Universe Today

August 3, 2014December 23, 2015 by Ken Kremer

Rosetta Orbiter less than 500 Kilometers from Comet 67P Following Penultimate Trajectory Burn

NAVCAM camera image taken on 2 August 2014 from a distance of about 500 kilometers from comet 67P/Churyumov-Gerasimenko. Credits: ESA/Rosetta/NAVCAM

The Rosetta comet chaser is currently less than 500 kilometers (300 miles) from its target destination, Comet 67P/Churyumov-Gerasimenko following today’s (Aug. 3) successful completion of the spacecraft’s critically important penultimate trajectory burn, just three days before its history making arrival at the comet on Aug. 6.

The European Space Agency’s (ESA) 1.3 Billion euro Rosetta spacecraft is now under three days away from becoming Earth’s first probe ever to rendezvous with and enter orbit around a comet after a decade long hunt of 6.4 billion kilometers (4 Billion miles) through interplanetary space. The gap is narrowing with each passing second.

The last trajectory firing is set for Aug. 6. Altogether the final pair of trajectory burns will reduce the spacecrafts speed by some 3.5 meters per second (m/s) with respect to the comet which is traveling at 55,000 kilometers per hour (kph).

The probes latest Navcam camera image shot on Aug. 2, 2014 from a distance of about 500 kilometers from comet 67P/Churyumov-Gerasimenko shows exquisite detail of the rubber ducky shaped body tumbling end over end. See above.

See below our mosaic of navcam camera approach images of the nucleus captured over the past week and a half of the mysterious two lobed comet, merged at a bright band in between.

In November 2014, the Rosetta mothership will attempt another historic first when it deploys the Philae science lander from an altitude of just 1 or 2 kilometers for the first ever attempt to land on a comet’s nucleus. The lander will fire harpoons to anchor itself to the 4 kilometer wide (2.5 mile) comet’s surface.

Together, Rosetta and Philae will investigate how the pristine frozen comet composed of ice and rock is transformed by the warmth of the Sun. They will also search for organic molecules, nucleic acids and amino acids, the building blocks for life as we know it.

Did life on Earth begin with the help of comet seeding? That’s a question the Rosetta science team seeks to help answer.

Today’s early morning thruster firing, officially known as the Close Approach Trajectory – pre-Insertion (CATP) burn, began as scheduled at 11:00 CEST (09:00 GMT) and was due to last for about 13 minutes and 12 seconds and bleed off some 3.2 m/s of spacecraft speed.

Although it ended a few seconds early, ESA reports that the CATP burn went well as engineers monitored the spacecraft communications at the European Space Operations Centre (ESOC), in Darmstadt, Germany via the agency’s 35 meter deep-space tracking station in New Norcia, Australia.

“All looks good,” says Rosetta Spacecraft Operations Manager Sylvain Lodiot, according to an ESA operations tweet.

CATP is part of the final series of ten orbit correction maneuvers (OCM’s) that culminates with the final thruster firing slated for Aug. 6 dubbed the Close Approach Trajectory – Insertion (CATI) burn.

“The CATI burn will reduce the relative velocity to about 1 m/s,” says Lodiot. That’s about equivalent to human walking speed.

The CATI orbit insertion firing will slow Rosetta to essentially the same speed as a comet and place it in orbit at an initial stand-off distance of about 100 kilometers (62 miles).

Rosetta will initially be travelling in a series of 100 kilometer-long triangular arcs while firings thrusters at each apex. Further engine firings will gradually lower Rosetta’s altitude about Comet 67P until the spacecraft is captured by the comet’s gravity.

After catching up with the comet Rosetta will slightly overtake and enter orbit from the ‘front’ of the comet as both the spacecraft and 67P/CG move along their orbits around the Sun. Rosetta will carry out a complex series of manoeuvres to reduce the separation between the spacecraft and comet from around 100 km to 25-30 km. From this close orbit, detailed mapping will allow scientists to determine the landing site for the mission’s Philae lander. Immediately prior to the deployment of Philae in November, Rosetta will come to within just 2.5 km of the comet’s nucleus. This animation is not to scale; Rosetta’s solar arrays span 32 m, and the comet is approximately 4 km wide. Credit: ESA–C. Carreau

“All systems on the spacecraft are performing well and the entire team is looking forward to a smooth arrival,” says Lodiot.

