Suramya's Blog : Welcome to my crazy life…

ISRO (Indian Space Research Organisation) has been quite active in the past few years and has been making significant progress in its mandate to power the next generation of Indian Space capabilities. On Sunday ISRO successfully completed the landing experiment of the Reusable Launch Vehicle-Technology Demonstration (RLV-TD) which is a key part of ISRO’s goal to create a reusable low cost two-stage orbital launch vehicle.

“The RLV took off at 7:10 a.m. by a Chinook helicopter of the IAF as an underslung load and flew at a height of 4.5 km. Once the predetermined pillbox parameters were attained, based on the RLV’s Mission Management and Computer command, the RLV has released mid-air, at a down range of 4.6 km,” ISRO said.

The autonomous landing was carried out under the exact conditions of a Space Re-entry vehicle’s landing —high speed, unmanned, precise landing from the same return path— as if the vehicle arrives from space. Landing parameters such as Ground relative velocity, the sink rate of Landing Gears, and precise body rates, as might be experienced by an orbital re-entry space vehicle in its return path, were achieved. The RLV LEX demanded several state-of-the-art technologies including accurate Navigation hardware and software, Pseudolite system, Ka-band Radar Altimeter, NavIC receiver, indigenous Landing Gear, Aerofoil honey-comb fins and brake parachute system.

In a first in the world, a winged body has been carried to an altitude of 4.5 km by a helicopter and released for carrying out an autonomous landing on a runway. RLV is essentially a space plane with a low lift to drag ratio requiring an approach at high glide angles that necessitated a landing at high velocities of 350 kmph. LEX utilized several indigenous systems. Localized Navigation systems based on pseudolite systems, instrumentation, and sensor systems, etc. were developed by ISRO. Digital Elevation Model (DEM) of the landing site with a Ka-band Radar Altimeter provided accurate altitude information. Extensive wind tunnel tests and CFD simulations enabled aerodynamic characterization of RLV prior to the flight. Adaptation of contemporary technologies developed for RLV LEX turns other operational launch vehicles of ISRO more cost-effective.

Keep in mind that this was a Technology Demonstration test, or what we call Proof of Concept (PoC) in Software Development. Now that we have successfully shown that the technology works as expected, they can start scaling it up, add more functionality/redundancy etc to productionalize it and make it ready for the live test a couple of years down the line.

Looking forward to more such positive news from ISRO going forward.

Source: ISRO successfully conducts the Reusable Launch Vehicle Autonomous Landing Mission

– Suramya

The Indian Space Program has been running on an accelerated schedule over the past few years. We had the Chandrayaan 2 launch in 2019 followed by multiple record breaking launch of 104 satellites (It was later broken by Space X, but efforts are ongoing to break their record of 143 satellites launched.

India is aiming to launch an Indian crewed orbital spacecraft Gaganyaan (“Space Craft”) by Q4, 2024. If all goes well India will become the 4th country to put a human in space after Russia, US and China. This is an extremely ambitious program that will push the Indian Space Research Organisation (ISRO) to its limits. This was announced yesterday by India’s Minister for Atomic Energy and Space, Dr Jitendra Singh in his answer to a question posed in the Lok Sabha.

(a) The first uncrewed flight of Gaganyaan programme i.e. ‘G1’ mission is aimed at validating the performance of Human rated launch vehicle, Orbital module propulsion system, mission management, communication system and recovery operations. The mission will carry a humanoid as payload. In view of the paramount importance of crew safety, two Test Vehicle missions are planned before the ‘G1’ mission to demonstrate the performance of crew escape system and parachute-based deceleration system for different flight conditions.

(b) Yes, Sir. The uncrewed ‘G1’ mission is targeted to be launched in the last quarter of 2023 followed by the second uncrewed ‘G2’ mission in the second quarter of 2024. India’s maiden human space flight ‘H1’ mission is targeted to be launched in the fourth quarter of 2024.

(c) & (d) Yes, Sir. The astronaut designates for human space flight mission are identified and are currently undergoing their mission specific training at Bengaluru. First semester of Astronaut training has been
completed wherein they have undergone course modules on Theoretical basics, Space medicine, Launch vehicles, spacecraft system and ground support infrastructure. Regular physical fitness sessions, aeromedical training and flying practice are also part of crew training. Corresponding evaluation and assessment activities have also been completed. The second semester of crew training is currently in progress.

Another interesting point for this launch is that the training for the astronauts is being conducted in India itself at ISRO’s facility in Bangalore instead of in Russia as it was done in the past. Now that the initial announcement has been made, we need to publicize this a lot more to get everyone excited about the launch. If possible I will def be planning a visit to Sriharikota to witness the launch in person.

