Is there any chance that Archaea come from Mars and Bacteria come from Earth? Is it known why Archaea and Bacteria split into two different kingdoms?
The other thing I was thinking about is that it would be a good idea to put a few scientific instruments on the fetch rover.
None whatsoever.While being quite different, they share an enormous amount of common machinery, to the point they absolutely have to have a universal common ancestor.
Quote from: speedevil on 06/14/2018 12:23 amNone whatsoever.While being quite different, they share an enormous amount of common machinery, to the point they absolutely have to have a universal common ancestor.So a Martian organism that evolved independently is not going to share common machinery with a Bacteria or an Archaea. Even if they all look the same under a microscope, once you start applying modern biochemistry you could be absolutely sure that you could tell Martian life from Earth life. It seems to me that if you can distinguish Bacteria from Archaea, then it ought to be easy to distinguish Earth life from Martian. As long as they evolved independently. If panspermia works, then Bacteria, Archaea and Martians will all share a common ancestor and have some common machinery. That would make it harder to distinguish Martian life from contamination from Earth. All of the above has implications for planetary protection. I think NASA worries too much about it.
Not if they both had a common ancestry. Earth and Mars are consistently sharing material, it didn’t suddenly stop.
Even the best case scenarios for MSR look like budget busters, so I'd be pretty surprised if the fetch rover had much of a dedicated science payload.
Quote from: hop on 06/14/2018 02:06 amEven the best case scenarios for MSR look like budget busters, so I'd be pretty surprised if the fetch rover had much of a dedicated science payload.I think that an APXS, an IR spectrometer and a microscopic imager are all small and cheap as instruments go. I agree that budget pressures will be severe, but the fetch rover will have years of useful life left after it has completed its primary mission. There is also a case that adding anything that isn't strictly needed for sample return could open Pandora's box and lead to a cost explosion as more stuff is added. The is a case for being very focused.
The fetch rover will be going over the same territory as the rover that left the samples. Might not be worth the money having instruments other than cameras to do a second look. The fetch rover will need cameras to navigate and pickup sample containers. Comparing with previous pictures to see how things have changed would be useful.
There are strong pressures to keep the fetch rover as simple as possible. First, the rover will need to be very light; I believe that the current target is 125kg (Oppy is 180kg and ExoMars rover is ~425kg). There will be a lot of pressure to keep it as simple as possible, which still requires a great deal of autonomy as well as a system to pick up the sample tubes and place them in a storage container. Replicating the MER arm instruments would add a lot of complexity to the sample arm headAny science instruments add complexity (as well as mass) so I'm betting that instruments will be kept off. That said having the rover simply visit locations and image them with its cameras would still provide valuable scientific observations and ground truth for orbital observations.Also, the highly capable Mars 2020 rover likely will have 10 years on its own to explore the region. The fetch rover could be sent in a different direction to visit different locals.
Will this total mission be the heaviest payload ever sent to Mars?
Quote from: Star One on 06/15/2018 11:58 amWill this total mission be the heaviest payload ever sent to Mars?So, from the 2010 mission concept study:Lander mass = 554 kgSample return rocket mass = 300 kgFetch rover mass = 157 kg(All these masses include the reserve. Without reserve the rover is 110 kg)I assume that you have to add those together to get the total landed mass of 1011 kg. That compares to 899 kg for Curiosity. So yes, it will be the heaviest payload ever sent to Mars.They plan to use the same landing system as for MSL. Skycrane capability is quoted at 1050 kg, so they are getting close to the limits of the Skycrane.Total cost was estimated at 2.5bn(2015 $)
All of which is OBE. We had that study done for the decadal survey. There's new work being conducted now and some of the tech decisions have been made or are about to be made.
Looking at a fairly recent MEPAG presentation I notice that the sample return capsule has gone from 5 kg to 12 kg , <snip> 12 kg seems like a lot of packaging for under 1 kg of sample<snip>
return rocket (NASA calls this the MAV) has switched from a proven solid to some kind of novel hybrid solid design.
Looking at a fairly recent MEPAG presentation I notice that the sample return capsule has gone from 5 kg to 12 kg , and the return rocket (NASA calls this the MAV) has switched from a proven solid to some kind of novel hybrid solid design. 12 kg seems like a lot of packaging for under 1 kg of sample, and I don't love the idea of developing a new rocket motor technology for the sample return mission. I'm guessing the growing mass of the sample capsule has forced this switch?
I believe that a big driver is finding a fuel that could take long periods of cold temperatures.