It will study and map the wanderer composed of primordial ice, rock, dust and more and search for a suitable landing site for Philae.

The one-way signal time from Earth to Rosetta and Comet 67P is currently 22 minutes and 27 seconds as both loop around the Sun at a distance of some 555 million kilometres away from the Sun at this time. The short period comet is located between the orbits of Jupiter and Mars.

Rosetta will escort Comet 67P as they journey together inwards around the sun and then travel back out towards Jupiter’s orbit and investigate the physical properties and chemical composition of the comets nucleus and coma of ice and dust for some 17 months.

Rosetta was launched on 2 March 2004 on an Ariane 5 G+ rocket from Europe’s spaceport in Kourou, French Guiana.

You can watch Rosetta’s Aug. 6 orbital arrival live from 10:45-11:45 CEST via a livestream transmission from ESA’s spacecraft operations centre in Darmstadt, Germany.

Stay tuned here for Ken’s continuing Rosetta, Curiosity, Opportunity, Orion, SpaceX, Boeing, Orbital Sciences, commercial space, MAVEN, MOM, Mars and more Earth and Planetary science and human spaceflight news.

Ken Kremer

August 3, 2014December 23, 2015 by Ken Kremer

Ranger 7 Takes 1st Image of the Moon by a US Spacecraft 50 Years Ago – July 31, 1964

Ranger 7 took this image, the first picture of the Moon by a U.S. spacecraft, on 31 July 1964 at 13:09 UT (9:09 AM EDT) about 17 minutes before impacting the lunar surface. Credit: NASA/JPL-Caltech

As we remember the 45th anniversary of Earth’s historic 1st manned lunar landing last week by America’s Apollo 11 crew of Neil Armstrong and Buzz Aldrin on July 20, 1969, it’s likewise well worth recalling NASA’s pioneering and historic unmanned robotic mission Ranger 7 – that led the way to the Moon almost exactly 5 years earlier and that paved the path for the eventual 1st human footsteps on another celestial body.

Indeed the first critical robotic step to the manned landings was successfully taken when NASA’s unmanned Ranger 7 probe captured the first image of the Moon by a U.S. spacecraft 50 Years ago on July 31, 1964.

Ranger 7 took the milestone maiden picture of the Moon by an American spacecraft, on 31 July 1964, shown above, at 13:09 GMT (9:09 AM EDT) about 17 minutes before impacting the lunar surface on a suicide dive.

The history making image was taken at an altitude of 2110 kilometers and is centered at 13 S, 10 W and covers about 360 kilometers from top to bottom. The large Alphonsus crater is at center right and 108 km in diameter. Ptolemaeus crater is above and Arzachel is below.

Ranger 7 impacted out of view of the lead image, off to the left of the upper left corner.

“It looks as though this particular shot has been indeed a textbook operation,” William H. Pickering, the director of JPL during the mission, said at the time.

Guericke Crater as seen by Ranger 7. Ranger 7 B-camera image of Guericke crater (11.5 S, 14.1 W, diameter 63 km) taken from a distance of 1335 km. The dark flat floor of Mare Nubium dominates most of the image, which was taken 8.5 minutes before Ranger 7 impacted the Moon on 31 July 1964. The frame is about 230 km across and north is at 12:30. The impact site is off the frame to the left. Credit: NASA/JPL-Caltech — Guericke Crater as seen by Ranger 7
Ranger 7 B-camera image of Guericke crater (11.5 S, 14.1 W, diameter 63 km) taken from a distance of 1335 km. The dark flat floor of Mare Nubium dominates most of the image, which was taken 8.5 minutes before Ranger 7 impacted the Moon on 31 July 1964. The frame is about 230 km across and north is at 12:30. The impact site is off the frame to the left. Credit: NASA/JPL-Caltech

The purpose of NASA’s robotic Ranger program was to take high-quality pictures of the Moon and transmit them back to Earth in real time before being decimated on impact.

