IV standard is too early to put a load on the child to put prepare him for competitive exams or books required to become a space scientist but you can help him to be more active and like it with other supplies that will help him as he grows. Some of the tips to encourage him to reach his goal can be:
i) Focusing on the child's interests - It becomes easy for a parent to make his child focus on the subject of interest that their kid likes. As you have mentioned that your child aims to become a space scientist, help him with more details about it from other resources, books, write-ups, providing more about scientists, their work, their routine, etc.
ii) Develop reading habit - The more a child reads, the more he will love to learn and reading is the stepping stone to your child's growth. The more he reads about things, the more he will be interested in knowing about things and as he progresses, he will find his own ways of finding the path and will help him reach heights as we all know that a book is always the best friend a person can have.
iii) Learn different styles and types - There are different styles or types of learning like Verbal, Visual, Social, Audio, writing, etc. We need to understand the best way to make our child learn, he can be a good learner by just reading, some are good by just listening, some would learn by writing, etc and there is no right or wrong learning style. We need to find the best techniques that will improve our child's quality and learning ability.
iv) Stay organized - Help your child to be more organized by doing his own homework, packing bags, cleaning his table, etc as this will help him to be more patient, motivated, consistent and even prepares him to be ready for any task in the right time without being overloaded at the last minute.
v) Learn everyday - Let your child be active by exploring the world around him with questions and finding an answer about it. It can be like why the sky is blue? or why is the leaf green in color? or how do wifi work? etc. This will help him to develop internal motivation and an urge to learn more and more.
vi) Find out your child's strength - We often talk about the weaknesses of our child but never look at the positive strength which discourages him. We need to focus on his strengths and appreciate him for the achievement even though it is small as it will help him to be positive and motivate him to learn more.
vii) Never compare marks or performance - Many parents compare makes or grades and discourage their children for low grades or marks but we should always focus on his learning and not on his performance as this will help him to explore more on a subject that he likes and master it.
“The most important thing in life is to learn how to give out love, and to let it come in." — Morrie Schwartz