Ceres Vs Europa for robot lander?

[j05h]

I just finished reading the latest Planetary Report and it's excellent article on Europa and other water-rich minor planets. Europa is by far the choice of exploration for planetary scientists (besides Mars, of course) and is considered the most likely place for extraterrestrial life. The article indicated that Europa's prime candidancy for life/exploration is because it's salty ocean is sandwiched between the rocky mantle and ice covering. This allows for water-leached chemistry from the rocks to provide nutrients for any life. The thinness of the ice layer also allows solar-induced chemistry to recycle down into the ocean. Ganymede, Callisto and others are projected to have liquid layers between heavy and light ice layers, limiting available chemistry. <br /><br />Ceres is projected to be similar to Europa in structure, but is smaller and closer to Earth. It has yet to receive a robotic visitor from Earth, which limits this discussion somewhat. Dawn should help somewhat, for now we know it is a water-rich body with a conductive (salt water) layer and enigmatic surface features. Ceres is about half the diameter of Europa, about 950km vs 1500km diameter with significantly less gravity (.27m/s^2 vs 1.3m/s^2). Being located in the Main Belt of asteroids it experiences significantly less radiation than Europa - but doesn't have a major body nearby for aerobraking. <br /><br />Quick Info:<br /><br />http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)<br />http://dawn.jpl.nasa.gov/<br /><br />http://en.wikipedia.org/wiki/Europa_(moon)<br />http://galileo.jpl.nasa.gov/gallery/europa.cfm<br /><br />Oceans in the Outer Solar System -- And Not a Drop to Drink<br />by Robert Pappalardo<br />htt</safety_wrapper <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[solarspot]

I would say Ceres. Not because it is more interesting, I find Europa more interesting, but because of the ease of soft landing on the surface compared to the same for Europa. The latter is well inside Jupiter's gravity well, and aerobreaking can only reduce the apoapsis of the orbit, so there will still be a significant velocity difference between the landers elliptical orbit and Europa's circular one. Unless I had a budget big enough to use a JIMO style orbiter to deliver the lander to a low orbit, I wouldn't bother with Europa.<br /><br />[Edit - changed one word I didn't like]<br /><br /><br />

 

[3488]

Both IMO.<br /><br />True Solarspot that 1 Ceres is easier due to a weaker gravity & that Europa is extremely<br />deep within Jupiter's gravity well, but BOTH are worthy of robotic craft landings.<br /><br />Just because Europa may be more difficult is no justification for not attempting it.<br /><br />If JPL does it, then chances are it will succeed. I would love to see landers on 1 Ceres as well<br />as all four of the Galilean moons (Io is a real problem radiation wise) & Titan & Enceladus <br />& Iapetus, & Ariel & Titania & Oberon & Triton & Mercury, many more on Mars & <br />the Moon as well as Pluto, Charon & Eris.<br /><br />Not asking for much am I ???? <img src="/images/icons/crazy.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[DuhFly]

I vote for Ceres. At least for the first trip. Since radiation is low, humans could make the trip. And, since it has water, they can make fuel for the return trip. <br /><br />It could also serve as a refueling station for space crafts heading to the outer solar system. Or tanker type space crafts can be based there to refuel space crafts on their way to the outer solar system.

 

[docm]

A cheap robotic mission for Ceres first then use the lessons learned there to send a much larger mission to Europa. <div class="Discussion_UserSignature"> </div>

 

[3488]

True.<br /><br />When DAWN arrives, we will see for sure if it is worth a lander mission to 1 Ceres.<br /><br />IMO it is. If I had the influence, I would get a lander to both ASAP.<br /><br />I agree docm a 1 Ceres landing would be an excellent practice run for a Europa <br />mission (not to mention the surface images & other science).<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[j05h]

<i>> A cheap robotic mission for Ceres first then use the lessons learned there to send a much larger mission to Europa.</i><br /><br />That seems the most sensible path. My critique of starting a Europa lander is that it already happened and was cancelled (JIMO). Ceres seemed more acheivable, especially when compared side-by-side.<br /><br />j <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[j05h]

