ISRO Interview Experience & Tactics
The ISRO Interview Guide
Getting an interview call from ISRO is a major milestone but it’s not the finish line. In the ICRB selection process, the interview is where everything is decided. Your concepts, clarity, confidence, and mindset as a future engineer are tested in depth.
The biggest problem most aspirants face is the lack of clear guidance. What actually happens inside the interview room? What kind of technical questions are asked? How do top rankers prepare—and what mistakes cost others their selection?
This blog answers all of that. Based on real interview experiences of candidates who have successfully cleared the ISRO Scientist/Engineer ‘SC’ interview (including top rankers), this is a complete, practical guide covering every stage—from entry to exit.
๐ What This Guide Covers
- ๐น Complete ISRO ICRB Interview Process (Step-by-Step)
- ๐น What Happens From Entry to Exit
- ๐น Technical Questions Asked (Real Examples)
- ๐น Preparation Strategy Used by Selected Candidates
- ๐น HR & Personal Questions Breakdown
- ๐น Common Mistakes to Avoid
- ๐น Final Tips from Selected Scientists
1. The Interview Setup & The Panel
When you walk into the room (or join the virtual feed at a regional center), you won't be facing just one or two people.
- The Panel Size: Expect 10 to 12 senior ISRO scientists from different centers across India.
- The Breakdown: Each member is an expert in a specific domain. There will also likely be 1 or 2 HR members observing your personality and communication skills.
- The Scoring System: The interview is out of 100 marks. Usually, each panel member holds roughly 10 marks. To qualify and get a job, you generally need to score in the 60s. Toppers usually score around 73 to 74 marks. It is a very fair and transparent system because the exact same panel travels to different centers across the country for your specific branch.
2. What Documents Do You Need?
Based on past interviews, here is what they typically ask you to bring (or upload beforehand):
- Original Call Letter
- Valid Original Photo ID and a photocopy
- NOC (No Objection Certificate) if you currently work in a Govt/Semi-Govt organization
- Declaration form (downloaded from their website)
- TA/DA form for travel reimbursement
3. The Flow of the Interview
ISRO interviews are completely different from BARC interviews. While BARC might grill you for over an hour deep-diving into one concept, ISRO is about speed and breadth.
- Duration: Most interviews last 20 to 25 minutes but some candidates have reported interviews stretching up to 40–45 minutes. A longer interview does not necessarily mean you are selected it simply depends on the depth of discussion.
- Number of Questions: You will be asked roughly 10 to 12 questions. That gives you about 1.5 to 2 minutes per question. They are in a hurry, so you need to be quick.
- "Introduce Yourself": This is guaranteed to be question number one. Do not improvise this. Write it down and practice it 50 times in front of a mirror. Mention your 10th, 12th, B.Tech percentage/CGPA, current job (if any), and hobbies (if they ask you to elaborate). This sets your initial impression.
4. The "Favorite Subjects"
The panel will ask you to name 3 to 5 of your favorite subjects. Do not assume they will only ask from these.
- The Reality: While some candidates find that 70-80% of their questions come from their favorites, others find their favorites completely ignored. If 20 mechanical engineers in a row say "Thermodynamics and SOM," the panel gets bored and will start asking about Industrial, Production, or Material Science just to change things up.
- The Strategy: Prepare your 5 core subjects at a level slightly above GATE. Read standard reference books for these because they expect you to have studied deeply during the gap months. However, you must revise the GATE-level basics for all other subjects in your branch. One top ranker actually prepared for 11 subjects just to be safe.
5. Types of Questions & Board Work
They usually start with basic theoretical questions, move to small numericals (that test your thought process and don't require a calculator), and then push into derivations.
- The Whiteboard: You will very likely be asked to stand up and go to a whiteboard.
- Projects: If you are an M.Tech student, your final year project is highly critical—know it inside out. For B.Tech students, having a basic idea of your project is usually enough, though sometimes they skip it entirely.
