Mars: Nasa’s Perseverance rover’s first 100 days in pictures

Mars landscape acquired by Nasa's Perseverance rover, using its left Mastcam-Z camera, on 27 March 2021

Nasa’s Perseverance rover is celebrating 100 Martian days (sols) since landing on Mars, where it is hunting for signs of past microbial life, and seeking to investigate the planet’s geology and past climate.

Since touching down on 18 February, the robot has captured some amazing images from around its landing site, Jezero Crater, a 49km (30 mile) wide impact depression just north of the Red Planet’s equator.

A small helicopter, Ingenuity, has also returned aerial images, having made history with the first powered, controlled flights on another planet.

Here is a selection of pictures sent back from the mission so far.

Self portrait of Nasa’s Perseverance Mars rover with the Ingenuity helicopter, on 6 April 2021
image captionOn 6 April, Perseverance used the Watson (Wide Angle Topographic Sensor for Operations and eNgineering) camera to take this selfie next to the Ingenuity helicopter. This photo is made up of 62 individual images which were stitched together once they were sent back to Earth.
Nasa's Ingenuity helicopter can be seen with all four of its legs deployed below the Perseverance rover, on 30 March 2021
image captionDays earlier, Ingenuity had been deployed from underneath the rover.
Nasa’s Ingenuity Mars helicopter is seen here in a close-up taken by Mastcam-Z, on 5 April 2021
image captionThe 1.8kg (4lb) helicopter is regarded as a technology demonstration for the potential of aerial mobility in the thin Martian atmosphere.
Nasa's Ingenuity Mars helicopter on its first flight, on 19 April 2021
image captionOn 19 April, Ingenuity made history with the first powered, controlled flight on another planet. The chopper, which is visible near the centre of this image, rose to about 3m (10ft) above ground and hovered for several seconds, before touching back down.
An aerial image captured by Nasa's Ingenuity Mars helicopter during its second successful flight test on 22 April 2021
image captionIngenuity captured its first colour aerial image while on its second flight. The drone hovered about 5m (16ft) above the ground, tilted and moved laterally 2m (6ft), before returning to the spot it took off from. Perseverance’s tracks and Ingenuity’s shadow are visible on the Martian surface below.
Rover viewed on Mars
image captionIngenuity photographed Perseverance while on its third flight. At the time, the mini-helicopter was about 85m (278ft) from the rover and flying laterally at an altitude of 5m (16ft). One of Ingenuity’s feet is also visible at the edge of the image, just below the rover.
Nasa’s Ingenuity Mars helicopter airborne on its fifth flight, on 7 May 2021
image captionOn 7 May, Ingenuity reached a height of 10m (33ft), before flying 129m (423ft) to a new landing spot.
An image of part of the rover and its tracks on the ground, taken during Perseverance's first drive on 4 March 2021
image captionTwo months earlier, Perseverance went for its first drive since it landed in Jezero Crater. The one-tonne rover is carrying an advanced payload of instruments to gather information about Mars’ geology, atmosphere and environmental conditions.
A rock photographed by Nasa's Mars Perseverance rover's right Mastcam-Z camera, on 28 March 2021
image captionPerseverance is equipped with a laser that is designed to help it collect data on the planet’s geology. While investigating this 15cm (6in) rock, the instrument left the faint row of dots that is visible near its centre.
Rocks photographed by Nasa's Mars Perseverance rover's right Mastcam-Z camera, on 13 May 2021
image captionThe rover is also equipped with a variety of different cameras. This image was taken by the “right eye” of Perseverance’s Mastcam-Z, one of a pair of cameras that provide a stereo view similar to what human eyes would see.
Mars landscape photographed by Nasa's Perseverance rover's left Mastcam-Z camera, on 22 March 2021
image captionThis image was taken with the left Mastcam-Z camera and was selected by public vote to be featured as “Image of the Week” for Week 6 of the rover’s mission.
Santa Cruz hill photographed by Nasa’s Perseverance Mars rover's Mastcam-Z imager, on 29 April 2021
image captionThis image shows Santa Cruz, a hill about 1.5 miles (2.5km) away from the rover. The entire scene is inside Mars’ Jezero Crater; the crater’s rim can be seen on the horizon line beyond the hill.

