Aditya-L1 (आदित्य -L1): Launch and Discussions

Amber G. · Post by **Amber G.** » 01 Sep 2023 23:49

Starting a New Thread:

SSSalvi wrote: ↑01 Sep 2023 21:13 AdityaL1 Launch Kit doc is out!!!!

Now SRF should start new thread.

https://www.isro.gov.in/media_isro/pdf/ ... ochure.pdf

Amber G. · Post by **Amber G.** » 01 Sep 2023 23:53

Some general information about L1 point and orbits around it - Basic physics..
Way I explain is using rotating frame of reference -- dealing with fictions forces like centrifugal along with gravity -- makes math a little simpler

Lagrange points are specific locations in space where the gravitational forces of two large bodies, such as the Earth and the Sun, balance the centrifugal force felt by a smaller object. There are five Lagrange points in the Earth-Sun system: L1, L2, L3, L4, and L5.

The L1 Lagrange point lies on the line connecting the two large bodies, closer to the smaller body (in this case, Earth). At the L1 point, the gravitational pull from the Earth is balanced by the centrifugal force due to the combined gravity of the Earth and the Sun. This creates a point where an object can effectively "hover" relative to the Earth's position.

A halo orbit around the L1 point is a type of three-dimensional, unstable periodic orbit. It's called a "halo" orbit because if you were to view the path from a distance, it would resemble a ring or a halo around the L1 point. These orbits are highly complex and result from the gravitational interactions between the Earth, the Sun, and the spacecraft.

From a general physics standpoint, halo orbits are a fascinating result of the interplay between gravitational forces and centripetal (centrifugal) forces. Imagine a spacecraft situated at the L1 point. If it drifts slightly in any direction, the gravitational forces from the Earth and the Sun will attempt to pull it back to the equilibrium point at L1. However, due to the unstable nature of this equilibrium, the spacecraft can't remain exactly at L1 but instead traces a path around it.

Think of it like balancing a pencil on the tip of your finger – any slight displacement will cause the pencil to oscillate around the balanced position. Similarly, the spacecraft in a halo orbit experiences oscillations around the L1 point, creating a dynamic and complex trajectory.

The Aditya-L1 mission aims to study the Sun, its outermost layer (corona), and the solar wind. Placing a spacecraft in a halo orbit around the L1 point allows for a relatively stable position with an uninterrupted view of the Sun, as the spacecraft moves in sync with Earth's orbit around the Sun.

In summary -- halo orbits around the L1 Lagrange point are a result of gravitational and centrifugal forces acting in equilibrium, creating a dynamic yet relatively stable orbital path. This concept is crucial for missions like Aditya-L1, enabling prolonged and unobstructed observations of the Sun from this specific vantage point.

-----
Once Aditya is at (near) L1, it is *always* between sun and earth. (L1 is a point which remains fixed with respect to sun and earth in the reference system of rotating earth around the sun).

(Lagrange points in the Sun–Earth system (not to scale) – a small object at any one of the five points will hold its relative position).

Since L1 is not stable -- Both L1 and L2 points are unstable on a time scale of approximately 23 days, which requires satellites orbiting these positions to undergo regular course and attitude corrections --(Halo orbits)... but aditya-1 is never far away from line joining earth and real adtiya (sun).

(This is not to the scale, the actual planned orbit around L1 has a very small angular radius as seen from earth)

For more details see for example <this> or <this>

Najunamar · Post by **Najunamar** » 02 Sep 2023 00:18

AmberGJi,
Based on when the Aditya observer will reach the L1 point, Jan 2024, the sun’s South Pole will be slightly closer so from the South Pole of the Moon to South Pole of the Sun! We’re exploring for the Global “South”…

akashganga · Post by **akashganga** » 02 Sep 2023 04:26

Good information by a Profession - https://www.youtube.com/watch?v=jtVE0JeXd0g

asbchakri · Post by **asbchakri** » 02 Sep 2023 06:32

So does anyone know where it will be telecasted live

Ok found this

uddu · Post by **uddu** » 02 Sep 2023 08:57

Please promote ISRO's own channel

Amber G. · Post by **Amber G.** » 02 Sep 2023 10:51

Hoping Aditya L1 orbit data was made available to NASA/JPL and made public via Horizons.. Like CY3 we can have upto date orbits.

Amber G. · Post by **Amber G.** » 02 Sep 2023 11:16

Credit: (From updates on ESA’s support to Aditya-L1.)

Aditya-L1 will not travel to L1 directly from launch. Instead, ISRO operators will need to perform a ‘transfer manoeuvre...

