50 ms·

Three spacecraft heading to Mars this summer

78 points by Hooke 6y ago

jcun4128 6y ago
Curious if they have to register/coordinate their intended flight path/orbits so they don't hit each other(probably very unlikely). Probably don't have onboard radar or something like that?
- choeger 6y ago
  > probably very unlikely Literally astronomically unlikely. If at all they might want to coordinate radio emissions.
  - onion2k 6y ago
    “Scientists have calculated that the chances of something so patently absurd actually existing are millions to one. But magicians have calculated that million-to-one chances crop up nine times out of ten.” Terry Pratchett in Mort
    - enkid 6y ago
      Sergeant Colon looked wretched. "Weeell, what if it's not a million-to-one chance?" he said. Nobby stared at him. "What d'you mean?" he said. "Well, all right, last desperate million-to-one chances always work, right, no problem, but...well, it's pretty wossname, specific. I mean, isn't it?" "You tell me," said Nobby. "What if it's just a thousand-to-one chance?" said Colon agonizedly. "What?" "Anyone ever heard of a thousand-to-one shot coming up?" Carrot looked up. "Don't be daft, Sergeant," he said. "No one ever saw a thousand-to-one chance come up. The odds against it are—" his lips moved—"millions to one." "Yeah. Millions," agreed Nobby. "So it'd only work if it's your actual million-to-one chance," said the sergeant. "I suppose that's right," said Nobby. "So 999,943-to-one, for example—" Colon began. Carrot shook his head. "Wouldn't have a hope. No one ever said, 'It's a 999,943-to-one chance but it just might work.'" - Guards! Guards!
choeger 6y ago
I am wondering why NASA only sends one rover. Considering the investments into development, planning, and control and the relatively low launch costs nowadays, I would think it logical to send two or more probes to mitigate the risk of catastrophic mistakes.
- rimliu 6y ago
  My understanding is that there is a dedicated team for each probe on the ground, so two rovers = two teams, twice the cost to support. Or am I wrong?
- adventured 6y ago
  The launch cost isn't low. They're using an Atlas V-541 from UAL. The program cost is equivalent to about 10% of NASA's annual budget, which is a lot. Mars and the rovers are just one corner of NASA's focus. It would cost a minimum of another $2 billion to duplicate this rover and mission, if you can find enough qualified people to task to it so as to not harm (by dilution) your ability to deliver on at least one of them. NASA's resources and talent pool are both very much limited.
- Wandfarbe 6y ago
  I'm pretty sure what makes that stuff so expensive is all the Quality Control for every single part. Its probably quite a linear cost vector they have.
  - C1sc0cat 6y ago
    The failure to a "repaired PCB" stands out just scrap the damaged one would make more sense.
    - rckoepke 6y ago
      Being that this was 1971, it was probably more straightforward to repair the botched installation/repair rather than do the whole PCB over from scratch. Features on PCB's were much simpler then, not to mention much larger. Their procedure was to test each component before installation only, in order to prevent any potential damage occurring during post-installation testing. So they evidently couldn't know to scrap it and replace the damaged one. After the Mariner 8 failure, they changed this testing policy to test PCB's/components again after components are installed on the PCB. "A diode intended to protect the system from transient voltages was thought to have been damaged during repairs/installation of the pitch amplifier's printed circuit board, something that would not have been detected through bench tests." - Wikipedia, but I'm having difficulty finding any original sources that validate or expand upon this. P.S. I think you may have responded to the wrong parent comment Edit: "N72-13963" was a report given to Congress in October 1971 on the failure of the Mariner 8 mission, I can't find that report but it may have more details if you're curious enough to track it down. Edit: I found a transcript of the report given to Congress, evidently in June of 1971: https://books.google.com/books?id=7FQVAAAAIAAJ https://books.google.com/books?id=7FQVAAAAIAAJ Dr. Low: The diode was external to this integrated circuit, mounted next to it. I don't have one with me, but the diode is another component about the same size. The integrated circuit which failed is known to be sensitive to electrical transients if it is not properly protected. And electrical transients large enough to damage an unprotected integrated circuit — caused, for example, by engine start, stage separation, et. cetera — are well within the specifications of the Atlas/Centaur vehicle and are clearly possible. Because of this, the integrated circuit was protected with Zener diodes which in effect were designed to act as "safety valves" to prevent potentially damaging electrical transients from reaching the integrated circuit itself. In accordance with standard practice in the Atlas/ Centaur vehicle — as well as in many others — these Zener diodes were checked individually prior to their installations, but were not tested thereafter. This practice of not testing protective devices after they are installed in a system is based upon the conclusion or design philosophy, which we are now reevaluating, that a test of a protective device after installation is not warranted where such a test could possibly damage the component that is being protected. Based upon the detailed consideration of the flight failure records and some very extensive "detective work" of personnel from the Lewis Research Center, which is responsible for the Centaur stage, and General Dynamics, the prime contractor, we developed the following hypothesis which we believe pinpoints the cause of the Mariner 8 failure : (1) One of the Zener diodes which was intended to protect the inte-grated circuit in the Centaur pitch rate gyro preamplifier was either installed improperly, was faulty itself, or failed at some time during assembly, vehicle checkout or powered flight. (2) An electrical transient sufficient to cause damage to the inte-grated circuit occurred some time after T-minus-40 minutes—when the autopilot performed properly--but before Centaur main engine start. (3) This damaged the integrated circuit affecting the gain of the autopilot pitch channel and causing the subsequent fixed engine position. Tests show that all subsequent mission events would be fully explained by this hypothesis. ... To prevent a recurrence of the problem which occured on Mariner 8, we required additional thermal and vibration tests on the Centaur state autopilot and new and special test procedures to ensure that the diodes protection the integrated circuits were properly installed and operative."
xupybd 6y ago
I really hate pay walled sites
- bklaasen 6y ago
  http://archive.is/7Xxfn http://archive.is/7Xxfn or, if you use Firefox https://bitbucket.org/magnolia1234/bypass-paywalls-firefox-clean/downloads/ https://bitbucket.org/magnolia1234/bypass-paywalls-firefox-c...
- iso1631 6y ago
  I hate software as a service, but people gotta pay the bills.
- Markoff 6y ago
  if you disable inline scripts in uBlock it loads OK, though there are missing pictures in bottom
merricksb 6y ago
https://archive.md/7Xxfn https://archive.md/7Xxfn
linuxftw 6y ago
Digital camera technology is leaps and bounds beyond the last rovers we sent. Hopefully we get top quality photos this time around.
- kevin_thibedeau 6y ago
  COTS sensors don't work well in a high radiation environment.
- monkeywork 6y ago
  isn't transmission bandwidth a bigger concern?
sixothree 6y ago
I know I'm a fuddy duddy, but I absolutely hate the naming scheme of our mars rovers - Curiosity and Perseverance are things you feel not things you do. I just hate it. Stop it NASA.
prando 6y ago
I am curious to know this - how do various nations/ space programs ensure that the objectives of their missions are significantly different that they don't end up repeating the work/ results of other missions (from other nations)? Do all space agencies work together to determine what the focus would be (I guess not, but it'd be cool, if it were like that)!