<i>> Just because Europa may be more difficult is no justification for not attempting it. </i><br /><br />JIMO was already attempted and canceled. It's not that it isn't worth it, but doesn't seem politically achievable. The chances of a private Europa lander would be even lower for now.<br /><br />Yes, ground truth throughout the Solar System is desirable, but unlikely baring huge technical and economic leaps. Then again "No guts, no galaxy". <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[dragon04]

<font color="yellow">A cheap robotic mission for Ceres first then use the lessons learned there to send a much larger mission to Europa</font><br /><br />Hand that man a cookie. That sounds like a great idea. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[docm]

I'll take it one step further; include a "dumb" mole. <br /><br />No mini-sub, just a nuclear heat generator in a Teflon coated can, ballast and enough instrumentation to gauge its depth & rate of descent. This might deliver some useful data to those working on Europa's mole. <br /><br />Call it a proof of concept. <div class="Discussion_UserSignature"> </div>

 

[mithridates]

I would go for Ceres because of the higher possibility of rousing the imagination of the average person with a destination that humans could (relatively) easily visit. In terms of looking for life, we have quite a bit going on not only with ground-based observatories but also with COROT and Kepler starting next year as well, so even if far away we should have no trouble finding enough locations that possibly carry life that we will be able to get past the idea that Earth is the only habitable location in the universe.<br />Not that I don't have an interest in Europa, but since the thread is based on choosing one, that's what I would go with.<br /><br />I wonder what sort of observations of Jupiter could be carried out with an orbiter around Ceres as well though:<br /><br />http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1+Ceres&orb=1<br /><br />Every 7 years or so the two seem to be somewhat close, about twice as close as Jupiter is to Earth. <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[3488]

Hi mithridates,<br /><br />Pretty impressive I would imagine. Jupiter at opposition from 1 Ceres.<br /><br />Try & find out if that will happen with DAWN from either 1 Ceres or 4 Vesta.<br /><br />Below: Mars Reconaissance Orbiter HiRISE camera got a nice image of Jupiter from Mars Orbit.<br /><br />Wednesday 10th January 2007.<br /><br />Jupiter was at oppostion as seen from Mars on that date.<br /><br />NASA / JPL.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

J0SH,<br />In full agreement!!!! (for quite a long time)<br /><br />Europa is more likely to host life (size matters) but is indeed a very difficult target (high radiation in deep grav wells).<br /><br />I would suggest, assuming Dawn detects a cryo-activity outlet, to land at such an outlet and proceed with bio analysis of the vented ice.<br />No need to drill in that case.<br />For Europa, the strategy would be similar excepted that:<br />* the location of fresh recent ice, with potential frozen fish in it, is less easy from orbit in the absence of cryo volcanoes;<br />* because of radiations you need to drill at least 1m, for any bio material would have been destroyed. Unless you have spotted a VERY recent water upsurge but so unlikely...<br />* the grav wells are far deeper as Andrew pointed out,<br />* a lander robot would have very little time to achieve its mission, because the radiations will burn it within a few weeks<br />* we need an orbiter first, before designing the lander: now the orbiter will arrive around Europa at best in the mid 2020s, whereas we will have a Ceres orbiter in 2015.<br />* at 5.2 AU, you have 0.037 Solar Constants, instead of 0.127 at Ceres (you need Solar Arrays four times smaller)<br />So Ceres would be far easier.<br /><br />The only con is that we do not know whether there is really really fresh ice on Ceres surface (<1 Myrs), whereas we know for Europa.<br /><br />I had even dreamed of a Ceres Sample Return mission. Why not designing it right now, and wait for Dawn's results to trigger the implementation phase?<br /><br />The basic exploration rule is "leave no stone unturned". So we need both a Ceres mission and a Europa mission. <br /><br />I am a little bit optimistic but to me a Ceres lander is at worst an M-class ESA mission or a Discovery-class NASA one.<br /><br />A Ceres Sample Return would be much more expensive, but a phase 0 can probably be afforded.<br /><br />Best regards.

