Why are CEV drawings shown with solar panels?

[willpittenger]

Does NASA now prefer solar panels over fuel cells? Or is that one contractor's preference? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[vogon13]

Solar panel efficiency has really improved from the ~5% of the 1960's versions to the 30+% efficient units now available.<br /><br />No moving parts (except for aiming mechanism), lighter, higher reliablity, all move the practicality of solar cells over the complex and sometimes balky fuel cell technology.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

Please entertain the idea that the folks designing this stuff have to have good, sound engineering basis for their design tradeoffs.<br /><br />Component selection is rarely based on whim, capriciousness, or what's on sale at Radio Shack.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[cuddlyrocket]

The CEV is intended to both stay parked at the ISS, and later in lunar orbit, for up to six months. Fuel cells use oxygen and hydrogen continuously - for six months worth that's a lot of extra mass you need to carry. Solar cells get their power from the sun. For longer missions, they are far more mass-efficient.<br /><br />In the ISS case, the CEV could get power from the station's solar panels, but the ISS is actually power limited, so it would be helpful if the CEV could generate its own. In any event, it's not an option in lunar orbit.

 

[rybanis]

<blockquote><font class="small">In reply to:</font><hr /><p>"Does NASA now prefer solar panels over fuel cells? Or is that one contractor's preference?"<br /><br />Fuel cells make sense for the Shuttle Orbiter since the flight times are short. CEV missions are up to 6 months<br />for the first CEVs to the ISS and the Lunar flights. The croygenics to feed the fuel cells would take up too much weight.<p><hr /></p></p></blockquote><br /><br /><br />This thread made me realize, with the CEV, there won't be anymore APU failures causing early mission returns.<br /><br />(I do know the difference between fuel cells and APUs, by the way <img src="/images/icons/smile.gif" />) <div class="Discussion_UserSignature"> </div>

 

[radarredux]

> <i><font color="yellow">Solar panel efficiency has really improved from the ~5% of the 1960's versions to the 30+% efficient units now available.</font>/i><br /><br />Just a wild eyed thought... Has NASA looked seriously at providing power to spacecraft or Lunar bases via beamed power?<br /><br />I have seen the small radio controlled planes powered by lasers, Lightcraft Technologies little silver toy using lasers, and of course there always the stories of powering solar sails with lasers. But I haven't seen anythng serious for the near-term (e.g., 10-20 years).<br /><br />One of the problems with a Lunar base is that, with the exception of a few places at the poles, any location would need to endure ~14 days of darkness. This implies some type of nuclear power generator would probably be needed for long duration missions.<br /><br />For at least the near-side of the Moon, could enough power be economically beamed from the Earh to the Moon (Microwave, Laser, whatever) to some type of collector so that nuclear power (and the associated political headaches) could be avoided for long-duration Lunar missions?</i>

 

[rybanis]

Holy crap SG. Holy crap.<br /><br /><br />That would have looked good. Having the back end of an orbiter explode in front of everybody! <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

It's been looked at, but I don't think it is considered a viable option at this stage. Too much complexity and mass required.<br /><br />Jon<br /><br /><br /> <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>

 

[henryhallam]

I think it would be quite a "big deal", due to beam spread and the really long distance.<br />The LASER beams used with the retroreflectors left by the Apollo missions spread to something like 5 miles diameter by the time they reach the moon (and I think they are probably trying very hard to focus them tightly). So you would need a receiving array (or rectenna, for a MASER) that is pretty big if you hope to recover most of the power transmitted in the beam. Lots of infrastructure on the Earth as well, to provide continuous coverage throughout the day (and what do you do if it's cloudy?)<br /><br />Overall I think a small nuke is easier.

 

[ltm_se]

"One of the problems with a Lunar base is that, with the exception of a few places at the poles, any location would need to endure ~14 days of darkness. This implies some type of nuclear power generator would probably be needed for long duration missions."<br /><br />Since it will be a "full earth" during the 14 days of full moon it should be some light shining on the moon coming reflected from earth. Probobly not enough to generate solar energy but you should have some illumination.<br /><br />Gah .. hopefully in 20-30 years there will be hotels on the moon with skylight windows. Just imagine lying there in a big king size bed below the skylight observing the earth slowly rotating above you. =)

 

[rybanis]

I'm hoping that I can take my fiance into space one day. She keeps telling me that my mind is up there, so she'd like to see what I look like "at home" <div class="Discussion_UserSignature"> </div>

 

[rybanis]

We're both 22 now. Pehraps one day.<br /><br />The only thing is, shes already had cancer once in her life. Even if I was wildly optimistic and one day there was an option for us going into space, I'm not sure they would let cancer survivors into space (what with the cosmic rays and radiation and all). <div class="Discussion_UserSignature"> </div>

 

[rybanis]

Let us hope!<br /><br />I want my Clavius Base, and I want it now damnit! <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[ltm_se]

"No, when the Moon is full as seen from Earth, the Earth seen from the Moon is New, that is just a blue halo since the view is of the night side of Earth. I am sure you intended to post ..." during the 14 days of the New Moon"."<br /><br />Yes that was what i meant. Still. How much light is beeing reflected by a "full earth" onto the nightside of a "new moon"? <br />

 

[ltm_se]

"I understand enough to read a newspaper. I hope to verify that some day."<br /><br />You seem to understand a hole lot more then that. =)<br /><br />Anyways, thank you for your knowledge!

 

[rocketman5000]

According to the recent story on Livescience.com you shouldn't even retire for another 25 years, and should soon be able to live to 100. I'll see if I can scare up a link. That means you are due for a mid life crisis right about now....

 

[rocketman5000]

Here we go. Sorry it doesn't have a pretty text label. I can't keep that many windows open on 56k<br /><br />http://www.livescience.com/humanbiology/060221_retire_later.html ]

 

[rocketman5000]

try it now, I think I got it fixed

 

[lampblack]

Wow... medical science is figuring out how to help us live longer -- and the chief benefit is that we get to delay retirement for 20 years?<br /><br />There's something seriously wrong with that picture. <img src="/images/icons/wink.gif" /><br /><br />Sorry... yes... this is off-topic.<br /> <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>