Hopeful and confident about the future.

obtuse/optimistic/omniscient

(a)  

The forming of a theory or conjecture without firm evidence.

specialised/speculation/spared

(a)  

A person who studies astrobiology.

astrobiologists/astrophysicist/astronomer

(a)  

A person engaged or learned in philosophy, especially as an academic discipline.

philosopher/philandrist/philanthropist

(a)  

Administer baptism to (someone); christen.

bauble/baptise/brag

(a)  

A person or thing dismissed as inadequate or unacceptable.

revitalise/revamp/rejects

(a)  

Suitable or good enough to live in.

horrible/habitable/horrendous

(a)  

Absolutely necessary; extremely important.

extreme/extrude/essential

(a)  

Existing or available in large quantities; plentiful.

abundant/abhor/abreast

(a)  

Relating to, denoting, or preserving the character of an early stage in the evolutionary or historical development of something.

pretense/primitive/pristine

(a)  

A microorganism, especially a bacterium causing disease or fermentation.

macronutrients/microbes/mitosis

(a)  

An animal lacking a backbone, such as an arthropod, mollusc, annelid, coelenterate, etc. The invertebrates constitute an artificial division of the animal kingdom, comprising 95 per cent of animal species and about thirty different phyla.

inverted/invertebrates/intertwined

(a)  

Expressing approval.

flimsy/fraught/favourable

(a)  

Relating to movement towards a centre of gravity.

gravitational/gratitude/grained

(a)  

Having or seeming to have no end or limit.

ending/endless/endear

(a)  

(Of a value or number) roughly calculated; approximate.

estimated/estrange/eager

(a)  

Of very great extent or quantity; immense.

venture/vanguard/vast

(a)  

An organization having a particular purpose, especially one that is involved with science, education, or a specific profession.

institute/instinct/intrigue

(a)  

The ability to acquire and apply knowledge and skills.

intrepid/intern/intelligence

(a)