5 years to Mars?

[cosmictraveler]

<p><font size="5">Depending upon the MASS of the spacecraft carrying the humans, gear, fuel , food and other stuff, it could take up to 5 years to get to Mars because it is not going to be traveling as fast as a robotic spacecraft with much less MASS would. MASS has everything to do with speed don't forget and a human flight to Mars would have to have an enormous amount of MASS .</font></p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p>It does not require many words to speak the truth. Chief Joseph</p> </div>

 

[shuttle_guy]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Depending upon the MASS of the spacecraft carrying the humans, gear, fuel , food and other stuff, it could take up to 5 years to get to Mars because it is not going to be traveling as fast as a robotic spacecraft with much less MASS would. MASS has everything to do with speed don't forget and a human flight to Mars would have to have an enormous amount of MASS .&nbsp;&nbsp; <br />Posted by cosmictraveler</DIV></p><p>That long a human mission to Mars&nbsp;is unacceptable. Too much crew radation exposure, to long in zero G, to hard on the grew's mental state&nbsp;and too much mass required for consumables. That is a really bad idea.</p> <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>From this linkhttp://www.space.com/scienceastronomy/090126-astronauts-bone-strength-loss.htmlA 14 percent decrease in bone "strength" in a 6 month period. I think this alone would kill a planned 5 year transit time. Even the 2-3 year plan talked about may prove to be to injurious to astronauts in the long run. <br />Posted by samkent</DIV></p><p>These sort of alarmist stories don't give the full story.&nbsp; The reality is once people return to gravity bone density returns to normal or near normal levels.&nbsp; As a result people can fly multiple long duration (= >four months, the minimum flight to Mars) flights.&nbsp; For example the following:</p><p><font face="Times New Roman"><font size="2">Sergei Krikalev 804 days (six flights, three long duration)</font></font></p><p><font face="Times New Roman" size="2">Sergei Avdeyev 748 days (three long duration flights, one more than a year)</font></p><p><font face="Times New Roman" size="2">Valeriy Polyakov 679 days (two long duration flights, one 14 months)</font></p><p><font face="Times New Roman" size="2">Anatoly Solovyev 651 days (four flights, three long duration)</font></p><p><font face="Times New Roman" size="2">Alexandr Kaleri 610 days (four long duration flights)</font></p><p><font face="Times New Roman" size="2">Viktor Afanasyev 556 days (three long duration flights)</font></p><p><font face="Times New Roman" size="2">Yuri Usachev 553 days (four flights, three long duration)</font></p><p><font face="Times New Roman"><font size="2"><span style="font-size:12pt"><span><span style="font:7pt'TimesNewRoman'">&nbsp;</span></span></span>Musa Manarov 541 days (two long duration flights, one more than a year)</font></font></p><p><font face="Times New Roman" size="2">Yuri Malenchenko 515 days (three long duration flights)</font></p><p><font face="Times New Roman" size="2">Alexander Viktorenko 489 days (four long duration flights)</font></p><p><font face="Times New Roman" size="2">Nikolai Budarin 444 days (three long duration flights)</font></p><p><font face="Times New Roman" size="2">Yuri Romanenko 431 days (three flights, two long duration)</font></p><p><font face="Times New Roman" size="2">Alexander Volkov 391 days (three flights, two long duration)</font></p><p><font face="Times New Roman" size="2">Yuri<span>&nbsp; </span>Onufrienko 389 days (two long duration flights)</font></p><p><font face="Times New Roman" size="2">Vladimir Titov 387 days (five flights, (two long duration)</font></p><p><font face="Times New Roman" size="2">Gennady Padalka 387 days (two long duration flights, third scheduled &ndash; ISS Ex 19 and 20)</font></p><p><font face="Times New Roman" size="2">Vasili Tsibliyev 382 days (two long duration flights)</font></p><p><font face="Times New Roman" size="2">Valery Korzun 386 days (two long duration flights)</font></p><p><font face="Times New Roman" size="2">Pavel Vinogradov 381 days (two long duration flights)</font></p><p><font face="Times New Roman" size="2">Peggy Whiston 377 days (two long duration flights)</font></p><p><font face="Times New Roman" size="2">Leonid Kizim 375 days (three flights, two long duration)</font></p><p><font face="Times New Roman" size="2">Michael Foale 373 days (five flights, two long duration)</font></p><p><font face="Times New Roman" size="2">Aleksandr Serebrov 373 days (four<span>&nbsp; </span>flights, two long duration)</font></p><p><font size="2"><font face="Times New Roman">Valeri Ryumin 372 days (five flights, two long duration, 8 months apart)</font> </font></p><p><br /><br />&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Depending upon the MASS of the spacecraft carrying the humans, gear, fuel , food and other stuff, it could take up to 5 years to get to Mars because it is not going to be traveling as fast as a robotic spacecraft with much less MASS would. MASS has everything to do with speed don't forget and a human flight to Mars would have to have an enormous amount of MASS .&nbsp;&nbsp; <br />Posted by cosmictraveler</DIV></p><p>Err... No.</p><p>If you send people to Mars (unless you use some of the more obscure byways of celestial mechanics you can't sending anything to Mars that takes longer than the minimum energy&nbsp;Hohmann transfer, which is ~80 months.&nbsp;This is the case whethere you are sending one tonne or a thousand tonnes. &nbsp;It takes only modest expenditures of additional propellant to reduce this to 6 months.&nbsp; </p><p>Jon<br /></p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

