated instrument package.
Here's where things departed from the early plans. After a month of flying in this orbit, Indian mission operators found that the spacecraft still had a reserve of more than 100 kg of propellant, out of the original nearly 1700 kg of fuel and oxidizer.
The engineers knew that the SHAPE mission could carry out its observations of Earth's atmosphere from a different orbit. By looking at Earth from a distance, this innovative science experiment seeks to set a benchmark for what to expect from the atmospheric signatures of exoplanets that may be capable of supporting life. So, the Indian engineers reasoned, it would be good to demonstrate the capability of their spacecraft to return to Earth orbit.
"It was decided to use the available fuel in the PM to derive additional information for future lunar missions and demonstrate the mission operation strategies for a sample return mission," the Indian space agency said Monday.
On October 9, CH-3 PM raised its lunar orbit from 150 km to 5,112 km, and four
days later it burned its engine again to begin exiting lunar orbit and
transitioning into Earth orbit. It reached its perigee on November 22,
at an altitude of 154,000 km (95,700 miles). That's far beyond the
geostationary orbit at 22,236 miles, over four times the distance from the
surface, and not likely to threaten any operational satellites around
Earth. It's also an orbit from which the SHAPE payload can observe our
atmosphere.
CH-3 PM's path from lunar orbit (greenish color) to Earth orbit (yellow). From ISRO
Ars Technica's Eric Berger takes this as a demonstration that India has replaced Russia as the third most advanced deep-space exploration program in the world, bumping Russia down to #4.
India placed a spacecraft into orbit around Mars in 2014, and its Vikram
lander succeeded in December after Russia's Luna 25 spacecraft crashed into the Moon in August. I see his point of view.
Good on India. That's a very interesting add-on/surprise they sprung on us.
ReplyDeleteAgain, non-traditional legacy aerospace is lapped by TheNewGuysOnTheBlock. Even though India is government-sponsored, they still meet the requirements of TNGOTB.
And they're pushing quickly on their very own manned space program that isn't a direct copy of Soviet/Russian stuff (like the ChiCom stuff is, from their capsule to their space station modules.)
Doesn't having that much fuel left indicate someone made a serious error at some point? They paid to ship all that extra fuel all the way to the moon... Or could it be this was all part of the plan but the plan is only being revealed in stages as they have successes?
ReplyDeleteIt's different to have all that extra mass, than to have solar cells and batteries that outlast the official mission. How much does it cost in initial fuel to get an excess ton and a half to the moon?
n
This is just a WAG, but I'd guess it might have been some worst case margin that wasn't needed. Remember, this is like 5.9% of the fuel leftover (100/1700), so my guess is they budgeted for some worst case amount consumed and it didn't turn out to be worst case. Which is virtually always what happens.
Deleteperhaps the extra fuel / mass was included to allow for options on lunar orbit. having failed previously, ISRO may have added redundancy / extra fuel to allow for options if everything not perfect on arrival?
ReplyDeleteYeah, I think you're exactly right.
DeleteInteresting that over a ton is less than 6%, and that it's enough to reverse the trip when you don't have the earth's gravity well to escape...
ReplyDeletenick
Bu it's not a ton, it's 100 kg. A ton is 1000 kg.
DeleteA Metric Ton is 1000kg, which is English 2200 lbs.
DeleteNot that anybody worth their salt uses English measurements any more when it comes to the Sciences.
Except the people that have actually landed on the Moon.
DeleteSorry, must have misread it as I thought it was 1700 kg of leftover fuel. Seemed like a lot which was my point. If it's just a couple of hundred pounds that makes more sense.
Deletenick
Point of Order:
ReplyDeleteWing-Flapping over acronyming an American probe after a space cartoon, but not a peep at India naming a series of probes after the doctor that created HAL 9000?
My HARUMPH! radar is twitching.
Nice catch - the name seemed familiar but didn't catch it.
Delete