I am looking forward to the launch and wish ISRO all the best. This is a proud moment for all Indians. Jai Hind.

Source: Gaganyaan: ISRO plans to launch first human space flight mission in 2024 & India schedules first crewed space mission for Q4, 2024

– Suramya

One of the problems with having Humans in space and living there is how to deal with cosmic radiation. When we start talking about having habitats in Space, for example on the Moon or on Mars, dangers of cosmic radiation is one of the risks that we have to address. We don’t have to worry about it in our daily life because on Earth we are protected by its magnetic shield from the cosmic radiation, however once we get outside the atmosphere & magnetic shield it becomes an issue. Unprotected humans living on the Space Station are at significant risk for radiation sickness, increased risk of cancer and degenerative diseases. Dangers of Cosmic radiation are long known however there has never been any accurate measurement of how much stronger the Cosmic radiation is on the Moon since it doesn’t have an atmosphere or magnetic field to block the dangerous radiation and knowing the strength of the radiation would be crucial in designing habitats on the Moon to protect the astronauts living there.

Now thanks to an International collaborative effort we finally have an answer to the question “How much higher is the Radiation on the moon, as compared to Earth & the ISS”. Using the Lunar Lander Neutron and Dosimetry (LND) which was part of the payload on China’s Chang’e-4 lunar probe (which landed on the far side of the moon early last year) the researchers were able to measure the radiation it was exposed to. Basically the LND measured the total amount of radiation it was exposed to over the 2 week period of its operation and sent that data back to earth where the researchers divided the total radiation dose by the amount of time tool operated to calculate the daily total.

This gives us the first concrete measurement of the Cosmic radiation on the surface of the moon. Unfortunately the numbers are not pretty, the base Radiation level on the surface of the Moon is approximately 200 times more than the base Radiation level on the surface of the Earth. Even when we compare it to the level on the ISS, it turns out that the moon has over 2.6 times higher radiation levels than the ISS making it very risky for unshielded humans to stay there for a long duration.

The only way to protect the astronauts is to shield their habitats and spacesuits. For the spacesuits there is ongoing research to identify the best material for shielding (lead works great but is heavy) and for the habitats the cheapest and most effective option would be to just build the whole thing underground. The lunar soil would act as a shield to protect the interior and best of all it doesn’t require us to lift heavy shielding material into orbit reducing the cost of the missions. As per the team’s calculations burying the habitat under ~30 inches of lunar soil would give it protection equivalent to ground level on Earth.

For the assessment of the radiation exposure, the relevant quantities have to be measured by the detector systems: The absorbed dose, D, is the ratio of the energy (E; usually measured in keV) deposited in a detector and the mass, m, of the detector and is expressed in units of Gray (Gy = J/kg). Division by the accumulation time results in the measured dose rate (expressed in Gy/hour). Using a combination of two detectors in coincidence, one measures the distribution of energies deposited in a detector to obtain the linear energy transfer (LET) spectrum [usually in units of keV per micrometer (keV/μm)]. This spectrum is integrated with so-called quality factors, Q, used as biological weights to obtain the dose equivalent, H, which is expressed in units of Sievert (Sv = J/kg). The exact procedures are defined by the International Commission on Radiation Protection (17). Because the human body is not made of silicon, and to make dose, dose rate, and LET measurements more easily comparable to others, one normally converts the values measured in Si to the corresponding quantities in water using a constant dose conversion factor of 1.30 (18).

The Lunar Lander Neutrons and Dosimetry (LND) experiment is described in more detail in the literature (19), but we summarize the pertinent information here for convenience. The LND is mounted in the payload compartment of the Chang’E 4 lander. The red arrow in Fig. 1 points at the reclosable door that protects LND from the cold lunar nights but is open during lunar daytime. The LND consists of a stack of 10 dual-segment silicon solid-state detectors (SSDs), A to J, as shown in the main part of Fig. 2. Total absorbed dose and dose rate are measured in detector B, and the absorbed dose (rate) from neutral particles is measured in the inner segment of the C detector, C1, with the closely spaced detectors B and D as well as the outer segment of C, C2, serving as anticoincidence to discriminate against charged particles. The LET is then determined as discussed above from the dE/dx measured using three different combinations of detector pairs with different counting rates and average path lengths. Penetrating particles are measured by requiring signals in all 10 detectors.

More details of the research are available on the paper published in the journal Science Advances late last month. Check it out if you are interested in learning more technical details about the project.

Source: Businessinsider.in: After measuring radiation on the moon for the first time, scientists say a lunar base should be built underground to protect astronauts

– Suramya