New answers tagged

6

How has life of the orbiter increased from 1 year to more than 7 years? The stated one year operational period represented the pre-mission plan. That pre-mission plan had to provide enough delta V to transfer the vehicle from an insertion orbit to a more eccentric Earth orbit, then to a lunar transfer orbit, then to an eccentric lunar orbit, then to a ...


1

The lifetime probably didn't increase. Only the estimate increased. Due to uncertainties in any space mission we tend to err on the side of conservatism when advertising mission life; if we are fortunate we later add to the mission. The NASA Mars rovers Spirit and Opportunity were "supposed to" last 90 days or 90 sols (not sure which), we all know how ...


2

Aluminum manufactured into nano-sized particles can be mixed with water ice to make a fuel called ALICE. NASA has already flown a small rocket using ALICE. ALICE fuel Wikipedia Entry Another option is to use pure water with a nuclear engine heating it to extremely high temperature. This would work for point-to-point hops or trips from lunar surface to ...


4

There is no problem running Kerosene and Oxygen on the same turbopump shaft, at any temperature. provided both are liquid, the density variations are not sufficient to make any practical difference to the feasibility of a turbopump. From the OP, the densities of Oxygen and Kerosene are 1.18 and 0.8 g/cm3 , a ratio of 1.475. The pressure produced by a single ...


5

Red fuming nitric acid is used as a storable non cryogenic oxidizer. It does not leak, its fumes are vented, I guess to prevent a tank overpressure. From this pdf Problems in Storage and Handling of Red Fuming Nitric Acid So there might be too few NO2 and H2O within the mixture. Adding water would be dead weight, but 2 to 3.5 % should not be a problem.


5

This answer is largely speculative but based upon knowledge of similar systems. The Safir space launch vehicle may use hypergolic propellants. The launch site shown in the photograph has minimal permanent infrastructure. Hypergolic propellant storage facilities at Johnson Space Center and White Sands Test Facility have burner stacks to safely dispose of ...


2

Selecting the ideal propulsion system for a mission is closely tight to your requirements. You are typically interested in providing a given $\Delta V$ for a vehicle using an amount of mass (both the dry mass of the propulsion system $m_d$ and propellant $m_p$) and power $P$ over a period of time $\Delta t$. Considering these parameters you select the ...


0

There is no such thing as an ideal propulsion. The choice of a propulsion method is always, always a trade-off between various, often conflicting requirements. To name a few: price; performance; mission timeline; production/sourcing delay; state-of-the-art in propulsion; environmental & safety hazards. For example (very hypothetical): you work at a ...


Top 50 recent answers are included