- General Awareness: Have a basic understanding of recent ISRO launches, upcoming missions (like Gaganyaan), launch vehicles, and even recent mission failures.
6. Golden Tactics for the Hot Seat
- Dress 100% Formal: Look the part. Wear a clean, ironed full-sleeve white shirt, black pants, black shoes, black belt, grey socks, and a tie. It gives you a psychological edge and shows respect.
- Language: You can answer in Hindi if you are more comfortable, but English is preferred and highly recommended, especially since the HR members are judging your communication.
- Do Not Bluff: Do not use heavy jargon (like "transient state analysis") unless you are ready to be grilled on it by a 30-year veteran scientist. If you don't know the answer, just say, "I am sorry, I am not able to recall this right now." Skipping a question quickly is better than wasting 3 minutes giving a wrong answer and failing the cross-questioning.
- Think Out Loud: If you sort of know the approach but aren't 100% sure, say: "I don't remember exactly, but let me try." Show them your thought process. They appreciate honesty and logical deduction.
7. Real Technical Questions Asked in Past Interviews
To give you an idea of the depth, here are exact questions asked to mechanical engineering candidates in recent panels. Use these to test your own prep!
Material Science:
- What are Inconel, Monel, Hastelloy, and Superalloys? What are the specific elemental differences between them (e.g., copper in Monel, nickel content, etc.)?
- What is Cast Iron and what is its carbon percentage?
- Explain the different types of Cast Iron: Grey, White, Nodular, Malleable.
- Why does Nodular Cast Iron form spheres/nodules?
- Why is Grey Cast Iron used for Lathe machine beds? (Answer: High damping capacity).
- Go to the board and draw the TTT (Time-Temperature Transformation) diagram and explain it completely.
Machine Design & Mechanics:
- Design a bolt. What is the relation between torque and force?
- Why is pre-tension/pre-compression given to a bolt?
- What forces act on the threads of a bolt during working?
- Name different types of threads (Acme, V, Square, Buttress). Which one has the highest efficiency?
- What specific thread is used in the lead screw of a lathe?
Production/Manufacturing:
- What is Investment Casting?
- What is the exact difference between Investment Casting and Sand Casting?
Miscellaneous/Application Based:
- Who needs a higher Factor of Safety: a Car or an Aeroplane?
- Explain the difference between the Rankine Cycle and the Brayton Cycle.
Your technical knowledge makes up 90% of the interview, but your confidence and ability to express that knowledge make up the other 10%. Don't just sit and read books—stand up, speak out loud, and practice explaining your concepts.
You already cleared the written exam, which means you have the knowledge. Now, it's just about holding your nerve. Keep preparing, stay confident, and good luck!
ISRO Interview summary
- The panel consists of 5-10 senior scientists, IIT faculties etc.
- They may ask you to choose your top 3-5 favourite questions. They may or may not ask questions from your favourite subjects.
- You need to give a full explanation of every question/topic asked.
- Be familiarized with Blackboard teaching as you may have to explain on the blackboard.
- They may ask you about your B.Tech final year project. But It completely depends on them.
- For M.Tech students prepare well the M.Tech thesis topic.
- Reach the interview venue before time.
- Check all documents, a day in advance.
- Don’t forget to keep a pen with you in the interview room.
Interview Transcript #1: Mechanical Engineering (Secured AIR 3)
Date: 3rd August 2018 | Location: Delhi
I reported there in the early morning at 8 AM, but I was the last to be interviewed that day. I finally got into the interview room around 8 PM. As I entered the room, there was a panel of 10 members and a Chairman. I wished them, and they asked me to introduce myself. But after 2–3 lines, they stopped and started bombarding questions from various subjects. Since I was the last candidate, they were bored with subjects like Fluid Mechanics, Heat Transfer, and SOM. So, they started with Material Science.
