[X] My Assistant

[Guest_AlexBlackwell_*]

(3) There were a really astounding number of other differences -- genuine hardware differences -- between Mars Polar Lander and the MS 2001 Lander, which were lovingly listed by that gent (can't remember his name just now) who had a lengthy website up for a long time urging reuse of the MS 2001 Lander, as part of his evidence that it might not share MPL's failings. He's no longer on the Web, but I have copies of most of his stuff -- including that list of differences. Just give me time to find it on my CD-ROMs.

Yeah, I remember the website. It had some cool info. I seem to remember it was titled something like www.savethemarslander.com. Not that it really mattered, at least to me, but didn't the "gent" who organized the website turn out to be a Lockheed Martin engineer or something like that?

[djellison]

Wasn't it the same guy who then went on to argue the case for a Pluto mission as well - and infact, I think he may have popped in here once or twice as well ( but I can't remember his username )

Doug

[Guest_AlexBlackwell_*]

Wasn't it the same guy who then went on to argue the case for a Pluto mission as well - and infact, I think he may have popped in here once or twice as well ( but I can't remember his username )

I found out it was actually savethemarslander.org, which no longer exists. Are you sure the same guy was also behind www.plutomission.com and/or www.plutoportal.net?

[djellison]

Maybe it wasnt - I was sure there was a link there in some way - I do remember that old site being quite usefull though. Amazingly, there are still some interesting images at http://marsweb.jpl.nasa.gov/2001/lander/index.html including this..



Doug

[Guest_BruceMoomaw_*]

They're two different guys. "Pluto Portal" -- which really did play a major role in saving that mission -- was founded by undergrad college student Ted Nichols. I'm still in the process of tracking down my records on the "Save the 2001 Lander" site, but it was done by a different guy who was a full-fledged engineer.

[Guest_BruceMoomaw_*]

Okey-doke, I've found all my stored records on this, and am currently looking them over. I've also discovered the guy's name, which I'd forgotten -- and here is the original Space.com article on his effort: http://www.space.com/news/spaceagencies/ma...ers_000929.html .

The real shocker is that there is a "Harrison Quigley" on the net who is a committed Scientologist! I haven't been able to confirm that they're the same guy, but there can't be that many Harrison Quigleys wandering around out there...

[Bob Shaw]

Okey-doke, I've found all my stored records on this, and am currently looking them over. I've also discovered the guy's name, which I'd forgotten -- and here is the original Space.com article on his effort: http://www.space.com/news/spaceagencies/ma...ers_000929.html .

The real shocker is that there is a "Harrison Quigley" on the net who is a committed Scient*l*gist! I haven't been able to confirm that they're the same guy, but there can't be that many Harrison Quigleys wandering around out there...

Bruce:

Surely not? I followed a few Google links and the Scient*l*gist appears to be some form of management consultant who applies Elron's wisdom to assist his many and varied customers. Er, yes.

You can tell he's really a, you know, by the last page of one of his several sites, where you find the phrase: 'REFUND POLICY: No refunds. All sales are final.' - sounds like a management consultant to me!

BTW, it's amazing who's picture you can find on the WWW! Can this one be used for the BBQ?

Bob Shaw

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[Guest_BruceMoomaw_*]

Where the hell did they get THAT?

[Guest_BruceMoomaw_*]

Ahem. Anyway, here's the first part of Quigley's notes on the differences between the 1998 and 2001 landers. (The rest I have only on paper and will therefore have to type in, which will take a while.)

"In mid-1996, scientists announced the discovery of possible evidence for fossil life in a Martian meteorite found in Antarctica (ALH840001). This discovery led to all kinds of suggestions for speeding up the exploration of Mars. Most notable was the talk of moving the sample return mission (then generally presumed to happen in 2005) up to 2003. Around the same time, Dr. Steve Squyres of Cornell University had teamed with JPL and Lockheed Martin Astronautics to propose a Discovery mission to Mars that would derive a lander from the MSP'98 lander that would simply deliver a rover to the Martian surface and act as a communication relay for it. The Athena rover would conduct its own scientific investigation and cache samples for pickup by a later sample return mission. The Athena proposal was not selected for that round of Discovery. However, in December 1996, a request for an augmentation to the Mars budget was made; and JPL directed the Mars Surveyor Program prime contractor, Lockheed Martin -- who had just finished CDR of the MSP'98 orbiter and lander and had been in the formulation stage of a 2001 aerocapture orbiter for nearly a year -- to start planning a lander for the 2001 launch opportunity.

