Not long now and the most powerful space telescope ever will be ready to go to work!

A milestone; NASA and ESA say the alignment of the James Webb telescope launched in December is complete. It means that the telescope’s mirrors now reflect focused light from space into each instrument, and each instrument manages to use that light to form a super-sharp image of a portion of that space.

Mosaic

To illustrate that, ESA and NASA have released a mosaic (you can see it below). Each image on this proves that the instruments are fully aligned with the telescope and thus see space clearly. The images also show part of the Large Magellanic Cloud; a small satellite galaxy of the Milky Way.

The mosaic is in red colors. The color scheme was deliberately chosen to emphasize the contrast. So we don’t see this part of the space as we would see it with our own eyes. Image: NASA/STScI.

The instruments

The size and position of the images reflect the size and position of the fields of view of the different instruments. On the far left you first see an image of NIRSpec. This is a spectrometer; an instrument that can split light into different colors and based on this, for example, can tell more about the properties – such as temperature, mass and chemical composition – of the object that emits or reflects this light. The instrument is therefore not designed to visualize the universe optically, but it can make images for calibration purposes and the selection of suitable research objects.

Directly next to it we see NIRCAM, this near infrared camera is especially suitable for detecting light from young stars and galaxies in the making. An image of MIRI can be seen next to NIRCAM: this instrument focuses on radiation in the mid-infrared. Below we see the Fine Guidance Sensor† This is not really a scientific tool; the Fine Guidance Sensor By establishing and maintaining James Webb’s position relative to specific stars in James Webb’s field of view, it allows it to remain focused on objects to be studied for extended periods of time. And finally there is NIRISS, which stands for Near Infrared Imager & Slitless Spectrograph† It is a combination of a near infrared camera and a spectrometer and is used, for example, to detect exoplanets.

Not done yet

An important hurdle has been cleared with the alignment of the telescope. But the telescope is not quite ready for the first real observations yet. For example, the scientific instruments must first be adjusted properly. Those instruments contain many components – lenses, masks, filters, etc. – that still need to be configured. In addition, the telescope will be ordered in the coming period to focus on different parts of the universe, whereby the amount of solar radiation that falls on James Webb varies widely. The aim is to confirm that the temperature of the observatory – for optimal results, the mirrors and instruments must have a temperature of -223 degrees Celsius – remains stable under those conditions.

James Webb is still expected to be fully operational sometime this summer. And that’s something to look forward to; NASA and ESA also report at this stage that the telescope’s optical performance is still better than expected.