<p>Just to remind people there are five types of mission times dictated by celestial mechanics</p><p>OPPOSITION CLASS</p><p>One leg 6-8 months, the other 12-14 months, short stay.</p><p>CONJUNCTION CLASS</p><p>Each leg 6 months, 18 months surface stay</p><p>FLYBY MISSIONS</p><p>12-26 months total, short stays, the short missions have high dV requirements</p><p>SPRINT MISSIONS</p><p>12-14 months total, short stay</p><p>CYCLERS</p><p>Variant of flyby mission with multiple ferry craft (cyclers) allowing long surface stays.</p><p>Every Mars mission ever proposed uses one of these.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[neilsox]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> For example the following:Sergei Krikalev 804 days (six flights, three long duration)Sergei Avdeyev 748 days (three long duration flights, one more than a year)Valeriy Polyakov 679 days (two long duration flights, one 14 months)Anatoly Solovyev 651 days (four flights, three long duration)Alexandr Kaleri 610 days (four long duration flights)Viktor Afanasyev 556 days (three long duration flights)Yuri Usachev 553 days (four flights, three long duration)&nbsp;Musa Manarov 541 days (two long duration flights, one more than a year)Yuri Malenchenko 515 days (three long duration flights)Alexander Viktorenko 489 days (four long duration flights)Nikolai Budarin 444 days (three long duration flights)Yuri Romanenko 431 days (three flights, two long duration)Alexander Volkov 391 days (three flights, two long duration)Yuri&nbsp; Onufrienko 389 days (two long duration flights)Vladimir Titov 387 days (five flights, (two long duration)Gennady Padalka 387 days (two long duration flights, third scheduled &ndash; ISS Ex 19 and 20)Vasili Tsibliyev 382 days (two long duration flights)Valery Korzun 386 days (two long duration flights)Pavel Vinogradov 381 days (two long duration flights)Peggy Whiston 377 days (two long duration flights)Leonid Kizim 375 days (three flights, two long duration)Michael Foale 373 days (five flights, two long duration)Aleksandr Serebrov 373 days (four&nbsp; flights, two long duration)Valeri Ryumin 372 days (five flights, two long duration, 8 months apart) &nbsp; <br />Posted by jonclarke</DIV> I didn't realize the list was that long. How many of these people are still alive and healthy in 2009?&nbsp; Neil<br />

 

[JonClarke]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> I didn't realize the list was that long. How many of these people are still alive and healthy in 2009?&nbsp; Neil <br />Posted by neilsox</DIV></p><p>As far as I know all of them, although some are getting on a bit of course,<br /></p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>