Revelation From United States of America, joined Feb 2005, 10481 posts, RR: 20 Posted (4 years 7 months 1 week 6 days 21 hours ago) and read 2722 times:
Quote:
Concerns have been raised about how to pay for the project's escalating costs and whether engineers can ready the rover in time for a safe launch next fall. NASA has poured $1.5 billion into the project, but the final price tag is expected to be close to $2 billion.
So much for quicker better cheaper, or whatever that saying was...
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In recent public meetings, McCuistion noted that the Mars Science Lab would likely cause "financial collateral damage" to other space missions to pay for cost overruns.
Last week, James Green, who heads NASA's planetary science division, said possible funding sources could come from the Juno Jupiter mission and the lunar Grail and Ladee projects.
A group of scientists that advises NASA on planetary missions called this week for an outside investigation into the Mars Science Lab's financial troubles. The scientists noted that the pricey project was a "poor model for future missions."
The article doesn't say why they needed to upsize this rover to the size of a SUV.
There was some overlap (Mars Pathfinder was FBC) but the Mars missions were seperated from Discovery/FBC after the dual fiascoes of Mars Polar Lander and Mars Climate Orbiter in 1999. NASA now basically plans one flagship mission and one low-cost Mars mission (called Mars Scout) alternating between every 26-month launch opportunity. Mars Reconnaissance Orbiter (2005) was the last flagship. Mars Phoenix (2007) was the last Scout. MSL (2009) is the next flagship. The MAVEN orbiter (2013) is the next Scout. Mars Scout missed the 2011 launch opportunity after a delay caused by conflict of interest in the mission selection committee.
Quoting Revelation (Thread starter): The article doesn't say why they needed to upsize this rover to the size of a SUV.
MERs Spirit and Opportunity are essentially at the maximum size capable of being landed using the airbag method (and it was a real struggle to make it work for them). Anything more ambituous (which is the next logical step) needs a bigger lander/rover. If you want to travel farther, work longer on the surface, land somewhere other than near the equator, and perform more science, you need more power, which means an RTG, which means a heavier, bigger spacecraft.
Revelation From United States of America, joined Feb 2005, 10481 posts, RR: 20 Reply 2, posted (4 years 7 months 1 week 6 days 18 hours ago) and read 2700 times:
Revelation From United States of America, joined Feb 2005, 10481 posts, RR: 20 Reply 3, posted (4 years 7 months 1 week 6 days 18 hours ago) and read 2698 times:
Quoting Thorny (Reply 1): Anything more ambituous (which is the next logical step) needs a bigger lander/rover.
There is a point of diminishing returns in going larger.
It's the old pack of wolves versus a single lion problem.
The Wiki page says 10 main instruments are proposed for the rover.
One wonders if things wouldn't have been faster/better/cheaper if we had a few different rovers with different sets of instruments rather than one large lander with 10 instruments.
It seems NASA is stressing out trying to hit the launch window and not cannibalize the budget of other programs to pay for the rover.
One nice thing about the previous project was redundancy: if one failed, there always was the other one. We won't have that with the next rover, it seems.
Wait until you see the landing method! Sweating bullets will be an understatement.
Quoting Revelation (Reply 3): There is a point of diminishing returns in going larger.
The same is true with staying with small, solar-powered rovers, though I would have liked to have seen an MER 3 and 4 launched in 2005 or 07.
Quoting Revelation (Reply 3): One wonders if things wouldn't have been faster/better/cheaper if we had a few different rovers with different sets of instruments rather than one large lander with 10 instruments.
The problem is solar power too severely limits what the Athena-class rovers (Spirit and Opportuntity) can do. Only a small fraction of the time of the Athenas is actually spent doing science. With MSL, that figure will be in the 90% range. It won't have to shut down for the night. It won't have to spend half of the day recharging its batteries. It won't have to go into sleep mode over the winter, when the sunlight is too dim and short-lived to do travel or experiment. It won't be stuck within a few degrees of the equator because of the need to have direct sunlight on solar panels. It won't have to worry about dust accumulation on the solar panels cutting down solar power (what was expected to be the killer of the Athenas.)
And some of MSL's instruments require more power than solar can provide.
There is also the problem of saturation of the Deep Space Network. Its a lot easier to communicate and control one rover than it is 3 or 4. Spirit and Opportunity got around that by landing on opposite sides of Mars, so that only one was in contact with Earth at any given time. But when you start landing fleets of Rovers, you need to add more antenna dishes on Earth, driving up the cost.
Revelation From United States of America, joined Feb 2005, 10481 posts, RR: 20 Reply 5, posted (4 years 7 months 1 week 6 days 16 hours ago) and read 2662 times:
Quoting Thorny (Reply 4): The same is true with staying with small, solar-powered rovers, though I would have liked to have seen an MER 3 and 4 launched in 2005 or 07.
Yes, that would have been cool.
Quoting Thorny (Reply 4): The problem is solar power too severely limits what the Athena-class rovers (Spirit and Opportuntity) can do. Only a small fraction of the time of the Athenas is actually spent doing science. With MSL, that figure will be in the 90% range. It won't have to shut down for the night. It won't have to spend half of the day recharging its batteries. It won't have to go into sleep mode over the winter, when the sunlight is too dim and short-lived to do travel or experiment. It won't be stuck within a few degrees of the equator because of the need to have direct sunlight on solar panels. It won't have to worry about dust accumulation on the solar panels cutting down solar power (what was expected to be the killer of the Athenas.)
And some of MSL's instruments require more power than solar can provide.
There is also the problem of saturation of the Deep Space Network. Its a lot easier to communicate and control one rover than it is 3 or 4. Spirit and Opportunity got around that by landing on opposite sides of Mars, so that only one was in contact with Earth at any given time. But when you start landing fleets of Rovers, you need to add more antenna dishes on Earth, driving up the cost.
All very good points.
I wonder if we'll see an animation of the proposed landing sequence soon?
Also wondering how long the rover will be expected to last. The Wiki page says the power source is designed for a minimum of 14 years, but is that how long the whole project is supposed to last?
Nomadd22 From United States of America, joined Feb 2008, 1564 posts, RR: 0 Reply 6, posted (4 years 7 months 1 week 6 days 15 hours ago) and read 2653 times:
The MSL shouldn't have to worry about spending six months stuck in a patch of sand or steering around every rock on the ground. Going to a new site a few miles away is a major undertaking for the little guys, but should be much easier for the new kid.
I'm not sure if the MSL has a battery for a buffer or it'll just stop when the power gets too low to drive the wheels. I wouldn't take the Wiki article too seriously. The halflife of the plutonium is almost ninety years and the lifespan of RTGs has always been limited by the thermocouples deteriorating. The new models are supposed to be greatly improved over past ones like the Voyagers use, and they're still going after 34 years.
The "90 day" MERs have made a joke out of lifespan estimates. If the MSL lasts as long as they have it'll be pretty impressive. It should be able to get fifty times as much science done as an MER type rover. The main advantage of more, smaller rovers would be covering more areas of the planet.
I miss Pathfinder. I won a bet when I predicted the rover/ lander link would quit for a day or so after it landed because of temperature differences between the radios.
Thorny From , joined Dec 1969, posts, RR: Reply 7, posted (4 years 7 months 1 week 6 days 14 hours ago) and read 2647 times:
Quoting Revelation (Reply 5): Also wondering how long the rover will be expected to last. The Wiki page says the power source is designed for a minimum of 14 years, but is that how long the whole project is supposed to last?
Something else will probably break before the RTG fades too much. Viking 1 lasted 6 1/2 years on its RTG before it was accidentally killed.
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