NASA Ranger 7 spacecraft. Credit: NASA/JPL-Caltech

The priceless pictures would be used for science investigations as well as to search for suitable landing sites for NASA’s then planned Apollo manned Moon landers.

It’s hard to conceive now, but 5 decades ago at the dawn of the Space Age no one knew what the surface of the Moon was really like. There were vigorous debates back then on whether it was even hard or soft. Was it firm? Would a landed spacecraft or human astronaut sink?

Last Ranger 7 images taken before impact on the Moon. They were taken by the number 1 and 3 P-channel cameras at 0.39 and 0.19 s before impact from an altitude of 1070 and 519 meters, respectively. The pictures are cut off because the spacecraft impacted the surface before completing the transmission. The top image was taken by the P3 camera and the bottom image by P1. The P3 image is about 25 m across. North is at 12:30 for both images. The impact occurred on 31 July 1964 at 13:25:48.82 UT. Credit: Credit: NASA/JPL-Caltech — Last Ranger 7 images taken before impact on the Moon. They were taken by the number 1 and 3 P-channel cameras at 0.39 and 0.19 s before impact from an altitude of 1070 and 519 meters, respectively. The pictures are cut off because the spacecraft impacted the surface before completing the transmission. The top image was taken by the P3 camera and the bottom image by P1. The P3 image is about 25 m across. North is at 12:30 for both images. The impact occurred on 31 July 1964 at 13:25:48.82 UT. Credit: NASA/JPL-Caltech

Altogether the probe took 4,308 excellent quality pictures during its final 17 minutes before crashing into the Moon at 13:26 GMT (9:26 p.m. EDT) in an area between Mare Nubium and Oceanus Procellarum at a spot subsequently named Mare Cognitum at 10.63 S latitude, 20.60 W longitude.

The final image from Ranger 7 shown herein had a resolution of 0.5 meter/pixel.

Ranger 7 was launched atop an Atlas Agena B rocket on 28 July 1964 from what was then known as Cape Kennedy and smashed into our nearest neighbor after 68.6 hours of flight at a velocity of 2.62 km/s (1.62 miles per second).

The 365.7 kilogram (806 lb) vehicle was 4.5 m wide and stood 3.6 m (11 ft) tall and was the Block 3 version of the Ranger spacecraft. It was powered by a pair of 1.5 m long solar panels and was equipped with a science payload of six television vidicon cameras transmitting data via the pointable high gain antennae mounted at the base.

Ranger 7 was the first successful mission in the Ranger series. The flight was entirely successful and was followed by Ranger’s 8 and 9. They were built by NASA’s Jet Propulsion Laboratory, Pasadena, California.

Here’s a short 1964 documentary chronicling Ranger 7 titled “Lunar Bridgehead” that truly harkens back to the 1950s and 1960s and sci fi movies of the time. No wonder since that’s when it was produced.

Video Caption. This 1964 documentary titled “Lunar Bridgehead produced by NASA’s Jet Propulsion Laboratory, Pasadena, California, chronicles the moments leading up to and following the Ranger 7 mission’s lunar impact 50 years ago. Credit: NASA/JPL-Caltech

During the 1960’s NASA implemented an ambitions three pronged strategy of robotic missions – including Ranger, Lunar Orbiter and Surveyor – that imaged the Moon and studied it’s physical and chemical properties and supported and enabled the Apollo program and led directly to Neil Armstrong stepping onto the alien lunar landscape.

Three members of the Ranger 7 television experiment team stand near a scale model and lunar globe at NASA’s Jet Propulsion Laboratory (JPL). From left: Ewen Whitaker, Dr. Gerard Kuiper, and Ray Heacock. Kuiper was the director of the Lunar and Planetary Laboratory (LPL) at the University of Arizona. Whitaker was a research associate at LPL. Heacock was the Lunar and Planetary Instruments section chief at JPL. Credit: NASA/JPL-Caltech

Read more about pathfinding space missions in my earlier space history story about Mariner 10 – the first space probe to ever carry out a planetary gravity assist maneuver used to alter its speed and trajectory – in order to reach another celestial body – here.

