Chandra’s Look at Kes 75

NASA: Scientists have confirmed the identity of the youngest known pulsar in the Milky Way galaxy using data from NASA’s Chandra X-ray Observatory. This result could provide astronomers new information about how some stars end their lives.

After some massive stars run out of nuclear fuel, then collapse and explode as supernovas, they leave behind dense stellar nuggets called “neutron stars”. Rapidly rotating and highly magnetized neutron stars produce a lighthouse-like beam of radiation that astronomers detect as pulses as the pulsar’s rotation sweeps the beam across the sky.

Since Jocelyn Bell Burnell, Anthony Hewish, and their colleagues first discovered pulsars through their radio emission in the 1960s, over 2,000 of these exotic objects have been identified. However, many mysteries about pulsars remain, including their diverse range of behaviors and the nature of stars that form them.

New data from Chandra are helping address some of those questions. A team of astronomers has confirmed that the supernova remnant Kes 75, located about 19,000 light years from Earth, contains the youngest known pulsar in the Milky Way galaxy.

The rapid rotation and strong magnetic field of the pulsar have generated a wind of energetic matter and antimatter particles that flow away from the pulsar at near the speed of light . This pulsar wind has created a large, magnetized bubble of high-energy particles called a pulsar wind nebula, seen as the blue region surrounding the pulsar.

In this composite image of Kes 75, high-energy X-rays observed by Chandra are colored blue and highlight the pulsar wind nebula surrounding the pulsar, while lower-energy X-rays appear purple and show the debris from the explosion. A Sloan Digital Sky Survey optical image reveals stars in the field.

The Chandra data taken in 2000, 2006, 2009, and 2016 show changes in the pulsar wind nebula with time. Between 2000 and 2016, the Chandra observations reveal that the outer edge of the pulsar wind nebula is expanding at a remarkable 1 million meters per second, or over 2 million miles per hour.

This high speed may be due to the pulsar wind nebula expanding into a relatively low-density environment. Specifically, astronomers suggest it is expanding into a gaseous bubble blown by radioactive nickel formed in the explosion and ejected as the star exploded. This nickel also powered the supernova light, as it decayed into diffuse iron gas that filled the bubble. If so, this gives astronomers insight into the very heart of the exploding star and the elements it created.

The expansion rate also tells astronomers that Kes 75 exploded about five centuries ago as seen from Earth. (The object is some 19,000 light years away, but astronomers refer to when its light would have arrived at Earth.) Unlike other supernova remnants from this era such as Tycho and Kepler, there is no known evidence from historical records that the explosion that created Kes 75 was observed.

Why wasn’t Kes 75 seen from Earth? The Chandra observations along with previous ones from other telescopes indicate that the interstellar dust and gas that fill our Galaxy are very dense in the direction of the doomed star. This would have rendered it too dim to be seen from Earth several centuries ago.

The brightness of the pulsar wind nebula has decreased by 10% from 2000 to 2016, mainly concentrated in the northern area, with a 30% decrease in a bright knot. The rapid changes observed in the Kes 75 pulsar wind nebula, as well as its unusual structure, point to the need for more sophisticated models of the evolution of pulsar wind nebulas.

A paper describing these results appeared in The Astrophysical Journal and is available online. The authors are Stephen Reynolds, Kazimierz Borokowski, and Peter Gwynne from North Carolina State University. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

Image credit: X-ray: NASA/CXC/NCSU/S. Reynolds; Optical: PanSTARRS

Curious Tales of Switching Brains

The rover Curiosity is having issues with saving data to the main computer so they are going to “switch brains” that is, they are going to activate the redundant computer. While this switch has been done before on the rover it is still a very challenging process, especially considering the rover is nearly 107.5 million km / 66.8 million miles away and the complexity of the issues they are troubleshooting. It just shows what a capable and adaptable group the rover team is. Anyway. . .

The image (thanks NASA/JPL-Caltech) is from 15 June 2018, before the sandstorm.

NASA: Engineers at NASA’s Jet Propulsion Laboratory in Pasadena, California, this week commanded the agency’s Curiosity rover to switch to its second computer. The switch will enable engineers to do a detailed diagnosis of a technical issue that has prevented the rover’s active computer from storing science and some key engineering data since Sept. 15.

Like many NASA spacecraft, Curiosity was designed with two, redundant computers — in this case, referred to as a Side-A and a Side-B computer — so that it can continue operations if one experiences a glitch. After reviewing several options, JPL engineers recommended that the rover switch from Side B to Side A, the computer the rover used initially after landing.

The rover continues to send limited engineering data stored in short-term memory when it connects to a relay orbiter. It is otherwise healthy and receiving commands. But whatever is preventing Curiosity from storing science data in long-term memory is also preventing the storage of the rover’s event records, a journal of all its actions that engineers need in order to make a diagnosis. The computer swap will allow data and event records to be stored on the Side-A computer.

Side A experienced hardware and software issues over five years ago on sol 200 of the mission, leaving the rover uncommandable and running down its battery. At that time, the team successfully switched to Side B. Engineers have since diagnosed and quarantined the part of Side A’s memory that was affected so that computer is again available to support the mission.

“At this point, we’re confident we’ll be getting back to full operations, but it’s too early to say how soon,” said Steven Lee of JPL, Curiosity’s deputy project manager. “We are operating on Side A starting today, but it could take us time to fully understand the root cause of the issue and devise workarounds for the memory on Side B.

“We spent the last week checking out Side A and preparing it for the swap,” Lee said. “It’s certainly possible to run the mission on the Side-A computer if we really need to. But our plan is to switch back to Side B as soon as we can fix the problem to utilize its larger memory size.”