The Perseverance rover has initial funding to operate for one Mars year, roughly two Earth years.


Tom Cruise: Filming in space and four of his other memorable stunts

Tom Cruise is hoping to blast into the Hollywood record books by shooting the first action movie in space.

Nasa is working with Cruise to film aboard the International Space Station.

There are no details of the film, but Deadline – which first reported the story – said it would not be a new instalment of Mission: Impossible.

The report also said Cruise, 57, is also working with Elon Musk’s SpaceX, which will transport two US astronauts to the ISS for Nasa later this month.

Nasa administrator Jim Bridenstine wrote on Twitter: “Nasa is excited to work with Tom Cruise on a film aboard the Space Station!”

Musk replied to say the project “should be a lot of fun!”

Cruise played an astronaut in 2013 film Oblivion, when he safeguarded Earth’s natural resources from alien invaders.

He also narrated the 2002 Imax documentary Space Station 3D. It’s not known when the star will blast off to the ISS for real.

Risky business: 4 daredevil stunts from Cruise’s career

By Ian Youngs, entertainment reporter

As well as being one of Hollywood’s most popular action heroes, Cruise is known as a daredevil who does many of his own stunts.

In an interview about his new Top Gun sequel, co-star Miles Teller says: “I think when Tom hears that something’s impossible or can’t be done, that’s when he gets to work.”

That sounds not unlike his Mission: Impossible character Ethan Hunt, who has been seen in many of the most daring scenes.

1. Leaping off a roof (and breaking an ankle)

In 2017, he broke his ankle while jumping from one rooftop to another (attached to a cable) for Mission: Impossible – Fallout.

Despite instantly knowing he was injured, he carried on by hauling himself onto the roof and running off.

“I knew it was broken,” he later told The Graham Norton Show. “I just said, ‘Ugh,’ and I ran past the camera. We got the shot, it’s in the movie.”

His co-star Simon Pegg joked: “Everyone said, when you got up and ran out of shot, ‘Oh, that’s so him. To complete the shot with your foot hanging off – that’s so him.'”

2. Climbing a skyscraper

In 2011’s Mission: Impossible – Ghost Protocol, Hunt is seen scaling the Burj Khalifa in Dubai – the world’s tallest building – from the outside.

Although Cruise trained for four months and was wearing a harness – which was edited out – he said he struggled with crosswinds as he tried to swing in through a window.

“It took a while to work out how not to come slamming into the building head first,” he said.

3. Hanging off a plane during take-off

In Mission: Impossible – Rogue Nation, Cruise hangs from the side of a plane by his fingertips as it takes off. It was really him, and it was a real plane.

He performed the stunt four times over two days, again wearing a harness, but the crew had to scour the runway for the tiniest items that could have been thrown up and hit him.

“While we are going down the runway, we’re worried about bird strikes, any kind of particle that the propellers could pick up, any kind of stone,” Cruise told USA Today.

“I remember I got hit by a stone that was so tiny, you cannot believe. I thought it broke my rib. Lucky it went to my vest and not my hands or my face, it would have penetrated and gone right through.”

4. Falling off a cliff

One of his other famous stunts appears in the opening scene of Mission: Impossible 2, where Hunt climbs – and then almost falls off – a vertigo-inducing cliff, apparently with no ropes.

Cucumber-cool Cruise was actually attached to a thin safety wire, which was later erased – but that did little to calm director John Woo’s nerves.

“I was really mad that he wanted to do it, but I tried to stop him and I couldn’t,” he told Entertainment Weekly. “I was so scared I was sweating. I couldn’t even watch the monitor when we shot it.”


China rocket debris ‘disintegrates over Indian Ocean’ – Chinese media

The rocket was launched to carry a Chinese space station section into orbit

Debris from a Chinese rocket that had been hurtling back towards Earth has disintegrated over the Indian Ocean, China says.

The bulk of the rocket was destroyed during the re-entry, but parts landed at a location 72.47° East and 2.65° North, Chinese state-run media reported.

The point lies west of the Maldives.

US and European tracking sites had been monitoring the uncontrolled fall of the Long March-5b vehicle.

Chinese state media said parts of the rocket re-entered the atmosphere at 10:24 Beijing time (02:24 GMT) on Sunday.