Read my 45th Apollo 11 anniversary articles here:

Apollo 11 Splashdown 45 Years Ago on July 24, 1969 Concludes 1st Moon Landing Mission – Gallery

Historic Human Spaceflight Facility at Kennedy Renamed in Honor of Neil Armstrong – 1st Man on the Moon

Apollo 11 Moon Landing 45 Years Ago on July 20, 1969: Relive the Moment! – With an Image Gallery and Watch the Restored EVA Here

Book Review: Neil Armstrong – A Life of Flight by Jay Barbree

Stay tuned here for Ken’s Earth & Planetary science and human spaceflight news.

Ken Kremer

Liftoff of Ranger 7 on July 28, 1964 from Cape Kennedy at Launch Complex 12. Credit: NASA

Neil Armstrong and Buzz Aldrin plant the US flag on the Lunar Surface during 1st human moonwalk in history 45 years ago on July 20, 1969 during Apollo 1l mission. Credit: NASA — Neil Armstrong and Buzz Aldrin plant the US flag on the Lunar Surface during 1st human moonwalk in history 45 years ago on July 20, 1969 during Apollo 11 mission. Credit: NASA

August 3, 2014December 23, 2015 by Bob King

Getting to Know Comet 67P/Churyumov-Gerasimenko

Comet 67P/Churyumov-Gerasimenko at 621 miles (1,000 km) on August 1. Wow! Look at that richly-textured surface. This photo has higher resolution than previous images because it was taken with Rosetta's narrow angle camera. The black spot is an artifact. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

We’re finally getting to know the icy nucleus behind comet 67P/Churyumov-Gerasimenko. For all the wonder that comets evoke, we on Earth never see directly what whips up the coma and tail. Even professional telescopes can’t burrow through the dust and vapor cloaking the nucleus to distinguish the clear outline of a comet’s heart. The only way to see one is to fly a camera there.

Asteroids we've seen up close show cratered surfaces similar to yet different from much of the cratering on comets. Credit: — Asteroids we’ve seen up close show cratered surfaces similar to yet different from much of the cratering so far seen on comets. Not to scale. Credit: NASA except for Steins (ESA)

Rosetta took 10 years to reach 67P/C-G, a craggy, boot-shaped body that resembles an asteroid in appearance but with key differences. Asteroids shown in close up photos often display typical bowl-shaped impact craters. From the photos to date, 67P/C-G’s ‘craters’ look shallow and flat in comparison. Were they impacts smoothed by ice flows over time? Did some of the dust and vapor spewed by the comet settle back on the surface to partially bury and soften the landscape?

Comet 81P/Wild 2 photographed during the Stardust mission in 2004. Wild 2 measures 1.03 x 1.24 x 1.71 miles and goes around the sun once every 6.4 years. Its surfaced is riddled with flat-bottomed craters, some of which may also be gas vents from vaporized ice. Credit: NASA — Comet 81P/Wild 2 photographed during the Stardust mission in 2004. Wild 2 measures 1.03 x 1.24 x 1.71 miles and goes around the sun once every 6.4 years. Its surfaced is riddled with flat-bottomed depressions some of which may also vent gas from vaporizing ice. Click for more 81P/Wild 2 photos. Credit: NASA

While 67P is doubtless its own comet, it does share certain similarities with Comet 81P/Wild including at least a few crater-like depressions seen during NASA’s Stardust mission. In January 2004, the spacecraft gathered photos, measurements and dust samples during its brief flyby of the nucleus. Photos reveal pinnacles, flat-bottomed depressions and bright plumes or jets of vaporizing ice.

Some of the comets we've seen close up through the eyes of visiting spacecraft. Credit: NASA — Some of the comets we’ve seen close up through the eyes of visiting spacecraft. Credit: NASA

In a 2004 paper by Donald Brownlee and team, the group experimentally reproduced the flat-floored craters by firing projectiles into resin-coated sand baked a bit to make it cohere. Their results suggest the craters formed from impacts in loosely compacted material under the low-gravity conditions typical of small objects like comets. To quote the paper: “Most disrupted material stayed inside the cavity and formed a flat-floored deposit and steep cliffs formed the rim.” Icy materials mixed with dust may have also played a role in their appearance and other crater-like depressions called pit-halos.

