- Astra is a beyond-visual-range air-to-air missile (BVRAAM) developed by India's Defence Research and Development Organisation (DRDO). It is designed to be launched from fighter aircraft. - Akash is a medium-range mobile surface- to-air missile defence system developed by DRDO. - Becquerel (Bq) is the SI derived unit of radioactivity. - Prithvi is a short-range surface- to-surface ballistic missile also developed by DRDO.