Category Science

What is the Demo 2 mission?

NASA, the U.S. space agency, partnered with SpaceX, a private space company, to send astronauts to the International Space Station (ISS) in a commercially built and operated spacecraft. As part of this partnership, the first crewed test flight, Demo-2, was launched successfully on May 30, 2020, from NASA’s Kennedy Space Center in Florida. The SpaceX’s Crew Dragon spacecraft carried NASA astronauts Robert Behnken and Douglas Hurley on the company’s Falcon 9 rocket.

The Demo-2 mission has many firsts to its credit. SpaceX’s Crew Dragon, responsible for mission, is the first privately designed and built spacecraft to carry astronauts to space. The company has hitherto been delivering only cargo to the space station. The launch also marked the first time since the final flight space shuttle Atlantis in 2011 that NASA had sent from the U.S. soil. Ever since the retirement of Atlantis, human spaceflights to and from the ISS have been carried out using Russia’s Soyuz rocket.

With the success of Demo-2 NASA and SpaceX plant to launch the company’s first full mission with astronauts in October. Known as Crew-1, the mission will see three U.S. astronauts and one Japanese astronaut launch in a SpceX Crew Dragon capsule to the ISS.

 

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Where do old satellites go?

We’ve been satellites to space for a long time. Each satellite serves a different purpose. While some help us predict the weather, some let us watch television, and some help us find our way to different places. However, like all machines, satellites have an expiry date. They can’t go on forever. So what happens to these satellites when they are close to their end?

A cemetery on Earth

When a trusty satellite’s time has come, scientists have two choices depending on how high the satellite is. If it is closer to Earth, engineers will use the last bit of fuel remaining in the satellite to slow it down. This way, it will fall out of space. Towards Earth’s orbit and burn up in the atmosphere. This can be done for bigger satellites, spacecrafts and space stations in low orbit, the solution is for operators to plan for the final destination on Earth to make sure any debris that remains falls in a remote area.

Most likely, this remote area is a place in the Pacific Ocean farthest away from human civilization. It also has a nickname – the Spacecraft Cemetery.

A graveyard in space

The second option that scientists and engineers have is to send satellites in higher orbits even farther away from Earth. This is because it takes a lot of fuel to slow down a satellite enough to fall back into the atmosphere, fuel that these satellites do not have. Hence, with whatever little fuel remains, the satellite is blasted farther into space, never making its way back to Earth.

These satellites are sent into an orbit almost 300km away from the farthest active satellites in space. This place is called the ‘Graveyard orbit’ and is located about 36,000km above Earth.

Some of these satellites will remain in orbit for a long, long time, eventually becoming a part of space debris.

 

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Why do wildfires turn the skies orange-red?

News about the wildfires in San Francisco, U.S. dominated headlines in the first weeks of September 2020. The fires were raging, and the damage that went along with it was huge. And then, one morning, residents of the famed San Francisco Bay Area woke up to skies that were orange and red.

Not apocalypse

While those on social media quickly snapped pictures and captioned them in many ways, U.S.’ National Weather Service (NWS) and NASA tried to reassure people that apocalypse hadn’t arrived. And how did they do this? By explaining the science behind the phenomenon of course.

It was pretty clear to almost everyone that the skies’ strange hues were the result of the wildfire. What wasn’t well-known, however, was how exactly this was happening.

NWS went about their explanation by tweeting a picture of a satellite image that showed a thick layer of smoke above California. This smoke was filtering the energy coming from the sun. as a result, the temperatures were much cooler and the dark and dreary skies were the product of the skies shifting towards the red end of the spectrum.

Smoke blocks shorter wavelengths

NASA helped by going into more detail. They added that smoke particles block sunlight’s shorter wavelength colours – yellow, blue and green. They do, however, allow the longer wavelengths to pass through. As red and orange have longer wavelengths, they pass through the smoke and the skies therefore appear in these colours.

 

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That’s some SMART-1 work!

Launched on September 27, 2003, the lunar probe named SMART-1 was the European Space Agency’s (ESA) first mission to the moon. Apart from investigating the moon and studying its surface composition, the spacecraft was used to demonstrate techniques pertaining to navigation and mission control. A.S. Ganesh takes a look at the mission and its success

We might have over 200 natural satellites in the solar system, but our own moon is rather special to us. And it has to be, for it is the only one our Earth has. Naturally then, it has been studied extensively – probably only next to the Earth itself among celestial bodies.

While the space race between the U.S. and the Soviet Union in the second half of the 20th Century probably saw the most funds being spent in a single window towards moon missions, it wasn’t the be all and end all. There have been several missions since then, and there will be many more as well, that will have our moon as its target. Its position – both in terms of importance and in terms of space – make it an ideal destination for testing out new technologies as well.