๐ฃ️ Panel Member 1 (Material Science)
๐ฃ️ Panel Member 2 (Project Based - Crack Propagation)
As I wrote about a crack propagation project in my bio-data form, she asked me questions regarding that.
๐ฃ️ Panel Member 3 (Core Mechanics & Thermodynamics)
The Verdict & Final Advice
Finally, my interview was over. The panel was sometimes sarcastic and sometimes cooperative. I was shivering there while standing, so they called me to a chair and asked the remaining questions from thermodynamics. They laughed very often—I don't know why. Whether it was at foolish answers or because they were impressed, it's difficult to guess.
My interview was around 35–40 minutes. I left the room at 8:35 PM and ran away from the building as I didn't want to face the interview panel members. I thought my interview was not that good as they laughed at me a lot. But after 20 days, the result came... I was in shock and also very, very happy as my name appeared in the list on the third position (AIR 3).
"For all candidates preparing for the interview: please prepare at least 4 subjects. Questions are not that difficult, but sometimes if you take more time on a particular question and don't deliver it correctly, it will lead to a loss of your interview time. So be honest… if you are not sure or you don't know the answer, be genuine. Directly tell them you don't know. This will allow them to ask other questions which you can answer. I personally answered 70 percent of questions, but still, I was able to secure a good position. Don't make wild guesses."
Interview Transcript #2: Mechanical Engineering
Candidate: Munish Kumar Sharma | Date: 17th April, 2021 | Location: URSC, Bengaluru
After a brief introduction, the Chairperson asked me to tell them my favorite subjects. I told them that my favorite subjects are Mechanical Vibrations, Mechanics of Materials, Engineering Mechanics, and Engineering Thermodynamics.
๐ฃ️ Interviewer 1 (Vibrations & Modal Analysis)
๐ฃ️ Interviewer 2 (Drawing & Metrology)
๐ฃ️ Chairperson (Manufacturing)
Chairperson (smiling): Thank you Munish, you can leave. Have a good day ๐.
Interview Transcript #3: Mechanical Engineering
Once i have attempted the interview of I.S.R.O. for the post of Scientist.
first let me describe about panel.
There are a total of 9 people in panel(sometimes 8 people) sitting at a round table.
Right in front of you is the chairman ( his chair is slightly different). Most of the people are retired professor of IIT's, NIT's or reputed universities. one person is from ISRO & one is HR member who generally don't ask question but only observe you.
for a student (you) they provide a table (not the chair ☺️)to seat.there is a blackboard behind you where you have to explain your answers.thats why they provide table so that you do not have problem to getting again and again.
Now how should you be preapared.
Always enter with permission. Always first wish female there after male( keep remember about morning,afternoor or Evening). Seat only whey they said to seat. be attentive in seating you have to seat on table not in chair. From few days before of interview, practice to write on black board. Keep on explaining while writing. Dont be irritate .they can tell you to seat or go to black board four to five times in two minutes. Be attentive , sometimes two person ask the question simultaneously. actully they want to check your patience level. what you have to Read
Be confident in your college final year project.Sometimes your whole interview will be on your project. they asked me about summer training. Prepare three to four technical subjects. they dont ask very deep like BARC or NPCIL.they are intrested in basic only. ISRO intervew will be 20–25 minutes only so you have to proof yourself in this time.
There is no any reservation in ISRO
Q Asked to me in my interview
what was your final year project?? can, you draw block diagram of your project ?? As you have done your summer traing in railway, can you tell me what type of bearings are used in axle wheel?? have you heard about hybrid bearings?? If you have two option to choos a bar a) Aluminium, b)steel what will you choose condition is — rod is hanging from top ,cross section shape is sqaure,a load of P newton is hanging from bottom. most of the dimensions they provided like density of Al-2700,Steel-7800. they also said that plz consider self weight also.they also provide a diagram for it like this one-
draw the stress strain diagram on a single graph for Al and mild steel?? what is kinetic energy?? And what is potential energy? is temperature has any role for kinetic energy?? Best of luck,๐
Interview Transcript #4: Mechanical Engineering
After a brief introduction, they asked my fav. Sub they are as follows HT, MD, FM, Thermo.
