Mayank Chhaya-
A million miles from Earth, NASA’s most expensive $10 billion James Webb telescope, will soon begin looking within barely 100 million years of the universe forming. That would be barely 100 million years after the Big Bang dating back to nearly 14 billion years ago (13.77 billion to be precise).
In a cosmic sense, it would be like watching an egg called the universe cracking in front of our eyes showing us where everything might have come from. Before Webb, the earliest and most distant galaxy that we have detected was by the Hubble telescope within the first 400 million years of the Big Bang.
The James Webb telescope which was launched with textbook precision this morning is now on its way to what NASA calls L2, or the second Lagrange point. “What is special about this orbit is that it lets the telescope stay in line with the Earth as it moves around the Sun. This allows the satellite’s large sunshield to protect the telescope from the light and heat of the Sun and Earth (and Moon),” NASA said.
As of writing this post Webb was reported safe in space, fully powered on, and communicating with ground controllers.
It was oriented correctly with respect to the Sun. “The six reaction wheels of the spacecraft’s attitude control system have been powered on, and they are now responsible for keeping the spacecraft pointing in the right direction – so that its massive sunshield, which is the size of a tennis court and which will deploy over the course of the next week – will be able to keep the telescope protected from solar radiation and heat,” NASA said.
The telescope will take 30 days to reach L2 and some six months later begin its full science work which will involve it looking back billions of years over hundreds of thousands of trillions of miles. Looking back would mean capturing data from the oldest and most distant galaxy as close to the Big Bang as we can get in order to understand our origin. Webb is the most ambitious venture in so much as it seeks to look back nearly 14 billion years to unravel some of the mysteries of our origin.
“Webb will directly observe a part of space and time never seen before. Webb will gaze into the epoch when the very first stars and galaxies formed, over 13.5 billion years ago. Ultraviolet and visible light emitted by the very first luminous objects has been stretched or “redshifted” by the universe’s continual expansion and arrives today as infrared light. Webb is designed to “see” this infrared light with unprecedented resolution and sensitivity,” NASA explains in its backgrounder.
The telescope has many other tasks including studying exoplanets, meaning planets in other solar systems. “Webb will also observe exoplanets located in their stars’ habitable zones, the regions where a planet could harbor liquid water on its surface, and can determine if and where signatures of habitability may be present,” NASA says.
In terms of our immediate interstellar neighborhood, what might be most fascinating and relatable is that Alpha Centauri, a star that is just 4.5 light years away from Earth, which means light takes those many years to cover a distance over 26 trillion miles. That is unfathomably far but on the cosmic scale it is our immediate neighbor. Webb is expected to study whether Alpha Centauri has exoplanets—unlikely—and if it does, what kind.
However, the most interesting target for Webb from our immediate perspective will be the Trappist-1 system, some 40 light years away and known to be home to seven planets. It is a red dwarf star where three out of the seven orbiting planets are Earth-size, rocky and within the habitable zone where water can exist.
TRAPPIST-1, a system of seven Earth-size planets orbiting an ultra-cool dwarf star is between 5.4 billion and 9.8 billion years in age, according to NASA. The term “ultra-cool” does not denote its cool dude quotient as we humans understand it but an astronomical term about a star which has an effective temperature of under 2700 K (2,430 C or 4,400 F).
The age of the TRAPPIST-1 as determined by scientists makes it much older than our solar system—at the higher end almost twice as old. We are 4.5 billion years. This is the most intriguing system with exoplanets that NASA has discovered so far. Seven Earth-size planets around a dwarf are seen as fraught with possibilities of life. Adam Burgasser, an astronomer at the University of California, San Diego, and the first author of a paper published in The Astrophysical Journal in August, 2017, was quoted by NASA as saying, “If there is life on these planets, I would speculate that it has to be hardy life, because it has to be able to survive some potentially dire scenarios for billions of years.”
NASA pointed out that it is not clear what the much older age of the TRAPPIST-1 system means in terms of life having developed on any of the seven planets. “It is unclear what this older age means for the planets’ habitability. On the one hand, older stars flare less than younger stars, and Burgasser and (Eric) Mamajek confirmed that TRAPPIST-1 is relatively quiet compared to other ultra-cool dwarf stars. On the other hand, since the planets are so close to the star, they have soaked up billions of years of high-energy radiation, which could have boiled off atmospheres and large amounts of water. In fact, the equivalent of an Earth ocean may have evaporated from each TRAPPIST-1 planet except for the two most distant from the host star: planets g and h. In our own solar system, Mars is an example of a planet that likely had liquid water on its surface in the past, but lost most of its water and atmosphere to the Sun’s high-energy radiation over billions of years,” it said.
It leaves this tantalizing possibility open: “However, old age does not necessarily mean that a planet’s atmosphere has been eroded. Given that the TRAPPIST-1 planets have lower densities than Earth, it is possible that large reservoirs of volatile molecules such as water could produce thick atmospheres that would shield the planetary surfaces from harmful radiation. A thick atmosphere could also help redistribute heat to the dark sides of these tidally locked planets, increasing habitable real estate. But this could also backfire in a “runaway greenhouse” process, in which the atmosphere becomes so thick the planet surface overheats – as on Venus.”
The relative proximity of this extraordinary system to us—40 light-years or 240 trillion miles (400 trillion kilometers) is like your next-door neighbor in cosmological terms. The light and therefore the data it carries that we are capturing now is just 40 years old and hence quite fresh. It left TRAPPIST-1 sometime in 1977 our time.
TRAPPIST-1 has the fortune of having a slow-burning dwarf whose brightness and temperatures can last trillions of years. “Stars much more massive than the Sun consume their fuel quickly, brightening over millions of years and exploding as supernovae,” Mamajek had then said. “But TRAPPIST-1 is like a slow-burning candle that will shine for about 900 times longer than the current age of the universe.”
[Photo courtesy:https://webb.nasa.gov]