Missions of all scales

The ESA prides itself in having a science programme that encompasses missions of all scales and sizes. The SMART – short for Small Missions for Advanced Research in Technology – programme was envisioned to cater to small relatively low-cast missions. One such mission that looked to test solar-electric propulsion and other deep space technologies was launched on September 27, 2003. Its destination, as you might have rightly guessed, was the moon.

With a French-built Hall effect thruster derived from a Russian ion propulsion system, SMART-1 was European in almost every sense, even before it became the first European spacecraft to enter orbit around the moon. The thruster, which used a xenon propellant, generated just enough thrust – comparable to the weight of a postcard. Solar arrays powered the engine which generated the power needed for the ion engines.

Slowly expanding orbit

Following its launch, it was put in a geostationary transfer orbit. From here, SMART-1 used its electric propulsion system for a hugely efficient mission profile. Spinning slowly, the spacecraft moved onto higher and higher elliptical orbits. With mission controllers in Darmstadt, Germany forcing calculated, repeated burns of the ion engine, the spacecraft’s spiral orbit expanded step by step.

When SMART-1 was around 2,00,000 km out from Earth, the influence of the moon’s gravity started increasing. By November 2004, the spacecraft had reached a point where the moon’s gravitational force was dominant.

Closer views, better data

The ion engines were still fired gradually, even after SMART-1 attained a polar orbit around the moon. This allowed the spacecraft to now decrease the orbit and hence achieve significantly better and closer views of the lunar surface.

During its time orbiting the moon, SMART-1 improved on data returned from various previous missions to the moon. It studied lunar topography, learnt more about the moon’s surface texture and also mapped the minerals’ surface distribution.

Mission extended

Even though the mission was designed to end in August 2005, it was extended further with new plans for a lunar impact in 2006. Having exhausted the propellant, the spacecraft’s ion engine was fired one last time in September 2005, after which it was in a natural orbit based on the gravitational effects of the moon, Earth and sun, with occasional altitude control. SMART-1’s ion engine had fired for over 4,900 hours, a record at that time for an engine of this type.

As per the revised plan, the spacecraft crashed onto the moon’s surface on September 3, 2006. Earth-based telescopes observed the impact, which produced a dust cloud. The near three-year existence of SMART-1 not only confirmed technical competence, but also provided valuable scientific insights about our moon.

 

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Which is the closest exoplanet to Earth?

The nearest exoplanet discovered so far orbits the star Proxima Centauri, located 4.2 light-years from our planet.

Proxima Centauri is only 4.2 light-years away. This is still tens of thousands of years by rocket travel, but only a hop, skip and a jump away in cosmic terms. If there were a star closer than Proxima, we would have found it by now. Without any closer stars, astronomers don’t expect to find any closer planets.

There is always the chance of a rogue planet existing closer than Proxima. Rogue planets are those that escaped their star systems and now travel the galaxy solo. But while astronomers think rogue planets are reasonably common, it’s unlikely one would lurk quite that close.

The research team studied Proxima b using the Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, or ESPRESSO for short.  ESPRESSO is a Swiss spectrograph that is currently mounted on the European Southern Observatory’s (ESO) Very Large Telescope in Chile. Spectrographs observe objects and split the light coming from those objects into the wavelengths that make it up so that researchers can study the object in closer detail. 

 

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In 2009 NASA launched which mission specifically to look for and detect exoplanets?

The Kepler space telescope is a retired space telescope launched by NASA to discover Earth-size planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched on March 7, 2009, into an Earth-trailing heliocentric orbit. 

Kepler discovered 2,682 exoplanets during its tenure and there are more than 2,900 candidate planets awaiting confirmation — history suggests most of those are the real deal. The mission continued well beyond its scheduled end date, although problems with pointing in 2013 forced mission managers to create a K2 mission in which Kepler swings its view to different spots of the sky.

In the early years of exoplanet hunting, astronomers were best able to find huge gas giants — Jupiter’s size and larger — that were lurking close to their parent star. The addition of Kepler (as well as more sophisticated planet-hunting from the ground) means that more “super-Earths” have been found, or planets that are just slightly larger than Earth but have a rocky surface. Kepler’s finds also allow astronomers to begin grouping exoplanets into types, which helps with understanding their origins.

Kepler’s major achievement was discovering the sheer variety of planetary systems that are out there. Planet systems can exist in compact arrangements within the confines of the equivalent of Mercury’s orbit. They can even orbit around two stars, much like Tatooine in the Star Wars universe. And in an exciting find for those seeking life beyond Earth, the telescope revealed that small, rocky planets similar to Earth are more common than larger gas giants such as Jupiter.

 

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