- What is max stress in a bar which is hanging vertically?
- If I want to design this bar what will be the min length I should take?
- If I put the whole system in water then whether the length increase or decrease?
- How many laws of thermodynamics u know? What is the first law of thermodynamics?
- Draw adiabatic process on pv chart?
- What are the conditions of the adiabatic process?
- Derive PVฮณ=c ?
- Draw two stage and one stage compressor?
- What is intercooler? What amount of work has been saved by intercooling?
- What if I do aftercooling ( means one more intercooler after 2nd stage)
- I want to manufacture the glass (pointing glass present in front of interviewer) so draw a drawing of glass?
- Then they asked last q. From one of my extracurricular activities, in that I attended workshop on rubber powered aircraft so they ask what is it?
ISRO Interview Experience 5 (AIR-1)
There were 9-10 people including one female member sitting around U shaped table.
Chairman- good afternoon. Please introduce yourself.
Me- good afternoon mam and sirs. My name is Rajat Kumar Singh, I told them about my schooling, college,etc..(it was very short introduction). And my areas of interests are ENGG. MECHANICS, SOM, HMT, FLUID MECHANICS and MACHINE DESIGN.
(actually,i was not fully prepared for machine design so slowly told “machine design”)
M1- what is your last subject?
Me – sir Machine design.
(i thought ab to gya mai)
M1- ok rajat, what is fail-safe approach?
Me- after 3-4 second, sir it is an approach in designing, we design our system or machine in such a way that there is minimal loss in terms of money and safety. For example, in the design of shaft and key, we make our key weakest member. In boiler design also we provide safety valve so that in case of overpressure our boiler will be safe.
M2- Take a marker and draw a thick cylinder.
Me- i made two concentric circles.
M2- how will you classify thin and thick cylinders?
Me- sir if the wall thickness is less than about 7% of internal diameter we treat it as thin otherwise thick.
M2- okay, draw one more cylinder over it and there is fluid inside it. Tell me how will hoop stress vary for both cylinders?
Me - DRAWN
M2- what if there is external pressure and no internal fluid?
Me- drawn.
M2- good
M3- draw one cantilever with a point load at one end. Tell me the deflection at the free end.
Me: (trying to impress, started deriving the formula)
M3- just tell me the formula
Me- WL^3/(3 EI)
M3- cut it in two pieces and tell me about shear forces at different points.
Me- drawn two half beams and showed the shear forces.
M3- draw its shear force and bending moment diagram
Me- drawn easily.
M3- how will shear stress vary?
Me- drawn transverse shear stress variation.(D shaped)
M3- what is the relation between average and maximum shear stress?
Me- 3/2 times of average.
M3- What if beam is circular?
Me- 4/3 sir.
M4- there is a rectangular beam hanging with a cable on a crane. The weight of beam is 10 tonnes. Angle b/w cables is 60 degree. What will be tension in the cable?
Me- (drawn) suppose weight is uniformly distributed then at each ends weight is 5 tonnes each. Applied force balance and calculated tensions easily.
M5- do you know projectile motion?
Me- yes sir.
M5- at what angle the range is maximum?
Me- at 45-degree sir(smiled)
M5- write rigid body equation of motion?
Me- d(m*v)/dt = F (i don’t know it was right or wrong but they smiled).
(i was thinking inko bhukh ni lagi kya :p)
M6- if I give you perimeter= 12 m can you find the dimensions for the maximum area?
Female member(F)- Rajat I think you are tired now take a seat.
Me – thank you, mam.
F- we will ask something related to ISRO. Do you know what was last mission all about?
Me- mam it was the launch of PSLV C39. India is developing its own GPS, for that we already sent 7 satellites but mam there was some problem in one of the satellites. So we were replacing that satellite with a newer one. This mission was unsuccessful because heat shield did not separate.