78 points by Hooke 6y ago

Curious if they have to register/coordinate their intended flight path/orbits so they don't hit each other(probably very unlikely). Probably don't have onboard radar or something like that?

choeger 6y ago
> probably very unlikely Literally astronomically unlikely. If at all they might want to coordinate radio emissions.
- onion2k 6y ago
  “Scientists have calculated that the chances of something so patently absurd actually existing are millions to one. But magicians have calculated that million-to-one chances crop up nine times out of ten.” Terry Pratchett in Mort
  - enkid 6y ago
    Sergeant Colon looked wretched. "Weeell, what if it's not a million-to-one chance?" he said. Nobby stared at him. "What d'you mean?" he said. "Well, all right, last desperate million-to-one chances always work, right, no problem, but...well, it's pretty wossname, specific. I mean, isn't it?" "You tell me," said Nobby. "What if it's just a thousand-to-one chance?" said Colon agonizedly. "What?" "Anyone ever heard of a thousand-to-one shot coming up?" Carrot looked up. "Don't be daft, Sergeant," he said. "No one ever saw a thousand-to-one chance come up. The odds against it are—" his lips moved—"millions to one." "Yeah. Millions," agreed Nobby. "So it'd only work if it's your actual million-to-one chance," said the sergeant. "I suppose that's right," said Nobby. "So 999,943-to-one, for example—" Colon began. Carrot shook his head. "Wouldn't have a hope. No one ever said, 'It's a 999,943-to-one chance but it just might work.'" - Guards! Guards!

choeger 6y ago

I am wondering why NASA only sends one rover. Considering the investments into development, planning, and control and the relatively low launch costs nowadays, I would think it logical to send two or more probes to mitigate the risk of catastrophic mistakes.

