Frequently Asked Questions
Common
I am facing issue when trying to download the data by clicking on files. What can be done?
This is usually observed when you are using high latency network. You might try using chrome browser or integrate a download manager with your existing browser.
Also note that if you do not use the website for 30 minutes, it times out. In such a scenario, first login to PRADAN and then resume your download. You may try the 'Bulk Download' feature, instead.
Also note that if you do not use the website for 30 minutes, it times out. In such a scenario, first login to PRADAN and then resume your download. You may try the 'Bulk Download' feature, instead.
I am facing issue when trying to download the data by clicking on Download button. What can be done?
Please take a look at the message displayed above the table, it will guide you appropriately. You may also click on individual files to download the data.
The downloaded zip file does not contain all the files that I selected.
There is a limit defined on the number of file selection based on their sizes. This is also indicated in the warning message which is displayed when trying to download more than the defined limit. You may use the 'Select' feature provided below the data table to help you select the data.
When downloading data, how do I select data to ensure zip volume limits imposed by the application?
You may use the Select feature provided at the end of the payload pages to specify the serial number of the first row that you want to select, then specify the volume of data that is to be selected and then click select. This selects rows continuosly starting from the specified row, and shows you the last selected row in the table. This helps you to know the first row for your next selection.
If you want to select files manually, please use the file size column to know the individual file size and download button displays the limit imposed, to appropriately select the data.
If you want to select files manually, please use the file size column to know the individual file size and download button displays the limit imposed, to appropriately select the data.
After registration and email verification, it shows "Either the page does not exist or you do not have access to this page". How can I get access?
This means that the data access permission is to be assigned to you by the administrator. Please use the 'Contacts' page to reach the administrator.
RAMBHA
What is a Langmuir Probe?
A Langmuir probe consists of a metallic conductor (spherical/planar/cylindrical) electrically biased with respect to a reference electrode to collect electron and/or positive ions from the ambient medium and generates currents.
What parameters can be measured with LP?
LP is used to measure plasma density and electron temperature.
How to derive plasma parameters from LP data?
Using the current-voltage characteristics (after removal of photo emission current and ion saturation current: details given in user manual) of the Langmuir Probe, it is possible to determine the electron density and electron temperature. The slope of the retarding potential region of the V-log(I) curve is the reciprocal of Temperature in eV(electron Volt). From the electron temperature in Kelvin, the thermal velocity (Vth) is determined. Using the current J collected by the probe at the space potential Vs, the electron density is determined using the relation J = 0.25 Ne e A Vth, where e is electronic charge, A is the area of the probe and Ne is electron density.
How many days of operation of LP are to be undertaken on Moon?
LP was operated continuously from 24-08-2023 to 03-09-2023 for 11 days on the Moon.
What is the minimum threshold and saturation current of the LP?
The LP is designed to sense current in the range of 25pA to 25 μA.
At what height from the lunar surface, the plasma parameters are measured by RAMBHA-LP?
The plasma parameters are measured at a distance of ~2m from the surface.
What is the probe size and boom length of RLP? What material are those made of?
The probe is a metallic sphere of 5 cm diameter and the boom length is 1m. The probe is made from Ti Alloy and coated with TiN. The boom is fabricated with Carbon Fibre Reinforced Plastic(CFRP) material.
ChaSTE
What is ChaSTE?
ChaSTE stands for Chandra’s Surface Thermophysical Experiment. ChaSTE is a payload onboard Chandrayaan-3 Lander.
What parameters can be measured with ChaSTE?
ChaSTE could measure temperatures up to a depth of 10cms from the lunar surface regolith, at 10 different levels of depth.
How to derive temperatures from ChaSTE data?
The steps and required information are given in the Calibration document.
How many days of operation of ChaSTE has undertaken on Moon?
ChaSTE has operated on moon for 10 Earth days.
Which sensors are used for the temperature measurements?
Platinum Resistance Temperature Detectors (Pt-1000 RTD's) are used for temperature measurements.
At what depths the temperatures are measured?
From the lunar surface to ~ 10 cm temperatures are measured.