Speculation isn’t science, so I’ll stop here. So much more data will be streaming in soon, we’ll have our hands full. On Wednesday, August 6th, Rosetta will enter orbit around the nucleus and begin detailed studies that will continue through December 2015. Studying the new pictures now arriving daily, I’m struck by the dual nature of comets. We see an ancient landscape and yet one that looks strangely contemporary as the sun vaporizes ice, reworking the terrain like a child molding clay.

Comet 67P/Churyumov-Gerasimenko is well-placed in the mid-summer sky in Sagittarius but impossibly faint to see visually. Dave Herald's photo taken on August 21, 2014 shows only a tiny fuzz of magnitude +21. Credits: Background: Stellarium; David Herald — Comet 67P/Churyumov-Gerasimenko is well-placed in the mid-summer sky in Sagittarius but impossibly faint visually. Dave Herald’s photo taken on August 21, 2014 shows only a tiny fuzz of magnitude +21. Credits: Dave Herald; Stellarium

August 1, 2014December 23, 2015 by Ken Kremer

Rosetta Closing in on Comet 67P/Churyumov-Gerasimenko after Decade Long Chase

ESA’s Rosetta Spacecraft nears final approach to Comet 67P/Churyumov-Gerasimenko in late July 2014. This collage of imagery from Rosetta combines Navcam camera images at right taken nearing final approach from July 25 to July 31, 2014, with OSIRIS wide angle camera image at left of comet’s coma on July 25 from a distance of around 3000 km. On July 31 Rosetta had approached to within 1327 km. Images to scale and contrast enhanced to show further detail. Credit: ESA/Rosetta/NAVCAM/OSIRIS/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Collage/Processing: Marco Di Lorenzo/Ken Kremer – kenkremer.com
Story updated[/caption]

The European Space Agency’s (ESA) Rosetta spacecraft is at last rapidly closing in on its target destination, Comet 67P/Churyumov-Gerasimenko, after a decade long chase of 6.4 billion kilometers through interplanetary space. See imagery above and below.

As of today, Friday, August 1, ESA reports that Rosetta has approached the ‘rubber ducky looking’ comet to within a distance of less than 1153 kilometers. That distance narrows with each passing moment as the speeding robotic probe moves closer and closer to the comet while looping around the sun at about 55,000 kilometers per hour (kph).

Rosetta is now just 5 days away from becoming Earth’s first probe ever to rendezvous and enter orbit around a comet.

See above our image collage of Rosetta nearing final approach with the spacecrafts most recent daily Navcam camera images, all taken within the past week starting on July 25 and including up to the most recently release image snapped on July 31. The navcam images are all to scale to give the sense of the spacecraft approaching the comet and revealing ever greater detail as it grows in apparent size in the cameras field of view. The navcam images were also taken at about the same time of day each day.

The highest resolution navcam image yet of the two lobed comet – merged at a bright band – was taken on July 31 from a distance of 1327 kilometers and published within the past few hours by ESA today, Aug 1. It shows the best view yet of the surface features of the mysterious bright necked wanderer composed of primordial ice, rock, dust and more.

The Navcam collage is combined with an OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) wide angle camera view of the comet and its asymmetric coma of ice and dust snapped on July 25 from a distance of around 3000 km, and with an exposure time of 300 seconds. The OSIRIS image covers an area of about 150 x 150 km (90 mi x 90 mi). The images have been contrast enhanced to bring out more detail.

Scientists speculate that the comets bright neck region could be caused by differences in material or grain size or topological effects.

Rosetta’s history making orbital feat is slated for Aug. 6 following the final short duration orbit insertion burns on Aug. 3 and Aug. 6 to place Rosetta into orbit at an altitude of about 100 kilometers (62 miles) where it will study and map the 4 kilometer wide comet for some 17 months.

The comet rotates around once every 12.4 hours.

Crop from the 31 July processed image of comet 67P/Churyumov-Gerasimenko, to focus on the comet nucleus. Credits: ESA/Rosetta/NAVCAM

“If any glitches in space or on ground had delayed the most recent burns, orbital mechanics dictate that we’d only have had a matter of a few days to fix the problem, re-plan the burn and carry it out, otherwise we run the risk of missing the comet,” says Trevor Morley, a flight dynamics specialist at ESOC.

