The US Defense Advanced Research Projects Agency (Darpa) has recently commissioned three private companies, Blue Origin, Lockheed Martin and General Atomics, to develop nuclear fission thermal rockets for use in lunar orbit.
Such a development, if flown, could usher in a new era of spaceflight. That said, it is only one of several exciting avenues in rocket propulsion. Here are some others.
Chemical rockets
The standard means of propulsion for spacecraft uses chemical rockets. There are two main types: solid fuelled (such as the solid rocket boosters on the Space Shuttle), and liquid fuelled (such as the Saturn V).
In both cases, a chemical reaction is employed to produce a very hot, highly pressurised gas inside a combustion chamber. The engine nozzle provides the only outlet for this gas which consequently expands out of it, providing thrust.
Emergency medical services in the Czech Republic are becoming overwhelmed with Covid-19 patients. Ambulance workers have been under enormous pressure for several months now and with the recent upsurge in serious Covid-19 cases, they are often stretched to the limit.
In recent days, emergency services around the country have been responding to a record number of calls. For example the operation centre of the Prague Emergency Medical Service currently responds to around 700 calls a day. According to its spokeswoman and dispatcher Jana Poštová, the recent days have been the hardest since the start of the pandemic:
“People who call us these days are usually really sick. Compared to the past, most of the callers are in a very serious condition. They have low saturation of blood oxygen and you can hear even over the phone that they have problems breathing.”