China's Long March 4B rocket booster explodes into a massive cloud of orange smoke after crashing into a nearby town and narrowly missing a school

[DrQ]

I saw the orange cloud and knew immediately that they were using hydrazine and nitrogen tetroxide for their propellant, run away, run away, run away.

China's rocket booster explodes after crashing into a nearby town

China's Long March 4B rocket made a crash landing following a launch of a satellite into orbit. Footage of the incident shows the rocket falling from space and crashing into a nearby town.

www.dailymail.co.uk

It's a variant of the devil's brew that caused the Nedelin catastrophe that doomed the Russian moon program. It has a high specific impulse, but AFIK we only use it for thrusters, not main engines.

The oxidizer (nitrogen tet) is so corrosive, it is difficult to maintain the hardware for fueling.
And then there is hydrazine:

Hydrazine exposure can cause skin irritation/contact dermatitis and burning, irritation to the eyes/nose/throat, nausea/vomiting, shortness of breath, pulmonary edema, headache, dizziness, central nervous system depression, lethargy, temporary blindness, seizures and coma.​

It is a precursor to several pesticides.

 

[DrQ]

Updated: I checked on Wiki and it looks as if their next gen rockets are using LOX/Kerosene in their first stage boosters.

Side note: The Russians used to use that witches brew for their submarine based ICBMs before they developed Solid Rocket Motors.