F- what is heat shield?
Me- this is like a cover for our payload. Due to air resistance, surface temperature increases enormously. To protect our payload we use heat shield.
F- we are done now. Thank you.
Me- thank you mam
(everyone was smiling, a big sign of relief at that moment)
My interview went for about 35-40 minutes. This was purely technical. The main thing is if you are not very well prepared don’t be nervous. In introduction only tell them about your favorite subjects. They didn’t ask about my project. I answered almost everything but if u don’t know the answer tell them directly.
I got 83.11 in the final result.
Interview Transcript #5: Mechanical Engineering
After introduction chairman asked me favourite subjects and I replied SOM TOM MD and HMT Power Plant and then a rapid fire round of 30 minutes started.
- Define degree of freedom for a mechanism. What is the degree of freedom in space and plane?
- What is Grubler’s formula to find dof of mechanism?
- Draw a mechanism having all revolute pairs with 5 links and find dof.
- Then in the same mechanism he told me to fix another link and asked what will be effect on dof?
- What is redundant link and redundant dof?
- Name different types of gears
- Comparison between involute and cycloidal profile.
- Draw tooth geometry and show pressure angle.
- What is contact ratio?
- What is path of contact and show when there will be first contact between teeth of gears?
The session of TOM was about to end but then chairman told that you have classified all types of gears but forgot one i.e. epicyclic gear train. I think he wanted me to also show internal gearing.
- Draw epicyclic gear train and find dof.
- Draw universal joint. Does the velocity ratio in universal joint remain constant or vary? If varies then write formula and show variation of velocity ratio with angular position of shafts.
Then some questions from Heat Transfer:
- Suppose a cuboid in furnace at 300°C is brought suddenly to room temperature then write governing differential equation and show temperature variation with time.
I drew exponential decreasing curve and he was asking why curve is not touching room temp. line why it is going to infinity? So this was a short session of Heat Transfer and then suddenly an interviewer asked:
- What is balancing and types.
- Tell me the necessary condition for a rotating disk to be balanced.
Interview Transcript #6: Mechanical Engineering
First, a bit of a background. I did my mechanical engineering from a decent state level university college and I got placed into IBM in the final year. Having no other options, I joined IBM after college. But I wanted to work in a field of my engineering background, and so I also took up GATE coaching at ACE Academy. I got a rank of ~4000 in GATE 2016. Since I didn't get into any PSU or IIT with this rank, I had to continue looking for other options, which is when I applied to ISRO.
Now, coming to the experience, let me give you an overview of the selection process. There's 2 stages for ISRO recruitment. First is a written exam, 80 questions, 90 minutes. 3 marks for correct answer and a negative mark for each wrong answer. You can look up the syllabus on their website. The board uses the exam as a way to shortlist candidates for the interview. Your selection depends only on your performance in the interview. The candidates are called for the interview in the ratio of around 89 candidates per post.
For preparing for the exam I only revised the notes I had prepared for GATE and then went through all previous year question papers. I bought this book which had previous question papers for ISRO and DRDO (MADE EASY Publications). I felt the ISRO exam requires time management as we had to answer more questions in lesser time for this exam (unlike GATE where time constraint is not felt). To get used to this, I set a timer and wrote the previous exam papers as though I am writing the actual exam. Then I made a list of questions I made mistakes in, and a list of theoretical questions for which I didn't know the answer. Revised these questions again before the exam once.
I managed to get 140/240. The cutoff was around 130 I think. I was requested to come to NRSA Hyderabad for the interview. I contacted one of my tutors from ACE academy and requested for help in preparing for the interview. He arranged a mock interview with the senior faculty at ACE. The director of the institute also spoke to me and gave me tips to prepare for the interview. A big thanks to all of them :).
