Mort Walker wrote:From Nair's interview it appears there will be real-time pictures during the descent and landing. But would it be broadcast to the world soon?
In less than 13 hours, the Chandrayaan-2 mission's lander Vikram is going to enter the most challenging phase of its journey as it attempts to soft land near the Moon's hitherto unexplored south pole. In fact, the Indian Space Research Organisation (ISRO) has described it as "15 minutes of terror". According to the space agency, the lander hopes to touch down in a high plain between two craters, Manzinus C and Simpelius N.
The 1,471 kg lander successfully separated from the orbiter on Monday and began revolving around the Moon, lowering its orbit over two manoeuvres and performing several pre-landing tests.
According to ISRO Chairman K. Sivan, the final descent is going to be terrifying as the agency has not done it before. "It is for the first time we are going to another body where there is no atmosphere and using the propulsion system we will have to break the velocity and bring the vehicle safely to soft land. To achieve this we will have to balance between the gravity and thrust. So we have to modulate the thrust of the engine," he said.
Moreover, of the 38 attempts of 'soft landing' on the lunar surface so far, only 20 have been successful. Just five months back, Israel's attempt crash-landed on the moon. If things go to plan on Saturday morning, India will become the fourth country after Russia, the US and China to achieve success.
So what will happen in the last 15 minutes before touchdown?
At 1:40 am on September 7, Vikram will begin its descent from a height of 35 km above the lunar surface and a velocity of around 6,000 kmph. In just over 10 minutes, the lander will drop to a height of 7.4 km above the Moon altitude and lower its speed to around 526 kmph.
At this point things will pick up pace and every second will matter. Over the next 38 seconds, the lander will further reduce its speed to 331.2 kmph and reach a height of 5 km above the lunar surface. As it drops to an altitude to 400 metres above the lunar surface in the course of the following 1.5 minutes, Vikram will have to lose more velocity and reach a speed of approximately 100 kmph. At this point it will briefly suspend its descent and hover for about 12 seconds to collect data of the lunar surface.
Touchdown is less than three minutes away at this point. When Vikram resumes its descent, it will drop 300 mts in the span of 66 seconds and once again hover at the height of 100 mts above the lunar surface. This pause of about 25 seconds is to give the lander a chance to make a final choice between two pre-determined landing sites. The onboard instruments will give it the necessary data to make this decision - the lander carries three scientific payloads to conduct surface and subsurface science experiments.
If Vikram chooses the first site, the lander will make a vertical descent to a height of 10 mts above the lunar surface over 65 seconds while significantly reducing its velocity. On the other hand, if it opts for the second site, it will first descend to a height of 60 mts over 40 seconds, and then drop down to 10 metres in the next 25 seconds. Either way, from the height of 10 mts, Vikram will take just 13 seconds to hopefully make history and soft land on the moon. Fifteen minutes after the touchdown, Vikram will send in the first pictures. Keep in mind, that the data mentioned above are approximations and reality may not match the plan on paper.
The primary objective of the fully indigenous Chandrayaan-2 mission is to demonstrate the ability to operate a robotic rover on the lunar surface. So four hours after landing, between 5.30 am and 6.30 am, the Pragyaan rover will be unloaded from the Vikram lander. The six-wheeled robotic vehicle with a mass of 27 kg will then carry out surface and sub-surface experiments for one lunar day, which is equal to around 14 Earth days. It can travel at a speed of 1 cm per second and leverages solar energy for its functioning. It will cover 500 metres in its lifetime.
Apart from studying the presence of water on the Moon, Chandrayaan-2 will also perform experiments that will hopefully shed light on the origins of the Solar System and, by extension, life.
What kind of soil is expected around the lunar South Pole? Loose sandy type? Given the frigid temperatures and possibility of water can the surface be icy?
"We are eagerly waiting for the event. Everything is going according to the plan," Isro chairman K Sivan said. The touch-down of 'Vikram' lander is scheduled between 1.30 am and 2.30 am on Saturday, followed by the rollout of rover 'Pragyan' between 5.30 a.m and 6.30 a.m. "Certainly there is lot of anxiety in the minds of the entire (Chandrayaan-2) team because it's a very complex operation and we are doing it for the first time," a senior official associated with the mission, said on condition of anonymity. "Everything... sensors, computers, command systems... has to work perfectly. But we are confident in the sense we have conducted a large number of simulations on the ground; it gives us the confidence it would go alright," the official said. He described the soft-landing as "almost like placing a baby on the cradle", and said, "there is certain amount of anxiety but there is no fear."
Supratik wrote:Is this operation going to be shown live on any Indian TV channels?
Arjun wrote:What kind of soil is expected around the lunar South Pole? Loose sandy type? Given the frigid temperatures and possibility of water can the surface be icy?
: The landing ellipse is generally flat in the LRO WAC DTM (‘GLD100’ at 100 m/pixel) and is confined by craters of varying diameter. The center of the landing ellipse (i.e., PLS) is devoid of craters with significant depth. The estimated age of the landing ellipse reveals that it is younger than the age of impact craters present to the north (e.g. Manzinus)`. Ejecta of the crater Schomberger in the south superimpose the landing ellipse region. Therefore, it is possible that these craters could have significantly changed the stratigraphy of the landing region. The 1:5,000,000lunar geologic renovation (2013) map I-703 shows that the geologic unit within the landing ellipse corresponds to unit Ntp (Nectarian plains) [15-16]. Ntp is defined as ‘terra mantling and plains material’ and is proposed to be sourced by primary and secondary ejecta deposits
of Nectarian basins and large craters on the Moon [15].
Therefore, it is likely that the landing ellipse may host
primary crustal materials.