US Space Command said in a statement that it could “confirm the Chinese Long March-5b re-entered over the Arabian Peninsula”. It was “unknown if the debris impacted land or water,” the agency said.

Ahead of the rocket’s re-entry there were fears that debris could come down in an inhabited area. US Defence Secretary Lloyd Austin said China had been negligent in letting the rocket fall out of orbit.

However, space experts had predicted that the chances of anyone actually being hit by a piece of space junk were very small, not least because so much of the Earth’s surface is covered by ocean, and huge land areas are uninhabited.

The main segment from the Long March-5b vehicle was used to launch the first module of China’s new space station last month.

At 18 tonnes it is one of the largest items in decades to have an undirected dive into the atmosphere.

The US said last week it was watching the path of the object – but had no plans to shoot it down.

Various space debris modelling experts had pointed to late Saturday or early Sunday (GMT) as the likely moment of re-entry.

The experts predicted that most of the vehicle would burn up during its final plunge through the atmosphere, although there was always the possibility that metals with high melting points, and other resistant materials, could survive to the Earth’s surface.

When a similar core stage returned to Earth a year ago, piping assumed to be from the rocket was identified on the ground in Ivory Coast, Africa.

China has bridled at the suggestion that it has been negligent in allowing the uncontrolled return of so large an object.

Commentary in the country’s media had described Western reports about the potential hazards involved as “hype” and predicted the debris would fall somewhere in international waters.

Very rare space pic

The moon passed between Nasa’s Deep Space Climate Observatory and the Earth allowing this rare pic

Deep Space Climate Observatory (DSCOVR; formerly known as Triana, unofficially known as GoreSat is a National Oceanic and Atmospheric Administration (NOAA) space weather, space climate, and Earth observation satellite. It was launched by SpaceX on a Falcon 9 v1.1 launch vehicle on 11 February 2015, from Cape Canaveral. This is NOAA’s first operational deep space satellite and became its primary system of warning Earth in the event of solar magnetic storms.

On 6 July 2015, DSCOVR returned its first publicly released view of the entire sunlit side of Earth from 1,475,207 km (916,651 mi) away, taken by the EPIC instrument. The moon is roughly 250,000 miles from earth. EPIC provides a daily series of Earth images, enabling the first-time study of daily variations over the entire globe. The images, available 12 to 36 hours after they are made, have been posted to a dedicated web page since September 2015.

The Moon transiting Earth, 16 July 2015. The far side of the Moon faces the camera.

World’s Most Powerful Rocket Passes Test

The core stage of NASA’s Space Launch System (SLS) rocket fired all four of its RS-25 engines for a little more than eight minutes—about the same duration needed to launch the Artemis I mission to the Moon. The successful hot fire tested the engines’ ability to direct thrust as well as handle throttling up to 109% power. Two massive propellant tanks that hold more than 733,000 gallons of liquid hydrogen and liquid oxygen fed the burning engines at the bottom of the stage. According to Stennis Center Director Richard Gilbrech, “This final test in the Green Run series represents a major milestone for this nation’s return to the Moon and eventual mission to Mars.”

Space Hotel Aims to Open in 2027

A proverbial interstellar construction company has announced plans to build a lavish space hotel and they hope to welcome their first guests to the fantastic facility in just six years. During a recent online event, the Orbital Assembly Corporation (OAC) reportedly provided a glimpse of what their ‘Voyager Station’ will look like once it has been completed and shared details as to how they intend to pull off such an audacious project. Designed to accommodate approximately 400 people spread out throughout 24 “habitation modules,” the ring-shaped space station will measure around 650 feet in diameter and reside in low Earth orbit, where it will rotate in a manner that will generate gravity similar to that found on the moon.

Much like luxurious cruise ships here on Earth, the hotel will be equipped with a vast array of amenities including all manner of restaurants and recreational activities, specifically a bevy of attractions designed to take advantage of the facility’s out-of-this-world setting. In addition to space tourists, the company hopes to sell spots on the station to various governments and any other large organizations that may wish to study or make use of its unique artificial gravity. OAC says that they hope to begin construction on the space hotel sometime around 2025, when a specially designed craft known as the Structure Truss Assembly Robot will be dispatched into space and begin building the framework of the facility.