This manoeuvre will be performed soon after launch, as the amount of fuel required to achieve the necessary trajectory grows quickly with time. Aditya-L1 will first perform manoeuvres to adjust its orbit around Earth after launch, before performing a transfer manoeuvre to L1. The spacecraft will reach L1 approximately 100 days after launch.

rahulm · Post by **rahulm** » 02 Sep 2023 11:40

Aditya L1 Launch LIVE Updates: It's on. ISRO sets timer for Sun mission

European Space Agency(ESA) is backing Saturday's mission. It is providing deep space communication services to the mission, and has helped with the new flight dynamics software.

With what new flight dynamics software has the ESA helped ISRO?

Pratyush · Post by **Pratyush** » 02 Sep 2023 12:02

Launch successful. Performance normal.

g.sarkar · Post by **g.sarkar** » 02 Sep 2023 12:14

Naar Maal! Congratulations ISRO. Where is Dilbuji at this critical time?
Gautam

nitzter · Post by **nitzter** » 02 Sep 2023 12:19

Altitude showed deviation. Range director announced PS4 burn sequences would change, right?!

Aarvee · Post by **Aarvee** » 02 Sep 2023 12:32

What's happening? Why this round table now?

nitzter · Post by **nitzter** » 02 Sep 2023 12:41

Signal re-acquired!

Aarvee · Post by **Aarvee** » 02 Sep 2023 12:41

nitzter wrote: ↑02 Sep 2023 12:41 Signal re-acquired!

Phew!

nitzter · Post by **nitzter** » 02 Sep 2023 12:47

We need more stations - ground or ship based. Dark periods are nail biting.

From altitude trajectory it appears as if the PS3 solid motor over performed. Although the feedback based burn was later managed by PS4...

Aarvee · Post by **Aarvee** » 02 Sep 2023 12:54

Congrats ISRO, satellite successfully inserted

nitzter · Post by **nitzter** » 02 Sep 2023 12:56

Injected into a very good orbit - 233x19470 (235x19500 desired).

SSridhar · Post by **SSridhar** » 02 Sep 2023 13:05

Excellent news. We now await Aditya reaching L1 Halo orbit on the S-E axis.

juvva · Post by **juvva** » 02 Sep 2023 13:09

phew !!!!! how i wish dd doesn't leave us in the dark on tenterhooks in the middle of a mission, the discussion could have waited...

that to on a day on which dilbu has taken day off.

SSridhar · Post by **SSridhar** » 02 Sep 2023 13:16

nitzter wrote: ↑02 Sep 2023 12:47 We need more stations - ground or ship based. Dark periods are nail biting.

Additionally, we should start building Tracking & Data Relay Satellites (TDRS). Already two TDRSs are being made to be in place to support Gaganyaan.

Cybaru · Post by **Cybaru** » 02 Sep 2023 13:46

Good stuff! Congratulations... Whats the next mission??

rahulm · Post by **rahulm** » 02 Sep 2023 13:55

Cybaru wrote: ↑02 Sep 2023 13:46 Good stuff! Congratulations... Whats the next mission??

Gaganyaan test - hopefully next month.

sanman · Post by **sanman** » 02 Sep 2023 15:18

rahulm wrote: ↑02 Sep 2023 13:55
Cybaru wrote: ↑02 Sep 2023 13:46 Good stuff! Congratulations... Whats the next mission??
Gaganyaan test - hopefully next month.

They're now saying early October (it's been delayed many times before)

This will be the in-flight abort test of the Gaganyaan crew capsule (first of 2 such test flights)
A booster rocket will launch the crew capsule into the sky, and they will separate that crew capsule from the rocket in mid-flight, to show that it can properly separate in the event that a malfunction with the launch vehicle requires the crew to be saved.

This test-flight will be called TV-D1 (Test Vehicle - Demonstration 1).
While the crew capsule and its escape system are being tested during this flight, the "test vehicle" mentioned in the title does not refer to the capsule itself - it refers to the rather ordinary-looking rocket that will carry the capsule into the sky.

This ordinary-looking rocket booster is being used for this test flight as a stand-in for our large LVM3, which the crew capsule will eventually fly on for the Gaganyaan mission. That way, we don't have to waste our larger & more expensive LVM3 rocket on a mere test flight.

But this same ordinary-looking rocket booster ("test vehicle") has also been made to later eventually be used for testing something else.
Can you all guess what that is?

nitzter · Post by **nitzter** » 02 Sep 2023 16:09

sanman wrote: ↑02 Sep 2023 15:18
But this same ordinary-looking rocket booster ("test vehicle") has also been made to later eventually be used for testing something else.
Can you all guess what that is?