Our spectral analysis suggests the presence of weak
absorption bands centered at ~900-950 nm and ~2000
nm at two locations within the landing ellipse. This
indicates the presence of low-calcium pyroxene. The
landing ellipse is mainly dominated by highland-type
featureless spectra indicative of FAN lithologies. Our
spectral and chemical composition analyses suggest
that the surface composition corresponds to FAN materials mixed with Mg-suite rocks. We hypothesize that
such a lithology could be a result of mixing of ejecta
from the SPA basin impact that may have excavated
and redistributed lower crustal or upper mantle materials.
Ityadi ityadi ..
Mort Walker wrote:Arnab Goswami will be covering it live on Republic TV and I’m sure he’ll find someone to shout at. Regardless of failure or success, that will still be fun to watch.
SwamyG wrote:Mort Walker wrote:Arnab Goswami will be covering it live on Republic TV and I’m sure he’ll find someone to shout at. Regardless of failure or success, that will still be fun to watch.
OT: I heard the rumor that both Vikram and Pragyan can hear Arnab. So that communication channel is definitely open.
Timeline in UTC:
20:08 "Rough" braking burn (30 km altitude)
20:18 "Fine" braking burn (7.4 km altitude)
20:20 Start of terminal guidance navigation
20:22 First picture from descent camera
20:23 Touchdown
22:23 Deployment of rover ramp
22:53 Rover power up
23:33 Rover solar panel deployment
23:49 Start of rover roll off
23:59 Rover roll down onto lunar surface
00:15 Rover takes picture of lander
Amber G. wrote:Read all about it, for example here:
GEOLOGICAL INSIGHTS INTO CHANDRAYAAN-2 LANDING SITE IN THE SOUTHERN HIGH LATITUDES OF THE MOON.
You have detailed description of soil/minerals etc around the area:: The landing ellipse is generally flat in the LRO WAC DTM (‘GLD100’ at 100 m/pixel) and is confined by craters of varying diameter. The center of the landing ellipse (i.e., PLS) is devoid of craters with significant depth. The estimated age of the landing ellipse reveals that it is younger than the age of impact craters present to the north (e.g. Manzinus)`. Ejecta of the crater Schomberger in the south superimpose the landing ellipse region. Therefore, it is possible that these craters could have significantly changed the stratigraphy of the landing region. The 1:5,000,000lunar geologic renovation (2013) map I-703 shows that the geologic unit within the landing ellipse corresponds to unit Ntp (Nectarian plains) [15-16]. Ntp is defined as ‘terra mantling and plains material’ and is proposed to be sourced by primary and secondary ejecta deposits
of Nectarian basins and large craters on the Moon [15].
Therefore, it is likely that the landing ellipse may host
primary crustal materials.
Our spectral analysis suggests the presence of weak
absorption bands centered at ~900-950 nm and ~2000
nm at two locations within the landing ellipse. This
indicates the presence of low-calcium pyroxene. The
landing ellipse is mainly dominated by highland-type
featureless spectra indicative of FAN lithologies. Our
spectral and chemical composition analyses suggest
that the surface composition corresponds to FAN materials mixed with Mg-suite rocks. We hypothesize that
such a lithology could be a result of mixing of ejecta
from the SPA basin impact that may have excavated
and redistributed lower crustal or upper mantle materials.
Ityadi ityadi ..
Landing & Rover Deployment
Post midnight, Vikram will begin the 15-minute final descent between 1am and 2am. As per Isro’s plan, about 10 minutes later, it would have dropped to reach a height of 7.4km from the lunar surface.
In the next 38 seconds, it will reach a height of 5km and another 89 seconds later Vikram's altitude will be 400m.
At 400m, Vikram will hover for about 12 seconds to collect some data from the lunar surface and then further reduce its altitude in the next 66 seconds, to reach a height of 100m.
At this height (100m), Vikram will hover again to decide if it must land on the first preferred site or the second one. Its onboard
instruments will tell Vikram what to do.
If it can land on the first site, Vikram will, in 65 seconds, reach a height of 10m directly. In case it has to pick the second landing site, it will use 40 seconds to first descend to a height of 60m, then, further drop down to 10m in the next 25 seconds. From the height of 10m, it will take Vikram 13 seconds to touchdown on Moon.
sooraj wrote:Timeline in UTC:
20:08 "Rough" braking burn (30 km altitude)
20:18 "Fine" braking burn (7.4 km altitude)
20:20 Start of terminal guidance navigation
20:22 First picture from descent camera
20:23 Touchdown
22:23 Deployment of rover ramp
22:53 Rover power up
23:33 Rover solar panel deployment
23:49 Start of rover roll off
23:59 Rover roll down onto lunar surface
00:15 Rover takes picture of lander
22:17 (IST), Sep 06
Visuals from Isro Monitoring Centre in Bengaluru.
The final descent of #Chandrayaan2 to take place on the Lunar South Pole, tonight. #Visuals from ISRO Monitoring Ce… https://t.co/o2LYsRztRL
— ANI (@ANI) 1567787815000
21:53 (IST), Sep 06
PM Modi received by Karnataka CM BS Yeddiyurappa at Bengaluru Airport
PM Modi arrives at Bengaluru airport, to head to Isro monitoring centre
21:09 (IST), Sep 06
Jerry Michael Linengar, former Nasa astronaut is in India to do a special show at 11.30pm on Friday night on Chandrayaan-2 moon landing that will be live telecast on National Geographic.
21:08 (IST), Sep 06
Over 300 journalists from across the country, including some from the foreign media, have congregated at ISTRAC to cover the moon landing in the south pole.
.. Well done. Next orbit will be the last one for Vikram anyway.
Return to “Military Issues & History Forum”
Users browsing this forum: dwaipayandhar, Karan M and 56 guests
