65 years

[Alastair Rae]

Prompted by the news report Should NASA Ditch Manned Missions to Mars?, I was reminded of the xkcd graph, 65 years with its mouse-over quote:

The universe is probably littered with the one-planet graves of cultures which made the sensible economic decision that there's no good reason to go into space--each discovered, studied, and remembered by the ones who made the irrational decision.

[ronin]

Trouble is that it is happening.

After the Mars mission today someone today was asked about a person on Mars their timescale was much more then I expected them to say.

Few weeks ago at talk on producing images from the worlds big scopes the presenter was pushing the advantages of the land based systems. I asked afterwards if he didn't think that withdrawing from space telescopes to ground based ones was not a backwards step. He couldn't see why we would bother with space bourne systems when we could get good images from the ground.

It really seemed to me to be a case of we have put a few up, we can say we have done it now lets withdraw back to the ground.

[Sp@ce_d]

The crunch will come when we realise we don't have the resources left to actually get of the ground... that day may be closer than we think

[JulianO]

Few weeks ago at talk on producing images from the worlds big scopes the presenter was pushing the advantages of the land based systems. I asked afterwards if he didn't think that withdrawing from space telescopes to ground based ones was not a backwards step. He couldn't see why we would bother with space bourne systems when we could get good images from the ground.

It really seemed to me to be a case of we have put a few up, we can say we have done it now lets withdraw back to the ground.

As far as telescopes go, it depends enormously what you want to do. The Hubble has done stunningly well, but ground based optical telescopes are probably getting better than that now with adaptive optics. Ground based optical has huge benefits in many areas. OK we have the pesky atmosphere, but against that there is a lot going for them.

• Easy maintenance - you can at least drive up to them and send some engineers out to them.
  
• Upgrade - You can swap instruments as technology improves.
  
• Building - Try launching a 40m mirror into space - very expensive, very technically difficult - the weight alone may be prohibitive.
  
• Adaptive optics - which can cancel out a lot of the shimmer from the atmosphere.
  
• Bandwidth - you can transmit the data over fibre optics
  

So ground based telescopes for optical may be the way ahead, at least until we get to the moon.

However as I said, in space you're above the atmosphere, and for some bands that is really the only way it can be done. Count the number of gamma or x-ray telescopes there are on the ground! Similarly certain types of IR can only be done practically from space - an increasingly important band when wanting to look at the red shifted early universe.