Is it the RLV?

nitzter · Post by **nitzter** » 02 Sep 2023 16:14

juvva wrote: ↑02 Sep 2023 13:09 phew !!!!! how i wish dd doesn't leave us in the dark on tenterhooks in the middle of a mission, the discussion could have waited...

that to on a day on which dilbu has taken day off.

Hahaha...

I agree they should have at least flashed the latest updates at the footer of the screen. People unaware about communication breakoff phase were all going crazy in the live chat.

nitzter · Post by **nitzter** » 02 Sep 2023 16:20

SSridhar wrote: ↑02 Sep 2023 13:16
nitzter wrote: ↑02 Sep 2023 12:47 We need more stations - ground or ship based. Dark periods are nail biting.
Additionally, we should start building Tracking & Data Relay Satellites (TDRS). Already two TDRSs are being made to be in place to support Gaganyaan.

Any timeframe out for these two satellites?

sanman · Post by **sanman** » 02 Sep 2023 17:36

nitzter wrote: ↑02 Sep 2023 16:09
sanman wrote: ↑02 Sep 2023 15:18
But this same ordinary-looking rocket booster ("test vehicle") has also been made to later eventually be used for testing something else.
Can you all guess what that is?

Is it the RLV?

Yes, it's the RLV.

hanumadu · Post by **hanumadu** » 02 Sep 2023 18:25

ESA's validation support for Aditya L1's flight dynamics software.

https://www.esa.int/Enabling_Support/Op ... ar_mission

Looks like some kind of back box testing without looking into each other's code and also simulation data to test Aditya L1 software.

To get to L1 and safely stay in orbit, operators need to know exactly where their spacecraft was, is and will be. To do so, they apply mathematical formulas to the tracking data from the spacecraft to calculate its past, present and future location in a process known as ‘orbit determination’.

Orbit determination is carried out with the help of specially designed software. ISRO has designed and developed new orbit determination software for Aditya-L1. However, given the tiny margin for error that comes with operating a spacecraft at L1, they requested support from ESA to validate it.

....

First, the ESA team invented typical scenarios that the ISRO team could face when operating Aditya-L1. Both teams then used their own orbit determination software to predict how Aditya-L1’s orbit would evolve in these scenarios and compared their results.

The next step saw ESA provide ISRO with simulated tracking data similar to the data that ESA uses to train its own flight dynamics teams. This includes data typical of a spacecraft’s critical Launch and Early Orbit Phase, a complex orbit insertion manoeuvre or even a planetary flyby. The ISRO team used their software to analyse the data, and then both teams worked together to detect any areas that could be improved and fine-tune some of the algorithms.

Finally, the ESA team provided the ISRO team with tracking data from a real spacecraft orbiting L1. Both teams used their own software to analyse the data from ESA’s former LISA Pathfinder mission and compared their results once again.

The results of the exercise were valuable for ESA and ISRO and both teams are confident in the capabilities of ISRO’s software.

Dumal · Post by **Dumal** » 02 Sep 2023 19:18

Did anyone notice what looked like a sonic boom within seconds of liftoff. The vapour cone or what looked more like a ring was visible and I thought I heard some booms at the same time as well. If it was a sonic boom, is it common with these type of launches or was it anything special today due to the dry weather or something else?

Dilbu · Post by **Dilbu** » 02 Sep 2023 19:33

It was just another naarmal PSLV launch. No need for any anti-jinx.

Amber G. · Post by **Amber G.** » 02 Sep 2023 19:57

hanumadu wrote: ↑02 Sep 2023 18:25 ESA's validation support for Aditya L1's flight dynamics software.

https://www.esa.int/Enabling_Support/Op ... ar_mission

Thanks for posting this - Good article, recommend it to read.

ESA' is supporting Aditya L1 mission, and is a good source for updates and information..

Here is some excellent summarization and basic information: ( Source: ESA's tweets, ESA portal etc)

AdityaL1 is our first mission to a Lagrange point, and happy to see so much support and good wishes from all over.

Lagrange point 1 is a tricky place to fly spacecraft: Getting there requires a complex transfer manoeuvre, and staying there requires regular manoeuvres to maintain the halo orbit.

To carry out the precise manoeuvres needed to handle an L1 mission, operators need to know the exact location of their spacecraft, now and in the future.

They work this out through a mathematical process called ‘orbit determination’.

ISRO has developed new ‘orbit determination’ software for AdityaL1.
But the room for error when operating a spacecraft at L1 is very small.
So, the Aditya-L1 team worked with ESA to make sure the software could handle the challenges they may face during the mission.

ESA has experience flying and even rescuing missions at Lagrange points, so this experience is was a very good thing.

ESA's 'orbit determination' software was used ini Gaia and Euclid telescopes at L2. L2 is also home to the NASA/ESA/CSA James Webb Space Telescope.