How often the measurements are made?
Temperature measurements are done for every second.
How was ChaSTE inserted in the lunar surface?
ChaSTE is a thermal probe consisting of temperature sensors spaced at different distances, which was inserted into the lunar regolith in a controlled manner based on telecommands (2.5 mm per commands) from the Earth station.
How thermal conductivity measurements were done in ChaSTE?
The measurement of change in temperature observed during ChaSTE active heating experiment (switching on the heater wounded at ninth sensor) is used to obtain absolute thermal conductivity of lunar regolith.
What is the material of the probe?
ChaSTE probe material is a low thermal conductivity composite (cyanate ester).
ILSA
What are seismic signals?
Seismic signals are ground vibrations generated by seismic activities. These are recorded by instruments called seismometers. They are of various types – long period, short period and broad band. These instruments provide the recorded data as ground acceleration, velocity or displacement.
What are the sources of seismic signals?
There are different sources of seismic signals which are natural or artificial in origin. This could be quakes, volcanoes, impacts, thermal energy release etc.
Are there ‘quakes’ in bodies other than Earth?
Yes, there are. Scientists have deployed instruments and recorded quakes on Moon, Mars etc. The seismometers of the Apollo landers in Moon and InSight in Mars have provided very valuable input to seismologists.
What is ILSA?
ILSA, Instrument for Lunar Seismic Activity is a strong motion short period type seismometer, a science instrument in lander of Chandrayaan 3. It was deployed on lunar surface and was operational during the entire mission period.
What is the technology behind the working of ILSA?
ILSA has a spring-mass structure that deflects in response to force coupled to it due to ground acceleration. The signal transduction is by capacitive technique. The sensor is fabricated using silicon micromachining technology called Micro Electro Mechanical Systems (MEMS).
What type of signals are recorded by ILSA?
ILSA has recorded several events on Moon of which majority are from known sources such as movement of rover and operation of other payloads. Certain events of unknown origin are also present in the data generated by ILSA.
LIBS
What is LIBS technique?
The ‘Laser Induced Breakdown Spectroscopy (LIBS)’ is one of the OES (optical emission spectroscopy) techniques, in which a high-irradiance laser beam ablates the sample surface and produces an intense plasma plume. The optical emission from the plasma plume is spectrally resolved to investigate the elemental composition of the target sample.
How to use Data Sets for analysis?
Refer documents titled, 'LIBS for Chandrayaan-3 Rover - Data User Manual' and 'LIBS DPSIS for Chandrayaan-3 Rover'.
What is element identification methodology?
The element identification methodology is based on the standard approach coined as 'Search and Assign' with respect to the standard atomic spectral database resources (NIST, Kurucz, etc,; https://physics.nits.gov/asd (ver_5.11) and http://kurucz.harvard.edu/linelist.html). In the first-attempt, the elemental identification can be with respect to the NIST database of persistent and strong atomic spectral lines of elements.
APXS
How to identify the elements present from the APXS spectra?
Energies of fluorescence lines of each element are different. By examining the spectrum, peak energies of the lines can be found and by comparing them against the atomic line lists, elements present can be identified.
How to obtain elemental abundances from APXS spectra?
By fitting the spectral lines, line intensities of various elements can be obtained and from these, abundances can be estimated using the line intensity-abundance correlations. More details are given in the user guide and the publication on ground calibration of APXS.
For measuring line intensities from the spectra, what are the methods?
The spectrum in the energy range of interest needs to be fitted with Gaussian lines and continuum. One possibility is to use XSPEC, an X-ray spectral fitting package as the APXS spectra and response files are compatible with this software. Otherwise, users may read the FITS spectral files in Python or any other programming language of choice and do the fitting.
Will the solar X-ray induced fluorescence signal (as used by Chandrayaan-2 CLASS) be significant contribution to the APXS observed X-ray spectra?
As the APXS observes a very small area (10 cm diameter), appreciable signal due to solar X-ray induced X-ray fluorescence will be there only when large (X-class) solar flares occur. There were no such flares during the APXS observation period and thus the contribution from XRF due to solar X-rays is negligible compared the XRF and PIXE induced by Cm-244 sources in the APXS instrument.