Launch Pad Water Test

Testing a newly modified Ignition Overpressure Protection and Sound Suppression water deluge system at Kennedy Space Center’s Launch Pad 39B. The system mitigates the energy and heat during launch.

The system “dumped” about 450,000 gallons of water over the mobile launcher and flame deflector, the spectacular fountains shot water around 33 meters / 100 feet into the air.

Perhaps in the future NASA will produce a video of the pump-side of the system – I’d like to see those pumps.

Thanks to NASA and the Kennedy Space Center

BepiColumbo Launch – REPLAY

Here’s a replay of the launch and events leading up to it. Very good video, if you are in a hurry skip ahead to the 39 minute mark to see the launch and I will put up a shorter version.

So BepiColumbo is on the way to Mercury, but there is a long way to go so my admonition stays the same:
Good Luck BepiColumbo!!

Atlas V 551 with AHEF-4 – REPLAY

Here is a replay of the Atlas V launch with the AEHF-4 satellite going into orbit.

The AEHF-4 (Advanced Extremely High Frequency) is one of the US Air Force’s communications satellites.

Coming up: BEPICOLUMBO! Very early tomorrow or tonight for North American viewers and points west.

Coverage set to begin at 01:45 UTC on 20 Oct // 21:45 EST on Oct 19 for North America

Where to Land the Mars2020 Rover

This should be the week we find out where the Mars2020 rover will land when it gets to Mars. Not a secret, the final decision has not been made, more about that in a second. Have a look at this artists concept (thanks NASA) – NOW THAT’S A ROVER!

NASA: Hundreds of scientists and Mars-exploration enthusiasts will convene in a hotel ballroom just north of Los Angeles later this week to present, discuss and deliberate the future landing site for NASA’s next Red Planet rover – Mars 2020. The three-day workshop is the fourth and final in a series designed to ensure NASA receives the broadest range of data and opinion from the scientific community before the agency chooses where to send the new rover.

The Mars 2020 mission is tasked with not only seeking signs of habitable conditions on Mars in the ancient past, but also searching for signs of past microbial life. The landing site for Mars 2020 is of great interest to the planetary community because, among the rover’s new medley of science gear for surface exploration, it carries a sample system that will collect rock and soil samples and set them aside in a “cache” on the surface of Mars. A future mission could potentially return these samples to Earth. The next Mars landing, after Mars 2020, could very well be a vehicle that would retrieve these Mars 2020 samples.

“The Mars 2020 landing site could set the stage for Mars exploration for the next decade,” said Thomas Zurbuchen, Associate Administrator of the Science Mission Directorate at NASA Headquarters in Washington. “I’m looking forward to the spirited debate and critical input from the science and engineering community. Whichever landing site is ultimately chosen, it may hold the very first batch of Mars soil that humans touch.”

The workshop begins with an opening address by the lead scientist for NASA’s Mars Exploration Program, Michael Meyer. After project status, engineering constraints, and site-assessment criteria are discussed come the presentations. Fair warning: Expect plenty of technical jargon as terms like biosignatures, geochemical conditions, impact deformation, biogenetic potential, olivine lithologies, and serpentinization and its astrobiological potential roll off presenters’ tongues.

“We have been doing these workshops in support of 2020 landing site selection since 2014,” said Matt Golombek, cochair of the Mars Landing Site Steering Committee from NASA’s Jet Propulsion Laboratory in Pasadena, California. “At our first workshop, we started with about 30 candidate landing sites, and after additional orbital imaging and a second landing site workshop, we had a recommendation of eight sites to move forward for further evaluation. There were so many great locations to choose from, the whittling-down process was tough. This time around, with four finalists, it promises to be even more difficult. Each site has its own intriguing science potential and knowledgeable advocates.”

Champions for four landing options will take their turn at the podium, presenting and defending their favorite parcel on the Red Planet. It is one more site than was expected after the completion of the third workshop, in 2017, where three locations on Mars were recommended for consideration – Columbia Hills, Jezero Crater and Northeast Syrtis.

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Second Space Telescope in Safe-Mode

Another space telescope went into safe-mode due to a gyroscope issue. In this case the Chandra X-ray Observatory went into safe-mode on 10 October, 5-days after Hubble.

Unlike Hubble this particular problem as been resolved and the telescope was put back into normal operation.

Image: Chandra / NASA

 

The NASA press release included the process on going into safe-mode in this particular case.

From NASA:   The cause of Chandra’s safe mode on October 10 has now been understood and the Operations team has successfully returned the spacecraft to its normal pointing mode. The safe mode was caused by a glitch in one of Chandra’s gyroscopes resulting in a 3-second period of bad data that in turn led the on-board computer to calculate an incorrect value for the spacecraft momentum. The erroneous momentum indication then triggered the safe mode.

The team has completed plans to switch gyroscopes and place the gyroscope that experienced the glitch in reserve. Once configured with a series of pre-tested flight software patches, the team will return Chandra to science operations which are expected to commence by the end of this week.
At approximately 9:55 a.m. EDT on Oct. 10, 2018, NASA’s Chandra X-ray Observatory entered safe mode, in which the observatory is put into a safe configuration, critical hardware is swapped to back-up units, the spacecraft points so that the solar panels get maximum sunlight, and the mirrors point away from the Sun. Analysis of available data indicates the transition to safe mode was normal behavior for such an event. All systems functioned as expected and the scientific instruments are safe. The cause of the safe mode transition (possibly involving a gyroscope) is under investigation, and we will post more information when it becomes available.

Chandra is 19 years old, which is well beyond the original design lifetime of 5 years. In 2001, NASA extended its lifetime to 10 years. It is now well into its extended mission and is expected to continue carrying out forefront science for many years to come.