"The original 2001 Mars lander mission was very similar to the proposed Athena Discovery mission, except that in this scenario, the lander was not kept alive as a communication link to Earth. It simply delivered the rover and was allowed to die the first night. This made it relatively easy to adapt the MSP'98 lander (Mars Polar Lander, MPL) design because the hardware used to keep the lander alive on the surface (solar arrays, insulation, etc.) could be eliminated to provide the extra 20kg or so of payload capability needed by the large rover.

"In January 1997, the HEDS enterprise of NASA contacted JPL and requested that the 2001 Mars lander mission change to keep the lander alive so that they could fly some experiments to start preparing for a human mission to Mars. At this point, the mission changed substantially from the heritage MPL design. Some of the HEDS payloads needed to operate through the night. But whereas the MPL had been designed for a polar site, where there was some sun 24 hours a day, the '01 Mars lander was going to an equatorial site, and the original MPL design could not handle the long nights without sun and power the payloads at the same time. As a result, the '01 lander power system was completely redesigned from '98. New lightweight, flexible solar arrays provided over 3 times the battery capacity and nearly twice the solar collection area for less mass than the '98 lander power system.

"Also early in 1997, it was decided that because of the large volume needed by the rover and extra payloads, the '01 lander aeroshell would be larger than the '98 aeroshell. The Pathfinder aeroshell, at 2.65 m diameter, was as large as could be launched on a Delta 7425 with a 9.5 foot fairing, and so that size was chosen. The large diameter was also needed for the '01 orbiter, which at the time was designed as an aerocapture orbiter, and so made as much volume available as possible to squeeze an orbiter into an aeroshell. (It's interesting to note that the reason the '01 orbiter was aerocapture-type was that the program had been told that they would never get a 7925 launch vehicle, so the only way to get an orbiter into orbit in the '01 opportunity with its high arrival V-infinity was with aerocapture). Also, to make packaging easier, both spacecraft were mounted upright inside the aeroshell like Viking, as opposed to upside-down like Pathfinder and MPL.

"Other performance enhancements were also going to be needed to fly what was now 66 kg of payload to the surface -- nearly three times the MPL payload mass. Throttle valves were proposed as a way to enhance the propulsion system. A change to the Viking ratio for the disk gap band parachute was decided on to increase parachute performance. High-efficiency DC/DC converters, High Density Interconnect (HDI) switch cards, and high efficiency SSPA's were also being studied as ways to milk more performance out of the system. In late 1997, the decision was made to eliminate the throttle valves and the high efficiency SSPA, both because of funding and a belief by the program that they both weren't necessary and were an additional development risk for an '01 launch on a program which already had several. Then in December of 1997, the potential of the HEDS financial support going away threatened the lander design, and for a month or two, two options were carried: the 'rover-delivery-only' lander and the 'long life' lander.

"The money was finally made available to keep the live lander program, and the design effort continued. The lightweight solar arrays, the lithium ion batteries, the high efficiency DC/DC converters, the larger aeroshell and the larger parachute all survived the preliminary design phase, and continued on -- making the '01 Mars lander not only an important space science mission but also an important technology demonstration mission. However, the rover had continued to grow, and by April 1998 it was clear that more payload mass was going to be needed. The rover grew from its original 45 kg allocation to over 70 kg. The entire payload suite was now over 100 kg. To accommodate this, the lander was redesigned to include a propulsion system on the cruise stage so that the lander tanks could be used entirely for EDL. The lander itself was also reconfigured (it now had four legs) to accommodate the larger rover and the additional thrusters needed to decelerate the extra mass. Because of all these growths, the cost had also continued to grow, particularly because the lander now needed a 7925 launch vehicle.