LI
How can I extract the information of product?
For each level of product there is corresponding XML label file. We can deduce basic information like datatype, no. of lines and no. of samples.
How to open the data products?
As the calibrated data products are provided in standard jpg format along with label file and it can be opened with any image viewer to load the jpg file.
What are the contents of downloaded zip?
When we unzip the zip file, we see three folders data,document and calibration. Based on the type of data products, the data folder contains directory/folders i.e. calibrated. For more information kindly refer to file naming convention of ch3 lim dp archive and sis document.
When we unzip the zip file we see the date folder under data folder what does it signify?
The date folder signifies the imaging date when the product is acquired. Morever the date and time of acquisition can be deduce from product file. For e.g. ch3_lim_nc1_20230823T1309510000_d_img_d18_1_001 product id signifies that product was acquired on 23 Aug. 2023 at 13:09:51.0000 UTC.
How to use the data products?
Kindly refer to ch3 lim dp archive and sis document.
Where to find ch3 lim dp archive and sis document?
Browse to Other Downloads and go to lim. Download lim.zip and unzip it. ch3 lim dp archive and sis document resides in document directory.
RI
How can I extract the information of product?
For each level of product there is corresponding XML label file. We can deduce basic information like datatype, no. of lines and no. of samples.
How to open the data products?
As the calibrated data products are provided in standard jpg format along with label file and it can be opened with any image viewer to load the jpg file.
What are the contents of downloaded zip?
When we unzip the zip file, we see three folders data,document and calibration. Based on the type of data products, the data folder contains directory/folders i.e. calibrated. For more information kindly refer to file naming convention of ch3 rim dp archive and sis document.
When we unzip the zip file we see the date folder under data folder what does it signify?
The date folder signifies the imaging date when the product is acquired. Morever the date and time of acquisition can be deduce from product file. For e.g. ch3_rim_nc1_20230902T0205270000_d_img_gnh_2_0 product id signifies that product was acquired on 02 Sep. 2023 at 02:05:27.0000 UTC.
How to use the data products?
Kindly refer to ch3 rim dp archive and sis document.
Where to find ch3 rim dp archive and sis document?
Browse to Other Downloads and go to rim. Download rim.zip and unzip it. ch3 rim dp archive and sis document resides in document directory.
NavCam
How can I extract the information of product?
For each level of product there is corresponding XML label file. We can deduce basic information like datatype, no. of lines and no. of samples.
How to open the data products?
As the raw and calibrated data products are provided in standard png format along with label file and it can be opened with any image viewer to load the png file.
What are the contents of downloaded zip?
When we unzip the zip file, we see three folders data,document and calibration. Based on the type of data products, the data folder contains directory/folders i.e. raw and calibrated. For more information kindly refer to file naming convention of ch3 nav dp archive and sis document.
When we unzip the zip file we see the date folder under data folder what does it signify?
The date folder signifies the imaging date when the product is acquired. Morever the date and time of acquisition can be deduce from product file. For e.g. ch3_nav_ncr_20230824T1415420000_d_img_d32_002 product id signifies that product was acquired on 24 Aug. 2023 at 14:15:42.0000 UTC.
How to use the data products?
Kindly refer to ch3 nav dp archive and sis document.
Where to find ch3 nav dp archive and sis document?
Browse to Other Downloads and go to nav. Download nav.zip and unzip it. ch3 nav dp archive and sis document resides in document directory.
SPICE
What are the Pre-requisites for using this dataset?
The user is expected to have a working knowledge of the SPICE Toolkit since all data in the dataset is in form of SPICE kernels.
How is the data organized for the propulsion and lander modules of Chandrayaan-3?
The dataset contains spice kernels for the ephemeris and attitude information of the propulsion and lander modules. The filenames of all kernels of propulsion module are prefixed by c3p and filenames of all kernels of lander module are prefixed by c3l. The coverage of each kernel is mentioned in the respective filename of the kernel and also in the associated xml label of the kernel.