Assuming that there are no complications in the complex construction process, which may border on wishful thinking at this stage of the station’s development, they anticipate spending two years completing the project and ultimately opening for business in 2027. With that in mind, those hoping to visit the space hotel sometime in the future will likely want to start saving now as the estimated cost for just a three-and-a-half-day visit is a whopping $5 million. Alas, with that kind of price tag, most of us will likely be stuck in the unenviable position of looking at someone’s else vacation pictures from the historic station rather than experience it for ourselves.

SpaceX: Starship lands safely… then explodes

Elon Musk’s SpaceX has successfully landed one of its Starship prototypes at the end of a high-altitude test flight.

It is the first time the space exploration company has pulled this off, after the ship’s predecessors crashed into the ground.

But that wasn’t the end of the story. A fire then developed around SN10’s base and eight minutes later it exploded on the landing pad in Boca Chica, Texas.

First ‘space helicopter’ set to take to Martian skies

NBC News

When NASA’s Perseverance rover touches down next week, it will carry one of the strangest devices ever seen on Mars — a drone destined to make the first controlled flights on an extraterrestrial planet.

Dubbed “Ingenuity,” the drone weighs just 4 pounds, and it will stay stored beneath the rover’s belly while Perseverance runs through its initial surface checks and experiments.

But about the middle of April, the rover will scout out a flat area without large rocks to deploy the drone, and soon after that Perseverance will release Ingenuity to make the first flights on Mars.

“It’s pretty unique in that it’s a helicopter that can fly around,” said Tim Canham, the operations lead for the Ingenuity project at NASA’s Jet Propulsion Laboratory in California.

“There was a balloon mission on Venus years ago, so we can’t claim to be the first aircraft,” he said, referring to the two Soviet Vega space probes that deployed balloons attached to scientific instruments in the clouds on Venus in 1985. “But we can claim we’re the first powered aircraft outside Earth.”

Canham will coordinate the five test flights scheduled for the Ingenuity drone over 30 days, with each at least three days apart.

“The first flight will be very basic – it will just go straight up, hover and go straight down,” he said. “After that, we’ll do a couple of flights where we go horizontally, to test how it works.”

The car-size Perseverance rover has seven complex scientific instruments, so it can take panoramic video, monitor the weather, perform ultraviolet and X-ray spectroscopy on anything it finds, and look for signs of ancient microbial life.

But, Ingenuity will carry out no science on its test flights. It will only take photographs of the Martian terrain with its two cameras, one facing forward and one down.

Instead, the Ingenuity project is designed to show drones can be an important addition to the ongoing explorations of distant planets, Canham said.

“Our job is really to prove that the aerodynamics, as we’ve tested them here, work also on Mars,” he said.

Mars is a hard place to fly, which is why Ingenuity weighs so little and needs two counter-rotating 4-foot-long helicopter rotors to stay aloft.

Perseverance, nicknamed Percy, is a car-sized Mars rover designed to explore the Jezero crater on Mars as part of NASA’s Mars 2020 mission. It was manufactured by the Jet Propulsion Laboratory and was launched on 30 July 2020, at 7:50 a.m. EDT (11:50 UTC), and is scheduled to land on Mars on 18 February 2021, 3 p.m EST/8 p.m UTC.

Perseverance carries seven scientific instruments to study the Martian surface at Jezero crater. It carries several cameras and two microphones.

Technical details
Length 2 m (6 ft 7 in)
Diameter 2.7 m (8 ft 10 in)
Height 2.2 m (7 ft 3 in)
Launch mass 1,025 kg (2,260 lb)
Power 110 W (0.15 hp)

Photos of Earth from the ISS

The Cupola is an ESA-built observatory module of the International Space Station (ISS). Its seven windows are used to conduct experiments, dockings and observations of Earth. It was launched aboard Space Shuttle mission STS-130 on 8 February 2010 and attached to the Tranquility (Node 3) module. With the Cupola attached, ISS assembly reached 85 percent completion. The Cupola’s 80 cm (31 in) window is the largest ever used in space.