"In June 1998, NASA commissioned Tony Spear (Mars Pathfinder program manager) and a board of others to evaluate the '01 program and make recommendations on how to reduce cost on the '01 program. The Spear board felt that the '01 program was trying to include everything but the kitchen sink (remember the high payload mass fraction), and recommended dramatic descopes. First, they recommended that NASA spend the money on a bigger rocket for the '01 orbiter rather than on the aerocapture development. In hindsight, this may have been one of the biggest mistakes NASA made. In fact, the Young board would later suggest that the acceptable risks to take were just these sorts of developments that furthered technology. Instead, NASA chose to force the design of the '98 orbiter (in no small part due to the fact that the MSP'98 program manager was on the Tony Spear board) onto the '01 program. It required changing the tank sizes, as well as reconfiguring hardware to accommodate the GRS instrument. The spacecraft was now flying in a different manner than the original MSP'98 design did.

"The other major recommendation of the Spear board was that the rover design was not mature enough to make the '01 launch without more mass growth, and such a risk was too great. So in July 1998, NASA removed the Athena rover and chose to fly a copy of the Sojourner rover. The '01 lander design reverted to what it had been prior to the April re-baseline, with the one notable exception that it was now mounted upside down in the aeroshell, partly because that's what the Spear board was familiar with (Pathfinder and MPL). They considered forcing other changes as well, using either Ni-Hydrogen (MPL) or Silver-Zinc (Pathfinder) batteries. It is difficult for someone to come from outside a program and accept the different requirements of the different mission (different environments, different payloads. It is a trait all engineers are guilty of to one degree or another; they all think their latest design is the end-all design. You can't blame them, they are all that way; you just have to learn to take it with a grain of salt.

"The Athena rover was slipped to the '03/05 program. The aerocapture orbiter became the domain of the French Space Agency, who with significant assistance and some technology transfer from NASA, embarked upon a crash program to 'catch up' on aerocapture for use on the 2005 Mars Sample Return Earth Return Vehicle.

"The '01 program had PDR in October 1998; and despite what appeared to be low margins, the experience of the JPL/Lockheed Martin team over four spacecraft in as many years coming in at or under the limits convinced the teams they were OK.

"And indeed, they were. As CDR came and went in April of 1999, the hardware coming in was coming in just as expected, at or within the limits. Only the lander cruise array was changed to include multi-junction solar cells, because of propulsion cruise heater requirements creep and a desire for the ability to transmit at all times. The MPL -- designed for 4 hours transmit, 5 hours receive -- was performing well enough that they could transmit all the time if they wanted to. However, because of the greater thermal extremes on the surface at the equator, the '01 lander was better insulated than MPL. That plus differences in the cruise stage design meant that, in order to transmit all the time during inner cruise (just after launch), they needed a bigger radiator for the SSPA, which meant a lot more heater power during outer cruise to keep it warm. The change was made and the lander fabrication continued.

"In September 1999, the loss of the MCO prompted, among other things, two major impacts to the '01 lander. The first was -- because the '98 orbiter was the 1st backup comm link for the lander ('01 was prime, '98 was 1st backup, and MGS was 2nd backup) -- the project studied ways to provide more communications backup. A change about a year before in the '01 lander UHF system made it impossible to command via MGS; it could only relay data back to Earth through MGS. It was decided to add a direct-from-Earth command link to the lander (in this case, adding a slice to the UHF transceiver to include S-band uplink capability). The other major change was that, during a scrub of the MPL prior to December but after the MCO loss, it was discovered that the descent thrusters needed much more heating than originally planned for. Just to make sure enough power was available, a scab-on solar array was added to the '01 lander.

"On November 30, the MSP 2001 lander was powered on for the first time. On December 1, 1999, testing commenced on the 2001 lander.

"Then, on December 3, 1999, MPL, launched 11 months earlier, turned its antenna away from Earth to line up for entry and jettison its cruise stage and was never heard from (for sure) again. Within days, people from everywhere, without first taking the time to closely examine the '01 program, suggested canceling the '01 program. The '01 project decided the direct-to-Earth link needed to be added for downlink as well, particularly during EDL. Meanwhile, by Christmas, the '01 lander had over a hundred hours of power-on testing and had been performing much more smoothly than any of the previous four spacecraft recently built and tested by the JPL/LMA teams (due mainly because of the experience gained during the previous programs."
_________________________

To be continued...