From April to December 2022, the ESA & ISRO teams used ISRO's software to analyse simulated tracking data, and then real data from an ESA spacecraft at L1.

Together, the teams worked to identify areas that the software could be improved and to fine-tune its algorithms.

Both teams learned a lot and all are confident in the capabilities of ISRO’s new software.

ESA' is providing support for GroundStation and FlightDynamics support as mentioned in the above link,

Amber G. · Post by **Amber G.** » 02 Sep 2023 20:20

For aam but seriously interested janta , allow me to post some background, well known but sometimes not noted:

Following list is not complete or up-to-date , but it provides an overview of some missions that have operated near L1:

SOHO (Solar and Heliospheric Observatory): SOHO is a joint mission by NASA and the European Space Agency (ESA). It has been operational since 1995 and is stationed at the L1 point. Its primary mission is to study the Sun and its influence on the solar system.

STEREO (Solar Terrestrial Relations Observatory): STEREO is a pair of spacecraft launched by NASA in 2006. These spacecraft were designed to study the Sun and the solar wind, and they operate in orbits that allow them to observe the Sun from different perspectives, including L1.

Planck: Although Planck completed its mission in 2013, it was placed in a halo orbit around L1 to study the cosmic microwave background radiation. It was a mission of the European Space Agency (ESA).

JWST (James Webb Space Telescope): While not stationed at L1, JWST is positioned at the second Lagrangian point, L2, which is on the opposite side of Earth from the Sun. This space telescope is observing distant galaxies, stars, and planetary systems.

DSCOVR (Deep Space Climate Observatory): DSCOVR, launched in 2015, is stationed at L1 and is a joint mission by NASA, NOAA, and the U.S. Air Force. It primarily observes the Earth's climate and monitors space weather.

Various future missions have been proposed or planned to be stationed at or near L1 or other Lagrangian points for different purposes, including space observatories and Earth-monitoring missions.

(This is by no means a complete list - just some I was very interested in/was)

bala · Post by **bala** » 02 Sep 2023 20:25

Fantastic job ISRO! This coming on the success of Chandrayaan-3. ISRO's Nigar Shaji is the project director Aditya-L1. She praised U R Rao a former chairman of ISRO for the aditya mission. PSLV performed flawlessly. Huge Respect and admiration for the entire ISRO team and their dedication day and night for flawless execution of the mission. Proud of all the achievements and more to come. ISRO is indeed India's pride and the worlds too.

juvva · Post by **juvva** » 02 Sep 2023 20:30

looks like aditya will have quiet a few neighbours, should isro be wary of close encounters?

ramana · Post by **ramana** » 02 Sep 2023 22:29

Two links:

1) On India and China in Space: https://www.thespacereview.com/article/4245/1

2) List of objects at Lagrange Points!

https://en.wikipedia.org/wiki/List_of_o ... nge_points

ramana · Post by **ramana** » 02 Sep 2023 22:30

https://www.isro.gov.in/media_isro/pdf/ ... ochure.pdf
Very detailed description of the Aditya-L1 mission

Amber G. · Post by **Amber G.** » 03 Sep 2023 01:22

juvva wrote: ↑02 Sep 2023 20:30 looks like aditya will have quiet a few neighbours, should isro be wary of close encounters?

Though people call it a 'Lagrange "point" the halo (or Lissajous orbits) orbits are quite big. They are complex and are three dimensional orbits..
For Aditya (and others) sharing space is of the order of few hundred thousand kilometers in these three dimensions.
(If x direction is line joining earth and sun, y is perpendicular to this but in the same plane as ecliptic, and z is "up/down" (perpendicular to both) -- the box is about 200,000 Km in x direction, 600,000 Km in Y direction and about 100,000 Km in Z- direction) (Yes the "orbit" is quite complex!!!)

Plenty of space for all in the L1 neighborhood.

(Math is complex, and pictures are difficult to draw - but may be I will try to draw/explain those orbits, as most newspapers etc don't do justice)

sanjaykumar · Post by **sanjaykumar** » 03 Sep 2023 01:38

How delayed is the Aditya mission?

sudarshan · Post by **sudarshan** » 03 Sep 2023 01:49

It seems L1 is unstable, which means any perturbation from the exact L1 point results in a (fictitious) force which tends to accelerate the object away from the point. This seems like the opposite of being in orbit around an attractor - it's like being in orbit against a repeller (if you know what I mean). The other difference from being in orbit around a gravitational well seems to be that with a gravitational well, the attractive force increases as one gets closer. Whereas with the L1 point, the "repulsive force" would increase with distance. Is this the reason why the orbital dynamics around the L1 point are so complex?