space photographer

Stunning views from the Cupola

space florida

South Florida

space ghana

Storms over Ghana, Africa

space great lakes

Great Lakes

space horn of africa

Horn of Africa

space ne coast brazil

Northeast coast of Brazil

space new york and south

New York City looking south

space southwest libya

Southwest Libya

space tibet


space tokyo


spave mt vesuvius

Mt. Vesuvius, Italy

Historical space photos

space moon

Earth from the Moon during an Apollo mission

space shuttle1

Space Shuttle blasting off into the clouds

Breaking through the clouds

space shuttle

World’s Largest Telescopes


This list of the largest optical reflecting telescopes with objective diameters of 3.0 metres (120 in) or greater is sorted by aperture, which is one limit on the light-gathering power and resolution of a reflecting telescope’s optical assembly.


The Gran Telescopio Canarias (GranTeCan or GTC), also known as the Great Canary Telescope is a 10.4 m (410 in) reflecting telescope located at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain.

Construction of the telescope, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level, took seven years and cost €130 million (£112 million). Its installation had been hampered by weather conditions and the logistical difficulties of transporting equipment to such a remote location. First light was achieved in 2007 and scientific observations began in 2009.

The GTC Project is a partnership formed by several institutions from Spain and Mexico, the University of Florida, the Universidad Nacional Autónoma de México and the Instituto de Astrofísica de Canarias (IAC). Planning for the construction of the telescope, which started in 1987, involved more than 1,000 people from 100 companies.

As of 2015, it is the world’s largest single-aperture optical telescope. The distribution of the availability of time to use the telescope meets its financial structure: 90% Spain, 5% Mexico and 5% the University of Florida.




The W. M. Keck Observatory is a two-telescope astronomical observatory at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes feature 10 m (33 ft) primary mirrors, currently among the largest astronomical telescopes in use. The combination of an excellent site, large optics and innovative instruments has created the two most scientifically productive telescopes on Earth.





The Southern African Large Telescope (SALT) is a 10-metre class optical telescope designed mainly for spectroscopy. It consists of 91 hexagonal mirror segments each with a 1 metre inscribed diameter, resulting in a total hexagonal mirror of 11.1 m by 9.8 m. It is located close to the town of Sutherland in the semi-desert region of the Karoo, South Africa. It is a facility of the South African Astronomical Observatory, the national optical observatory of South Africa.





The Hobby–Eberly Telescope (HET) is a 9.2-meter (30-foot) aperture telescope located at the McDonald Observatory in Texas. It is one of the largest optical telescopes in the world and combines a number of features that differentiate it from most telescope designs, resulting in greatly lowered construction costs. For instance, the primary mirror is constructed from 91 hexagonal segments, which is less expensive than manufacturing a single large primary. Furthermore, the telescope’s main mirror is fixed at a 55° angle and can rotate around its base. A target is tracked by moving the instruments at the focus of the telescope; this provides access to about 70–81% of the sky at its location and allows a single target to be tracked for up to two hours.

The Hobby–Eberly Telescope is operated by The University of Texas McDonald Observatory for a consortium of institutions which includes The University of Texas at Austin, Pennsylvania State University, Stanford University, Ludwig Maximilians University of Munich, and Georg August University of Gottingen.





The Large Binocular Telescope (LBT) is an optical telescope for astronomy located on Mount Graham (10,700-foot (3,300 m) in the Pinaleno Mountains of southeastern Arizona, and is a part of the Mount Graham International Observatory. The LBT is currently one of the world’s most advanced optical telescopes; using two 8.4 m (27 ft) wide mirrors, with a 14.4 m center-center separation, it has the same light gathering ability as an 11.8 m (39 ft) wide single circular telescope and detail of a 22.8 m (75 ft) wide one. Either of its mirrors would be the second-largest optical telescope in continental North America, behind the Hobby–Eberly Telescope in West Texas; as of summer 2014, it would still be the largest monolithic, or non-segmented mirror, in an optical telescope. Optical performance of the telescope is excellent, and Strehl ratios of 60–90% in the infrared H band and 95% in the infrared M band have been achieved by the LBT.