rimliu 6y ago
My understanding is that there is a dedicated team for each probe on the ground, so two rovers = two teams, twice the cost to support. Or am I wrong?
adventured 6y ago
The launch cost isn't low. They're using an Atlas V-541 from UAL. The program cost is equivalent to about 10% of NASA's annual budget, which is a lot. Mars and the rovers are just one corner of NASA's focus. It would cost a minimum of another $2 billion to duplicate this rover and mission, if you can find enough qualified people to task to it so as to not harm (by dilution) your ability to deliver on at least one of them. NASA's resources and talent pool are both very much limited.
Wandfarbe 6y ago
I'm pretty sure what makes that stuff so expensive is all the Quality Control for every single part. Its probably quite a linear cost vector they have.
- C1sc0cat 6y ago
  The failure to a "repaired PCB" stands out just scrap the damaged one would make more sense.
  - rckoepke 6y ago
    Being that this was 1971, it was probably more straightforward to repair the botched installation/repair rather than do the whole PCB over from scratch. Features on PCB's were much simpler then, not to mention much larger. Their procedure was to test each component before installation only, in order to prevent any potential damage occurring during post-installation testing. So they evidently couldn't know to scrap it and replace the damaged one. After the Mariner 8 failure, they changed this testing policy to test PCB's/components again after components are installed on the PCB. "A diode intended to protect the system from transient voltages was thought to have been damaged during repairs/installation of the pitch amplifier's printed circuit board, something that would not have been detected through bench tests." - Wikipedia, but I'm having difficulty finding any original sources that validate or expand upon this. P.S. I think you may have responded to the wrong parent comment Edit: "N72-13963" was a report given to Congress in October 1971 on the failure of the Mariner 8 mission, I can't find that report but it may have more details if you're curious enough to track it down. Edit: I found a transcript of the report given to Congress, evidently in June of 1971: https://books.google.com/books?id=7FQVAAAAIAAJ https://books.google.com/books?id=7FQVAAAAIAAJ Dr. Low: The diode was external to this integrated circuit, mounted next to it. I don't have one with me, but the diode is another component about the same size. The integrated circuit which failed is known to be sensitive to electrical transients if it is not properly protected. And electrical transients large enough to damage an unprotected integrated circuit — caused, for example, by engine start, stage separation, et. cetera — are well within the specifications of the Atlas/Centaur vehicle and are clearly possible. Because of this, the integrated circuit was protected with Zener diodes which in effect were designed to act as "safety valves" to prevent potentially damaging electrical transients from reaching the integrated circuit itself. In accordance with standard practice in the Atlas/ Centaur vehicle — as well as in many others — these Zener diodes were checked individually prior to their installations, but were not tested thereafter. This practice of not testing protective devices after they are installed in a system is based upon the conclusion or design philosophy, which we are now reevaluating, that a test of a protective device after installation is not warranted where such a test could possibly damage the component that is being protected. Based upon the detailed consideration of the flight failure records and some very extensive "detective work" of personnel from the Lewis Research Center, which is responsible for the Centaur stage, and General Dynamics, the prime contractor, we developed the following hypothesis which we believe pinpoints the cause of the Mariner 8 failure : (1) One of the Zener diodes which was intended to protect the inte-grated circuit in the Centaur pitch rate gyro preamplifier was either installed improperly, was faulty itself, or failed at some time during assembly, vehicle checkout or powered flight. (2) An electrical transient sufficient to cause damage to the inte-grated circuit occurred some time after T-minus-40 minutes—when the autopilot performed properly--but before Centaur main engine start. (3) This damaged the integrated circuit affecting the gain of the autopilot pitch channel and causing the subsequent fixed engine position. Tests show that all subsequent mission events would be fully explained by this hypothesis. ... To prevent a recurrence of the problem which occured on Mariner 8, we required additional thermal and vibration tests on the Centaur state autopilot and new and special test procedures to ensure that the diodes protection the integrated circuits were properly installed and operative."

xupybd 6y ago

I really hate pay walled sites

bklaasen 6y ago
http://archive.is/7Xxfn http://archive.is/7Xxfn or, if you use Firefox https://bitbucket.org/magnolia1234/bypass-paywalls-firefox-clean/downloads/ https://bitbucket.org/magnolia1234/bypass-paywalls-firefox-c...
iso1631 6y ago
I hate software as a service, but people gotta pay the bills.
Markoff 6y ago
if you disable inline scripts in uBlock it loads OK, though there are missing pictures in bottom

merricksb 6y ago

https://archive.md/7Xxfn https://archive.md/7Xxfn

linuxftw 6y ago

Digital camera technology is leaps and bounds beyond the last rovers we sent. Hopefully we get top quality photos this time around.

kevin_thibedeau 6y ago
COTS sensors don't work well in a high radiation environment.
monkeywork 6y ago
isn't transmission bandwidth a bigger concern?

sixothree 6y ago

I know I'm a fuddy duddy, but I absolutely hate the naming scheme of our mars rovers - Curiosity and Perseverance are things you feel not things you do. I just hate it. Stop it NASA.

prando 6y ago

I am curious to know this - how do various nations/ space programs ensure that the objectives of their missions are significantly different that they don't end up repeating the work/ results of other missions (from other nations)? Do all space agencies work together to determine what the focus would be (I guess not, but it'd be cool, if it were like that)!