Yes - they are very very expensive, very very efficient cells - but - they only generate roughly 140 watts at any one time.

The 600 - 800 values are watt-HOURS....i.e. the equiv of 100 watts for 8 hours. It's a cumulative total ammount of power generated in an entire sol.

Given 10 hours of sunlight - a 125 watt array would generate 1250 Watts in a day - ignoring the angle of incidence.

Doug

Hell yes. Just for fun

Doug

I'm REALLY looking forward to the Mars imax movie - Dan Maas is working on it - and we KNOW how amazing his stuff is. If it's 3d - we'll have full 3d martian terrain based on the imagery from the rovers.

Doug

Using orbiter I just managed an aero-capture It would rip the real MRO to pieces, but an altitude of about 40km sees me in a fairly eliptical orbit, and a altitude of 35km sees a fairly good orbit that only requries a few days of aerobraking And you get to keep 95% of your fuel

Doug

I'd say New Horizon's launch speed is about as fast as you can get reasonably (something like 11 - 12km/sec if my maths are right ) - add on perhaps the delta-v of ion propulsion of another 1 or 2 km/sec and that's about all you can get. That's why fly-bys are used to slingshot trajectories. Casini, Galileo, New Horizons, Rosetta, Stardust, Messenger etc - all getting Delta-V for free with flybys.

Doug

I guess we'll see with the next update at JPL - bad uplink perhaps - low priority imagery - who knows.

Doug

The centaur will be in a solar orbit that just about touches the earths orbit at it's low point, and just about touches mars's orbit at another point - 1 x 1.5 AU roughly.

Someone has written a very accurate MRO for Orbiter - and it's about 10.9km/sec immediately after launch, which slows to about 3.8km/sec after a couple of weeks - but it maintains that sort of speed for much of the cruise - it's all very variable though as it's hard to pick a reference point in space ( at least, in Orbiter it is )

From far out - approach to mars is about 4.5km/s - the speed will vary a lot really

Doug

MARCI will do observations of the Moon at some point - and HiRISE will do I THINK Moon + Star focus tests. Not sure of CTX, it may do the same.

Only one post-aerobraking deployment was mentioned, and that was SHARAD

Doug

Doug

I gave in - Amazon.co.uk told me delivery of this long awaited title would take a few weeks more and so I ended up with a problem - meeting Steve in only 3 weeks, and no chance to have read his book yet! I found an online retailer who sold an E-version of the book. Still got hard-copies on order, but at least I now had a chance to read it in plenty of time.

The bottom line - this is the book you've been waiting for. We all know where the rovers came from, where they landed, what they've seen. We all knew what happened to the Titanic - but millions flocked to the cinema to see HOW it happened.

'Roving Mars' is in three main parts - the struggle to get a mission at all, the struggle to get a mission to the launch pad - and the struggle of running the mission once on the surface. If that sounds like a lot of struggling, then that's because it was. From the earliest Pancam design ( a bush-broom like camera designed for the OLD Pathfinder multi-lander design ) that was turned down, thru to the near cancellation of MER on several occasions - even I had no idea just how much of a struggle it was to get these things off the ground. It is an almost a tragic vein combined with the nature of competitively won contracts to fly good instrumentation culminating in the fight to fly that make the first part of Roving mars without doubt the most revealing. Being turned down twice, before having a mission cancelled, and then having to start the fight all over again after the '01 failures, Steve just started again, gathered a good team, good plans, good designs and made sure that there was no option but to pick his new mission - the one that we see on the surface of mars today - and that we have two of them was as much a surprise to Steve as it was to anybody else.

Once selected - it's clear things were hardly a cake-walk. At post landing press conferences, Pete Theisinger, Steve Squyres, Ed Weiler and Firouz Naderi looked to be one big happy family, but rest assured, it was not always that way. The hunt for used pyro-bolts to prove the health of the vehicle is an almost comic tale

Then the landings, the thrill of those first Pancam images, and even then the struggle didnt stop - fighting to get that compromise between science HERE, and making progress to hopefully do science THERE - but the origins of the decisions that were taken are a great insight - with the narrative taking the form of a diary, much like that of his recent updates at the Athena website, but with more personal details, who, how and why the decisions were made.