The LBT was originally named the “Columbus Project”. It is a joint project of these members: the Italian astronomical community represented by the Istituto Nazionale di Astrofisica, the University of Arizona; University of Minnesota, University of Notre Dame, University of Virginia, the LBT Beteiligungsgesellschaft in Germany (Max Planck Institute for Astronomy in Heidelberg, Landessternwarte in Heidelberg, Leibniz Institute for Astrophysics Potsdam (AIP), Max Planck Institute for Extraterrestrial Physics in Munich and Max Planck Institute for Radio Astronomy in Bonn); The Ohio State University; Research Corporation in Tucson.





Subaru Telescope is the 8.2 metre flagship telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the world from its commission until 2005.

In 1984, the University of Tokyo formed an engineering working group to study the concept of a 7.5-metre telescope. In 1985, the astronomy committee of Japan’s science council gave top priority to the development of a “Japan National Large Telescope” (JNLT), and in 1986, the University of Tokyo signed an agreement with the University of Hawaii to build the telescope in Hawaii. In 1988, the National Astronomical Observatory of Japan was formed through a reorganization of the University’s Tokyo Astronomical Observatory, to oversee the JNLT and other large national astronomy projects.





The Very Large Telescope (VLT) is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2 m across, which are generally used separately but can be used together to achieve very high angular resolution. The four separate optical telescopes are known as AntuKueyenMelipal and Yepun, which are all words for astronomical objects in the Mapuche language. The telescopes form an array which is complemented by four movable Auxiliary Telescopes (ATs) of 1.8 m aperture.

The VLT operates at visible and infrared wavelengths. Each individual telescope can detect objects roughly four billion times fainter than can be detected with the naked eye, and when all the telescopes are combined, the facility can achieve an angular resolution of about 0.001 arc-second (This is equivalent to roughly 2 meters resolution at the distance of the Moon). In single telescope mode of operation angular resolution is about 0.05 arc-second.

The VLT is the most productive ground-based facility for astronomy, with only the Hubble Space Telescope generating more scientific papers among facilities operating at visible wavelengths. Among the pioneering observations carried out using the VLT are the first direct image of an exoplanet, the tracking of individual stars moving around the supermassive black hole at the centre of the Milky Way, and observations of the afterglow of the furthest known gamma-ray burst.





The Gemini Observatory is an astronomical observatory consisting of two 8.19-metre (26.9 ft) telescopes, the Gemini North and Gemini South at different sites in Hawaii and Chile, respectively. Together, the twin Gemini telescopes provide almost complete coverage of both the northern and southern skies. They are currently among the largest and most advanced optical/infrared telescopes available to astronomers.

The Gemini telescopes were built and are operated by a consortium consisting of the United States, Canada, Chile, Brazil, Argentina, and Australia. This partnership is managed by the Association of Universities for Research in Astronomy (AURA). The United Kingdom dropped out of the partnership at the end of 2012 and the Gemini Observatory has responded to this by significantly reducing its operating costs, so that no new partners are required beginning in 2013.





The Magellan Telescopes are a pair of 6.5 m (21.3 ft) diameter optical telescopes located at Las Campanas Observatory in Chile. The two telescopes are named after the astronomer Walter Baade and the philanthropist Landon T. Clay.

First light for the telescopes was on September 15, 2000 for the Baade, and September 7, 2002 for the Clay.

A collaboration between Carnegie Institution for Science, University of Arizona, Harvard University, The University of Michigan and the Massachusetts Institute of Technology built and operate the twin telescopes.

It was named after the sixteenth-century Portuguese explorer Ferdinand Magellan.





The BTA-6 is a 6-metre (20 ft) aperture optical telescope at the Special Astrophysical Observatory located in the Zelenchuksky District on the north side of the Caucasus Mountains in southern Russia.

The BTA-6 achieved first light in late 1975, making it the largest telescope in the world until 1990, when it was surpassed by the partially constructed Keck 1. It pioneered the technique, now standard in large astronomical telescopes, of using an altazimuth mount with a computer-controlled derotator.

For a variety of reasons, BTA-6 was never able to operate near its theoretical limits. Early problems with poorly fabricated mirror glass were addressed in 1978, fixing the most serious issue. But due to its location down-wind of numerous large mountain peaks, astronomical seeing is rarely good. The telescope also suffers from serious thermal expansion problems due to the large thermal mass of the mirror, and the dome as a whole which is much larger than necessary. Upgrades have taken place throughout the system’s history and are ongoing to this day.