Hubble has been one of the most valuable scientific projects of recent times, some even say that we have learned more with Hubble than we did with Apollo but like all good things it must come to an end and that end will be coming in the not too distant future.
But Hubble has successor waiting in the wings, the James Webb Space Telescope, this builds upon the success of the Hubble but with 21st century technology and promises even greater discoveries, the only problem is that it’s now 14 years late and about 10 times over budget and still won’t be launched until 2021 , so why can’t we keep Hubble going and why is the JWST so late and so expensive.
Big projects like the James Webb Space Telescope are often beset with delays and problems. The Hubble its self was no stranger to controversy. Designed in the 1970’s, It was due to be launched in 1983 but with technical issues, budget restrictions and the Challenger disaster, it was delayed for 7 years. Only when it was in orbit did they find out that the most perfectly ground mirror in history had been made with a tiny error in its shape, effectively making it sshort-sighted It took a further three years before a fix was created to finally get it working as it should.
The Hubble was designed to be serviced and upgraded in orbit and over the last 25 years ,it has undergone five service missions. This was all done using the Space Shuttle and at the end of each service mission ,the shuttle would move the Hubble to a higher orbit.
This is done because although Hubble is in orbit, the height of this orbit still low enough to be in the very, very thin upper atmosphere and this creates drag which slows it down over time.
This slowing down causes the orbit to decay and become lower still which increases the drag which slows it more and so on and so forth and if nothing is done they will eventually crash back to earth and burn up.
On Oct 5th 2018 Hubble went in to sleep mode when one of it’s gyroscopes failed. These are devices which are used to help guide and keep its orientation in orbit and although it does have six, four have now failed. Three of the six were an older design and that was to be expected but this was one of the three newer design ones. Although it ideally needs three to operate, one for each axis, X,Y and Z new operational techniques mean that it can work with just one. As part of the ongoing servicing of the hubble the newer design gyro’s along with a list of other equipment had been installed on a previous service mission but these are mechanical devices and as such they will wear out eventually.
The problem is, we no longer have the space shuttle to do any further service missions or boost Hubble’s orbit, so even if nothing else goes wrong, Hubble will eventually fall back to earth some where between 2028 and 2040.
This rather vague date is because it’s sun activity which affects the expansion of the Earth’s atmosphere and the ultimately the drag on Hubble and that’s something we can only estimate in the future.
It wasn’t planned to end like this, one of the scenarios was that the Hubble would be brought back to earth by the shuttle and maybe placed in somewhere like the Smithsonian museum.
If there is the political will, Hubble’s life could easily be extended. There has been talk of a commercial mission using a manned version of the Dream Chaser to service Hubble and boost its orbit just in case there are further delays with the James Webb Space Telescope or god forbid that something happens during it’s launch but either way, we now just don’t have a vehicle that could bring it back to Earth safely.
But why is the James Webb taking so long to literally get off the ground. Well ,one of the reasons is where it will take up its final position.
Unlike the Hubble which just 540km miles above the earth, the James Webb will actually orbit the sun 1.5 million km away from earth at the second Lagrange point or L2 where the gravitational effects of the Sun, moon and earth cancel each other out and allow it to be in a stable orbit with regard to all three.
This means that fixing the James Webb unlike the Hubble if something were to go wrong would range from the extremely difficult to nigh on impossible, especially when we don’t have any manned spacecraft capable of travelling that far out.
So everything has to work perfectly, which means testing, testing and more testing and even testing the tests. The memory of the Hubble fiasco which was basically down to a failure of testing looms large in the minds of Northrop Grumman the primary contractor and the others involved.
The other issue is that no one has built anything quite like the James Webb before. At the time of its conception at least 10 of the technologies required had yet to be invented. Things like the giant 5 layer sunshield, the size of a tennis court and that will take 2 weeks to deploy from its folded up form. And its not only the detectors, sunshield and control systems which will have to work just a few degrees above absolute zero.
Everything on the detection side of the telescope must be a cold as possible so as not to interfere with the tiny amounts infra-red light that the James Webb is looking for from the farthest reaches of the universe from the first galaxies that formed after the big bang.
This includes the mirror which at 6.5 meters across has 6.25 times the light collecting area of the Hubble which has a 2.4 meter mirror.
A single mirror this large wouldn’t fit in any spacecraft, so it’s made up of 18 hexagonal sections which are individually controlled to focus the light on to the sensors.
Inventing the technologies, ironing out the bugs and the exhaustive testing of these brand new ideas takes a lot of time and a lot of money and this is the other main reason for why its taking so long to get the James Webb ready.
Back in 1996 when the JWST was conceived, the original price was $1bn and it was expected to be launched around 2007 but equally no one at the time actually knew how to build it and this was very much a best guess estimate.
Its been said since that NASA projects like this are wildly optimistic and are pitched low so as not to scare of potential funding, knowing that they can always go back and ask for more but as time went by the difficulties began to mount up and so did the costs.
This meant NASA had to keep going back to congress for more funding, which took more time and delayed the whole project. This repeating process has gone on and on until now when its total is expected to be just short of $10bn.
The problem for the government is that if it pulls the plug then not only will science be losing a highly anticipated tool but then they have spent billions with nothing to show for it which would in some ways be worse and making it almost too big to fail from a fiscal point of view.
Some have said that it was all done backwards and that we should have built it with existing technologies that have a known price tag. The problem with this argument is that it would never have been built because we didn’t have the technology to do so and waiting for someone to invent it without an end goal just won’t happen. If this methodology had been applied to Apollo we would never have gotten to the moon.
So we may well be stuck with the price but the least NASA can now do is try and eliminate as many of the possible points of failure as they can. This is likely to become the most highly scrutinised project in space history so far but they can console themselves that it looks an absolute bargain compared the $400bn for the development of just one plane, the F-35.
So what do you think we should do with Hubble, fix it or leave it to a controlled re-entry burn up and what’s your thoughts on the JWST, let me know in the comments and don’t forget to check out some of our other videos and it just remains for me to say thanks for watching and please subscribe, thumbs up and share.
