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Why no section on the malfunctions?
Why no section on the malfunctions?
"One of the mission's four reaction wheels stopped working last year, and officials are worried another wheel could fail at any time." Kepler reaction wheel still problematic after mitigation
The article should briefly discuss whether this affected the satellite's ability to meet its pre-launch specifications and objectives?
- It is discussed briefly at the end of the Spacecraft history section. If you think it should be expanded, be bold and have a go! Rwessel (talk) 05:44, 9 May 2013 (UTC)
- My impression is that up to now, the failing wheel(s) have not had a notable impact on the mission (only a 10-day "safe mode" interruption); but if the second wheel should fail soon, Kepler may indeed fail the objective of determining the frequency of "second Earths" (and maybe not even find a single such planet). I don't know of any sources that discuss this, unfortunately, so can't add this to the article. --Roentgenium111 (talk) 13:36, 14 May 2013 (UTC)
I've changed the style of the '2013' section to give a more reflective overview of the RW problem instead of a more chronological approach that was before. Are people happy with this or do people think we should give more of a timeline of the failures and condition testing? Markh89 (talk) 20:29, 9 September 2013 (UTC)
- Had a thought, a way to both keep the the 2013 section concise and the detail of the activities undertaken to assess Kepler is to have a separate section on the RW problem. Unless anyone has any objections I'll try and put a new section in later this week when I have time, let me know your thoughts. Markh89 (talk) 20:06, 10 September 2013 (UTC)
- This has already been well discussed - if interested, you may wish to see the following archived discussion(s) => Talk:Kepler (spacecraft)/Archive 1#Requested move - there is other related discussions in the same archive as well - in any case - Enjoy! :) Drbogdan (talk) 02:09, 17 May 2013 (UTC)
NASA Kepler telescope helps identify 750 new planets outside our solar system
Headline-1: Planet bonanza: NASA announces discovery of 715 new worlds
"NASA says its Kepler telescope has discovered a bonanza of 715 planets outside our solar system, pushing the number of planets discovered in the galaxy to about 1,700."
Headline-2: ‘We Almost Doubled Just Today the Number of Planets Known to Humanity’
" "Our galaxy is looking far more crowded and hospitable. NASA on Wednesday confirmed a bonanza of 715 newly discovered planets outside our solar system." "Scientists using the planet-hunting Kepler telescope pushed the number of planets discovered in the galaxy to about 1,700. Twenty years ago, astronomers had not found any planets circling stars other than the ones revolving around our sun."
Headline-3: NASA Scientists Discover 715 New Planets — Data From Kepler Space Telescope Suggests 4 Alien Worlds Have Potential for Life
The Kepler space telescope was a marvelous instrument and performed great science however it has now failed due to the loss of 2 reaction wheels it requires 3 to function. As designed Kepler only had one backup wheel. It can no longer do the job it was intended to do. My question is why didn't the engineers that designed Kepler put in duel redundant reaction wheels for each axis? The reaction wheels are the weak link they only have a limited lifespan. putting 3 backup wheels for each axis would have extended Kepler's life for many many years to come. the cost compared to the overall cost of Kepler would have been negligible. It just seams to me the engineers would have taken lessons learned from hubble (gyroscopes and reaction wheels fail). in the past NASA has embraced the dual redundant theology why not now. — Preceding unsigned comment added by 126.96.36.199 (talk) 02:10, 7 March 2014 (UTC)
- No, the full service lifetime for Kepler does not inherently demonstrate poor engineering.
- However, at the base of what you ask is a good question. I do not have detailed knowledge of the design process which was used for Kepler. However, I can make some general comments. A large portion of engineering is making trade-offs based on various requirements. One of the huge limitations in building anything for space is the amount that it weighs. The weight of a satellite determines a large number of aspects of what and how something can be done, how much it costs, what lift capability is required, etc. It can even limit: can this be done at all with current technology? Weight, among many other limitations, usually means that such designs are not made with huge amounts of redundancy – particularly when lives are not at stake – which is not needed to reliably meet the service lifetime criteria which is a basic part of the specifications toward which the engineers are designing. The design of Kepler resulted in it being operational until 4.2 years after being launched. This exceeded the design criteria by 20%. [This percentage may be a bit off. The 3.5 year design lifetime may have been specified as the amount of time on-station, collecting data, not from launch. I would need to double check, but don't have the time at the moment.]
- As to the engineers learning from Hubble: I expect that the engineers involved had access to, and learned from, the problems and failure analyses which were performed on the various issues that have occurred with Hubble.
- For some things, there has come to be an expectation that items designed for space will exceed their designed lifespan. While there are cases like Spirit (rover) and Opportunity (rover) where the designed lifespan has been spectacularly exceeded, it is certainly not always the case. Of course, there are also some times where there are partial, or complete, failures. — Makyen (talk) 03:39, 7 March 2014 (UTC)
- The story I heard is that there are $105 reactions wheels and there are $106 reaction wheels. The lower cost ones are known to be less reliable, but for a mission on a tight budget there may be no choice. This makes perfect sense, but it also seems that if they are known to be unreliable, maybe two spares would have been better than one. But this leads into all sorts of questions about where mass and dollars are best spent, how certain they were that previous reaction wheel failure modes had been addressed, and so on. LouScheffer (talk) 15:18, 7 March 2014 (UTC)