Orbital Drop Shock Trooper

ODSTs are introduced in the fictional world of the Halo video game and book series. Highly skilled and trained, the ODSTs are a special forces outfit (105th regiment) of the UNSC Marines.

ODST (Orbital Drop Shock Trooper)
The ODSTs, as their name implies, are dropped from low-orbital positions onto the surface of planets (or in the case of both Halo rings, ancient artifacts), often into combative situations. They are deployed via HEVs (Human Entry Vehicle), one-man pods designed to carry soldiers to their drop point. Once at their destination, the ODSTs have to move quickly, regrouping, securing a perimeter, and treating to those less fortunate of their ranks.

Helljumpers
The 105th regiment of the UNSC Marine Corps is an entirely volunteer outfit, and for a good reason. The HEVs, following deployment, heat up immensly due to atmospheric friction, sometimes fatally so. Even if the ODST survives the heat, there's always the chance that his HEV won't. As experienced by Major Antonio Silva in The Flood, the pod's outer layers sometimes get stripped away, leaving the ODST to face the elements with nothing but his combat armor. The third and by far worst forms of a falling ODST's fate is chute failure. The HEV's descent achieves such high velocities that the chance of the parachute failing to slow the pod is an ever-present threat. The HEVs are armored, but not enough so to protect an ODST from an over 400 km/h descent from orbit.

Feet First Into Hell
ODSTs (Also known as "Helljumpers") are highly-skilled, versatile, and lightning-fast to deploy, but their job is incredibly demanding and extremely high-risk. Because of the intense heat the Helljumpers have to suffer through with every drop, they adopted the phrase "Feet First Into Hell" as their motto. It symbolizes their willingness to literally jump into extreme danger in order to help others.