Of course - for the most technically minded among us - even a transcript of SOWG meetings and complete uplink sequences wouldn’t suffice. Steve has managed to go as technical as he probably could without alienating those who want to read the story of MER without needing a degree in the subject.

It closes with one fitting touch - a collection of the names of all who were involved in every stage of the mission. On my e-version of this book - this list runs from page 615 to 755 - about 3900 names, a fitting reminder of the scale of what they achieved.

If you've logged on to the JPL website - seen a raw image and for that brief second gone "wow" - then find out why, and read this.

Review Score out of Six

Doug Ellison
Unmannedspaceflight.com
Buy Roving Mars at Amazon.com

Upcoming reviews include 'Mapping Mars', 'Full Moon', 'A Travellers Guide to Mars', 'Sojourner', 'Visions of Mars' and others

"When will the fun EVER stop


.. am I missing an eye brow"



Doug

It's a problem with the JPL server that feeds out to the Exploratorium - and will be sorted when someone can attend to it.


Doug

"is there *any* chance that we might get the original (uncompressed) versions ?"

Nope. There used to be leaks in the workbook - but they've all been fixed.

Doug

Strange crack in the terrain -

http://marsrovers.jpl.nasa.gov/gallery/all...B1P1700L0M1.JPG

Doug

They've already got 2:1 compression there - and they can always nest levels of detail - full res for the middle 4000 pixels, 2x2 binned thereafter etc etc

Doug

40,000 height x ( 20,000 Red + 4000 B/G + 4000 NIR ) = 1,120,000,000 pixels

12 bits, but 2:1 compression - a total of 6,720,000,000 Bits of data in a full HiRISE image. That's 6,720 Mbits

Now - at the lowest rate quoted of 0.288 Mb/sec - thats a total of 23,333 seconds - or 6.48 hours of transmission

At the highest quoted figure of 5.8 mb/sec - thats 1158 seconds or 19 minutes.

But obviously - HiIRSE is only one instrument - and MARCI and CTX will also be generating big data sets of imaging - and there's other instruments as well of course - all generating lots of data - especially CRISM - a LOT of data there.

So given perhaps a 1:7 contention ratio in terms of data budget - those figures of 0.3 hrs to 6.4 hrs could turn to 2.1 hrs and 44hrs

Doug

Sounded like serving to me Surveying makes sense, but only if it was Mars Global Surveyor

Doug

My office mate and I were taking bets on what the PAO voice over chap (Greg Diller?) would say at lift off - my guess was "Lift-off of the Atlas V rocket with the Mars Reconnaissance Orbiter - bringing us a closer view of the Red Planet" - or something like that...

but actually - what he said was just so pointless - all bets were cancelled
"And liftoff of the Atlas V rocket with MRO serving for the deepest insights into the mysterious evolution of mars"

Que?

Doug

Initial parking orbit is good - at last we're off the ground

During ascent I suddenly thought "woh, if this doesnt work - MSL is going to suffer a lot" - and got rather nervous

Not out of the woods yet- another centaur burn to go - and actually, I was suprised to hear that the centaur put the parking orbit perigee about 6 nm off target - that's a lot. Doesnt really matter that much I'd have though - it IS only a parking orbit after all, and it'll probabyl be made up on the second burn

Doug

I think almost all the ones we've seen would be visible in MOC imagery to be honest - they've all been 5m+ at LEAST on the ground - growing to be larger up above the gorund where we cant see it against the atmosphere so clearly

Doug

Back in with a brush and made it filthy? I dont think so. The clean rat hole is before the dusty rat hole chronologically. Dust deposition makes a lot more sense to me

Doug

No - it's really <10% of the earth-moon distance.

Doug

Wow - I wonder if they'll use the ion engine all the way up to arrival - or if they'll coast in and then come to a near standstill with thrusters.

At this rate - they'll be there in another 10 days

Doug

Thats JUST how I imagined them to look - nice job

Doug

Yup

Doug