Environmental Engineering Reference
In-Depth Information
Launching1
PreLaunch
Early Launch
Late Launch
VVEJGA
FIGURE 5.7
Launching.1.event.
Table 5.3..The.results.in.Figure 5.8.were.generated.by.the.calculations.for.all.
steps.from.Figure 5.6.and.Table 5.3.
The.break-even.orbital.location.for.the.two.systems.is.4.183.AU,.where.the.
heavier. mass. of. the. system. is. changed. to. the. photovoltaic. battery. system..
Therefore,. in. the. journey. beyond. the. Mars. orbit,. the. RTG. system. has. the.
priority..This.means.nuclear.power.is.more.economical.for.deep.space.travel..
As. far. as. safety. is. concerned,. the. SD. method. is. used. because. it. is. appro-
priate. for. a. nonlinear. scenario. such. as. space. travel.. There. are. two. kinds.
of. the. results. in. Figure 5.8.. Figure 5.8(a). shows. the. RTG. system. case. and.
Figure 5.8(b).shows.the.photovoltaic.battery.system..The.maximum.value.is.
seen.in.year.50,.as.shown.in.Table 5.3..The.initial.difference.between.the.two.
failure.frequencies.is.just.10%..The.last.difference.is.97.5%,.which.means.that.
the.failure.frequency.increases.as.time.passes.
5.5 Conclusions
The.comparisons.of.two.kinds.of.deep.space.explorer.craft.success.rates.were.
investigated..The.failure.frequency.of.the.RTG.is.less.than.that.of.the.pho-
tovoltaic. battery. system.. The. assumptions.are. that. the. distance. of. travel. is.
decided.by.the.following.calculations:
•. The. optimized. battery. mass. and. RTG. mass. for. the. space. travel. is.
obtained.
•. The.suitable.breakeven.distance.is.decided.for.the.proposed.space-
craft.case.
•. The.space.nuclear.power.is.calculated.for.the.trip.out.of.Mars.orbit.
(about.2.67.AU).
A. solar-powered. mission. to. Jupiter. planned. by. NASA. is. called. Juno..
Juno's.trajectory.will.use.a.gravity-assist.speed.boost.from.Earth.that.will.be.
accomplished.through.an.Earth.lyby.two.years.after.its.launch.on.August.
5,.2011.(NASA.2011)..The.distance.is.from.4.950.AU.in.perihelion.to.5.458.AU.
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