 

[mithridates]

That's a nicer image than I would have thought possible. Looking at the orbit diagrams of Vesta, Dawn will be somewhat closer than the Earth to Jupiter during its time there but only about as close as Mars during closest approach. It'll be a bit below the main orbital plane though which might be interesting. And for Ceres...<br />nope, it'll be about as far as you can get from Jupiter during its time there. Closest approaches will be around Aug. 2012 and Aug. 2019.<br /><br />What would Jupiter look like at closest approach for a person on the surface of Ceres with a standard pair of binoculars I wonder? <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[mithridates]

Adding to that are the frequent eclipses of the Sun by Jupiter for an Europa mission, and being tidally locked with a period of 3.5 days would mean quite long periods of dark whereas on Ceres one day is about 9 hours, so batteries to last through the night would not have to be so large. Ceres also has little seasonal variation (axial tilt 4 degrees - comparing to the situation with the rovers on Mars now) and no dust storms to worry about either. <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[3488]

1 Ceres wpould prove to be the ideal proving ground for any extended lander program into<br />the outer solar system.<br /><br />A mithridates pointed out, Europa has frequent eclipses by Jupiter & has a long night. <br /><br />Not to mention the high radiation environment.<br /><br />1 Ceres has nights lasting approx 4 hours & 30 minutes.<br /><br />Solar power would work, but IMO RTGs would be far better as more science & higher <br />communication rates could be accomplished. Sunlight on average would be about <br />168 watts per square metre with the Sun at zenith, so to get the best for solar power, the lander<br />is limited to the equator.<br /><br />With RTGs, in theory nowhere would be off limits.<br /><br />Certainly, high resolution Pan Cams like on the MERs would be desirable, perhaps <br />with zoom capabilities to bring features on the horizon closer. <br /><br />A gas chromatograph to sample the extremely tenuous'atmosphere' & I would<br />like a seismometer, to see if the dwarf planet is internally active.<br /><br />Perhaps DAWN will discover ongoing activity, but I doubt it. I suspect there will be<br />huge cliffs & compressional features, when the interior cooled & the crust fractured above it.<br /><br />We'll see when DAWN arrives.<br /><br />thanks mithridates regarding DAWN & potential Jupiter observations from 1 Ceres orbit.<br /><br />I have not researched it as yet myself, but you have answered that.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

Hi Andrew,<br /><br />The point with RTGs are that they are so expensive...<br />If only we could get a cheaper version.<br /><br />Regards.

 

[h2ouniverse]

As far as Solar Power is concerned, there is on-going development for Low Illumination Low Temperature cells to work even at Saturn!<br />But 168 W/m2 is pretty high. Even classical AsGa technology would be OK.

 

[3488]

Hi Joel,<br /><br />I had heard of something like that, using small conical mirrors to concentrate<br />very weak sunlight onto photovoltaic cells.<br /><br />As for 1 Ceres, normal GaAs cells would be work, but my main concern is that, most power & time would <br />be used to charge batteries, rather than actually power the spacecraft, hence very <br />little science return, if any.<br /><br />With the MERs, it is not really a problem (dust storms permitting) because they have on<br />average a full 44% of the sunlight<br />available on Earth or roughly a full 581 watts per square metre with the Sun at zenith.<br /><br />I suppose with more energy efficient electronics, it may not be too bad in a few years<br />as far out as 1 Ceres. <br /><br />RTGs are a big expense & apparently (do not know if true) there are supply problems<br />with Plutonium (one of the excuses given for the cancellation of New Horizons 2).<br /><br />Yes I would like to see, solar power work for such a mission, but the craft will spend at<br />least half of its time during the 1 Ceres night.<br /><br />With RTGs perhaps night time observations could be carried out, ie seismological obs, thermal<br />obs of how the surrounding surface cools down after sunset & astronomical <br />observations, which will assist in the precise motions of 1 Ceres. <br /><br />Just my own thoughts.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[solarspot]

"AsGa technology"<br /><br />Just nitpicking, but I think you got that abbreviation the wrong way around. You're talking about Gallium Arsenate solar cells, right?<br /><br /><br />

 

[3488]

Yes that is it.<br /><br />Bog standard Gallium Arsenide.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

I think the charging issue can be compensated by larger arrays. LILT technology btw does not depend on concentrators, even if concentrators are added to further increase power.<br />Clearly, RTGs would make the mission pass from ESA-class M to a big L, or outside NASA Discovery class.<br />Regards.

 

[h2ouniverse]

Sorry <br />That's the way we call it there on that side of the Channel, AsGa for "Arseniure de Gallium".<br />Your Gallium Arsenide.<br />I use GaAs in English documents, but there at SDC, I was feeling like at home.<br /><br />