The reporting time for the interview was 8 AM. But I was the second last person to be interviewed and my interview happened at 9 PM. Despite the long and boring wait, I went into the interview hall with a lot of energy and a big smile on my face. There were 6 panel members and a chairman. The chairman asked me to explain what I work at IBM (I work on an ERP tool). Then he asked me to explain.
Interview Transcript #7: Mechanical Engineering
The panel consists of 10 people including the chairman. The interview was purely technical. It went on for about 30 to 40 minutes. After entering the hall: Good Morning/evening everyone!
Questions:
- Tell me about yourself.
- What are your favorite subjects (like fluid dynamics, heat transfer, SOM, heat transfer, and fluid dynamics)?
- What is irrotational flow?
- What is the deciding factor for the flow?
- What is a streamline?
- What is a pathline?
- Which one is the Eulerian approach and which one is the Lagrangian approach?
- What is the condition for the highest point in the siphon?
- What is the maximum height of the siphon in the case of water?
- What is the stream function?
- What is the velocity potential function?
- What is the angle between them?
- If I give you material and I have to calculate the young modulus of elasticity. How will you do it?
- How will u calculate the strain?
- Where will you put the strain gauge?
- What are the modes of heat transfer?
- What are the types of convection?
- Do you have any idea about Rayleigh's number?
- So what will be the deciding value of Rayleigh number for natural circulation?
Interview questions may differ because it depends on your branch or post. I hope this will help you.
Interview Transcript #8: Mechanical Engineering
I would like to tell you that in the below question list some of the questions are asked based on candidates' individual skill set. So, it is not desirable to know every topic mentioned in below questions. But to be on safe side, please try to cover as much topics as you can. This will surely increase your chances to be selected in the interview.
ISRO Interview Details
- Panel may consist of 5-10 senior scientists, IIT faculty members etc.
- They may ask you to choose your top 3-5 favourite questions. They may ask questions from your favourite subjects or may not.
- You need to give full explanation of every question/topic asked. Be familiarized with Blackboard teaching as you may have to explain on blackboard.
- They may ask you about your B.Tech final year project but it completely depends on them. For M.Tech, students prepare well for the M.Tech thesis topic.
- Reach interview venue before time. Check all documents, a day in advance.
- Don't forget to keep a pen with you in interview room.
ISRO Interview Questions Mechanical
- Draw a thick cylinder. How will you classify thin and thick cylinders?
- What if there is external pressure and no internal fluid?
- Draw one cantilever with point load at one end. Tell me about the deflection at free end. Tell me the formula.
- Cut it in two pieces and tell me about shear forces at different points. Draw its shear force and bending moment diagram. How will shear stress vary?
- What is the relation between average and maximum shear stress? What if beam is circular?
- There is a rectangular beam hanging with a cable on a crane. The weight of beam is 10 tonnes. Angle b/w cables is 60 degree. What will be tension in the cable?
- In projectile Motion at what angle the range is maximum?
- Write rigid body equation of Motion.
- If I give you perimeter= 12 m, can you find the dimensions for maximum area?
- Do you know what was ISRO last mission all about?
- What is heat shield?
- What is the difference between Centripetal and Centrifugal Force?
- Can they ACT on a body simultaneously?
- Tell me difference between Governor and Flywheel. Factors to be considered for designing flywheel, like mass, stiffness and other things. How it stores energy, how angular velocity gets changed?
- What is product moment of Inertia? What is its significance?
- What is Nusselt no.? Give practical exam.
- How can you join two objects without using Nut Bolt fixture?
Bonus: ISRO Interview Questions – The HR Round
ISRO (Indian Space Research Organisation) is one of the top six space organizations in the world along with NASA (USA), RKA (RUSSIA), ESA (Europe), CNSA (China) & JAXA (Japan). ISRO has covered a long distance since the launch of its first space satellite, Aryabhatta, in 1975.
While the technical round is the most rigorous, the panel will also gauge your personality. Here are some of the key HR and behavioral questions frequently asked during ISRO interviews, along with strategies to answer them:
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