Re: Russia and ESA start to Mars and Venus again

From: Hop David (hopspageHATESSPAaMmM_at_tabletoptelephone.com)
Date: 02/03/05 

Date: Thu, 03 Feb 2005 14:53:27 -0700

Pat Flannery wrote:
>
>
> Hop David wrote:
>
>>
>> This is what I get:
>>
>> Depart DV Arrive DV Total DV Trip time Window each
>> Earth to Mars 2.94 km/s 2.49 km/s 5.59 km/s .71 years 2.14 years
>> Earth to Venus 2.65 km/s 2.71 km/s 5.20 km/s .40 years 1.60 years
>>
>> These are for Hohmann transfers between circular, coplanar orbits.
>> Mars can vary substantially from this ball park because of its more
>> eccentric orbit.
>
>
>
> So Venus is actually more favorable as a rule? I was basing my
> assumption on the high DV required to reach Mercury, and thought Venus
> would show a similar effect, but to a lesser degree.

The solar gravity well gets dramatically steeper close in. But Venus is
a little closer to Earth than Mars (.52 AU vs .28 AU).

If you're interested in playing with different scenarios you can
download my Excel spread*** at
http://clowder.net/hop/railroad/Hohmann.xls

Typing in departure and destination planets will give you launch
windows, Hohmann entry and exit DVs, trip times.

It also tells you how much delta vee is needed to exit or enter various
planetary orbits, allowing you to set peri and apoapsis.

Pluto's not included because it's inclination and eccentricity are too
different from my simplifying circular and coplanar assumption. (Though
I will occasionally use its absence to needle those who are adamant that
glorified Kuiper Belt Object is a planet).

> A Soyuz-booster launched Venus mission has economy on its side compared
> to a Proton one- and who knows? Maybe with the advances in electronics
> and computer technology they can do pretty near as much as the earlier
> Proton-launched probes...they're still going to have a hard time beating
> Vega 1 and 2 for a cool mission profile though...those two were really
> impressive.
>
> Pat 

-- 
Hop David
http://clowder.net/hop/index.html
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