[Guest_BruceMoomaw_*]

Here are Quigley's remaining notes on the differences between the two landers:

"You'll be surprised to learn just how different the 2001 Lander is from its predecessor...In fact, over 90% of the drawings were re-released. That means over 90% of the Lander was modified or new. If you look at the details of the program, it is not all that surprising...The '01 program had completely different management -- including a flight system manager from the Cassini program, who was much less used to the FBC approach. Even more importantly, the mission was different. The '01 Lander was to fly three times the payload to Mars that MPL flew...Somewhre, engineers had to find the capability to fly 40 kg more payload on a spacecraft that, at touchdown, weighed between 350 and 400 kg dry. Where did they get the extra performance?

"There were three areas where they got the extra performance. The first was in advancing technology. The '01 Lander has lightweight flexible solar arrays and lithium ion batteries, which produced a power system that had two to three times the energy capacity of the '98 Lander at less total mass. The second area was eliminating hardware. With three orbiters planned (MGS, MOC, and the '01 Orbiter), it was decided early in the program to eliminate the X-band transmitter that would return science data directly to Earth, in favor of a redundant UHF ratio that would return science data to the three orbiters. Because the X-band transmitter couldn't provide the required science data volume and couldn't operate very long under the temperature extremes on the surface, it was eliminated. (It was reinserted in late 1999, because of the MCO failure and the fact that the '01 Orbiter wasn't there yet.)

"The third area where engineers got more payload mass was simply milking more peformance out of the entry-descent-landing system. A change in the parachute back to the Viking disk-gap-band ratio and a bigger aeroshell, plus a higher thruster duty cycle and a lower landing site altitude, all contributed to more landed payload mass. When it was done, the Lander could carry three times the payload to the surface as the '98 Lander. The result was a system that, while inheriting greatly from the lessons and experience of the MPL design (as well as Viking), didn't use all that much of it.

"While the differences extend through every subsystem on the Lander, the only ones that really have immediate bearing [on the cause of MPL's failure] are the differences in the Entry, Descent and Landing systems...From the moment the Lander slewed to the entry attitude, the mission was different from MPL. The pyro devices that separate the cruise ring were different, as was the software that fired them. The aeroshell was larger than the MPL aeroshell; in fact, it was the same size as that of Mars Pathfinder. The flight control in the hypersonic phase was completely new. While MPL simply executed a 'roll hold' to keep it from spinning during its ballistic entry, the '01 Lander incorporated an offset center of gravity to generate lift. The thrusters (same thrust levels, but obviously different placement than MPL's) then rolled the craft around to control the lift vector. This had the effect of taking out errors and reducing the landing ellipse length by a factor of 10 or more over MPL...

"The parachute was also modified from MPL. MPL used the Pathfinder chute; but the '01 Lander used a more Viking-like chute to get more drag and slow the craft down more. The separation system between the Lander and the backshell was also completely different. Rather than four sets of bipod struts, there were three, with the obvious differences in pyros, firing sequences, and actual mechanical load design.

"In fact, only once the terminal descent engines were ignited was there any real similarity to MPL. The terminal descent propulsion system was similar (12 pulse-mode engines), although the details of the system were different and many of the parts were different. The control logic had some changes made to it as well, mainly because of the different mass properties and flight characteristics of the different-sized vehicle...So it turns out that the '01 Lander was more unlike MPL than it was like it in the EDL phase."

[Bob Shaw]

Where the hell did they get THAT?

Bruce:

Google 'Bruce Moomaw', 'Sacramento' and... ...(wait for it!)... 'L5 Society'!

You ol' romantic, you!

Bob Shaw

[Guest_BruceMoomaw_*]

I take pride in having personally, through 17 years of unrelenting work, turned the Sacramento L-5 Society away from its evil pro-manned spaceflight ways into an innocent discussion group regarding space travel in general. Believe me, it took a lot of red-faced screaming to do that. I suppose that photo is their revenge.