The Largest Telescope In Space To See Life For Fraction Of JWST Cost
I was at the NASA Visitors Space Center in Florida recently. There are many interesting assets to experience. I was impressed by the size of the Space shuttle. It was much larger than it seems to be on the images. We could see the model of Hubble Space telescope.
As part of the exhibition, we watched a movie about the creation and launch of the James Webb Space Telescope — the marvel of science and technology. Its journey started many years ago and despite the cost of 10 billion dollars, it is worth every penny. It allows the scientists to explore the secrets of the cosmos for all of us bringing stunning revelation about the Universe we are living in. I can’t wait to see what the next telescope will tell us. For example, the Habitable Exoplanet Observatory (HabEx), is a concept for a telescope to directly image planetary systems around Sun-like stars. We could detect potential signs of life on exoplanets.
The current generation of telescopes was designed to fit into the fairings of the largest rocket launchers in operation. That is the reason, why JWST was unfolding. The process was nerve-bracking with more than 400 single points of failure without any recovery option. The whole engineering, testing, and retesting process took more than 10 years and increased the budget multiple times. Even the concept design of the HabEx telescope was created in 2019 about 1 year after the Space X Falcon Heavy's first launch. Perhaps we could reinvent the concept using the latest progress in rocket technology and other NASA plans in progress.
However, I think it is time to redesign the concept. We can build a much larger telescope for a fraction cost of JWST while leveraging the NASA Gateway program. Let me tell you how.
Firstly, we should acknowledge that SpaceX Starship is likely going to work. The second launch was not a full success, but the first stage delivered the lifting performance and the second stage damaged itself while dumbing additional fuel in deep space. As the third launch is imminent, I would assume that we will have a reliable and efficient booster to lift much larger telescopes. Even Elon Musk mentioned that Starship could be converted into one big telescope. But that is not the only change.
The second important input is that we should have people around the Moon orbit in few years. There might not be the moonbase yet, but the HALO central module of the Gateway space station orbiting Moon is being worked on. Other modules are also under development. So there is a high chance that it will allow to host astronauts for weeks or even months soon. And we could put them to work.
A spacewalk is when an astronaut is out in space just in his/her space suit. Do you know that more than 150 spacewalks were executed to assemble the International Space Station? I think that we can use the highly skilled and trained astronauts to assemble the larger telescope while being in Moon orbit. There is also a precedent, The Hubble telescope was repaired and serviced many times thanks to the Earth's proximity.
So how big telescope we could build? JWST consists of 18 hexagonal mirror segments. It is 6.5 meters across in total. The cargo bay of the Starship should be 8 meters in diameter. Each segment will be larger than JWST. The cargo shall also be about 18 meters in length, so we should fit in 18 hexagons. That will create a mirror 40 meters in diameter, which is slightly larger than an Extremely Large Telescope. That aperture will be able to collect 30x more light than JWST while having a much better angular resolution.
What about the weight? Will Starship handle it? Well, each JWST mirror piece, is made from durable and lightweight beryllium. It weighs only about 20 kilograms (46 pounds), so 18 segments are 360 kg. So we should count 500–1000 kg for each segment of the 8-meter mirror. However, mirrors are only a small part of the overall observatory. The total weight of the JWST observatory is 6,500 kg (14,300 lbs) including actuators, fuel for maneuvers, thrusters, communication, etc. Hence even with the larger reaction wheels and fuel reserves, we should be comfortable within the cargo capacity of a single Starship delivery to Moon orbit (about 100.000 kg). The Starship will be parked close to the Gateway station hosting 4 astronauts. So we could easily dedicate 2 of them for the assembly.
The simplest seems to open the cargo bay from the top of the rocket and then push out segment by segment. The space probe will be mounted on the central mirror segment. For simplicity, the main module could be fixed and held in position by the Starship. So there is no risk of some collision.
The astronauts will need to release from the cargo the remaining 18 segments and mount them at the right places. They will also need to install the guides, shades, etc. However, it should be much simpler work than complete ISS. I would assume that it could be done in a couple of weeks. When the system is completed, the operation team on Earth could run all the tests, and probe that everything is working properly.
Once all this is accomplished, we could dispatch the observatory to deep space. As Gateway will be parked at a specific near-rectilinear halo orbit (NRHO) around the Moon, it is very close to the Moon Transfer orbit. So just a small nudge of about 100 m/s velocity difference is required to get to L2 Lagrange point, where the observatory should be parked. That could be achieved very gently. We could fire the thrusters and return the Observatory to the Gateway for an inspection. The second component, the star shade, could be launched directly to L2.
We will have Starship operation and astronauts traveling around the Moon in few years. So we can build even larger than Extremely Large telescope for a fraction of the JSWT cost. Not only we will have a more than decent successor of the Hubble, but we will be able to see directly hundreds of exoplanets, tens of potentially habitable worlds, or even habitable exomoons. Can anybody ask NASA to start planning it? I would love to know if there is a life elsewhere.