In November 2014 the Rosetta mothership will deploy the Philae science lander for the first ever attempt to land on a comet’s nucleus using harpoons to anchor itself to the surface while the comet is rotating.

As Rosetta edges closer on its final lap, engineers at mission control at the European Space Operations Centre (ESOC), in Darmstadt, Germany have commanded the probes navigation camera (navcam) to capture daily images while the other science instruments also collect measurements analyzing the comets physical characteristics and chemical composition in detail.

ESA’s Rosetta Spacecraft nears final approach to Comet 67P/Churyumov-Gerasimenko in late July 2014. This image collage from Rosetta combines Navcam camera images taken nearing final approach from July 25 (3000 km distant) to July 31, 2014 (1327 km distant). Top row shows images as seen by spacecraft. Bottom row shows images rotated to same orientation. Images to scale and contrast enhanced to show further detail. Credit: ESA/Rosetta/NAVCAM. Collage/Processing: Marco Di Lorenzo/Ken Kremer

The probe has already discovered that the comet’s surface temperature is surprisingly warm at –70ºC, which is some 20–30ºC warmer than predicted. This indicates the surface is too hot to be covered in ice and must instead have a dark, dusty crust, says ESA.

Comet 67P/Churyumov-Gerasimenko is a short period comet some 555 million kilometres from the Sun at this time, about three times further away than Earth and located between the orbits of Jupiter and Mars.

You can watch the Aug. 6 orbital arrival live via a livestream transmission from ESA’s spacecraft operations centre in Darmstadt, Germany.

While you were reading this the gap between the comet and Rosetta closed to less than 1000 kilometers!

The coma of Rosetta's target comet as seen with the OSIRIS wide-angle camera. The image spans 150 km and was taken on 25 July 2014 with an exposure time of 330 seconds. The greyscale relates to the particle density in the coma, with highest density close to the nucleus, becoming more diffuse further away. The hazy circular structure on the right is an artefact. The nucleus is also overexposured. The specks and the streaks in the background are attributed to background stars and cosmic rays. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA — The coma of Rosetta’s target comet as seen with the OSIRIS wide-angle camera. The image spans 150 km and was taken on 25 July 2014 with an exposure time of 330 seconds. The greyscale relates to the particle density in the coma, with highest density close to the nucleus, becoming more diffuse further away. The hazy circular structure on the right is an artefact. The nucleus is also overexposured. The specks and the streaks in the background are attributed to background stars and cosmic rays. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Stay tuned here for Ken’s continuing Curiosity, Opportunity, Orion, SpaceX, Boeing, Orbital Sciences, commercial space, MAVEN, MOM, Mars and more Earth and Planetary science and human spaceflight news.

Ken Kremer

Birthday cakes at @ESA_Rosetta Flight Dynamics are taking strange binary shapes these days... #ESOC. Credit: ESA — Birthday cakes at @ESA_Rosetta Flight Dynamics are taking strange binary shapes these days… #ESOC. Credit: ESA

August 1, 2014December 23, 2015 by Elizabeth Howell

‘Explore Mars’ Group Wants To Build Instrument Seeking Subsurface Red Planet Life

Artist's concept of the proposed "ExoLance" instrument that Explore Mars would have burrow beneath the Red Planet's surface for life. Credit: ExoLance/Indiegogo/YouTube (screenshot)

Not-for-profit group Explore Mars has a new IndieGoGo campaign that could see an instrument, ExoLance, head to the Red Planet to burrow for subsurface life. The first stage will be to raise money to build the prototype and then test it, within 12-14 months of finishing the fundraising.

No launch date for this mission has been announced, but the group says that will be determined after testing is finished and a launch provider can be found.

“Explore Mars has devised a simple system capable of being delivered to the Martian surface to detect microorganisms living on or under the surface,” the campaign page states.

“ExoLance leverages a delivery system that was originally designed for military purposes. As each small, lightweight penetrator probe (“arrow”) impacts the surface, it leaves behind a radio transmitter at the surface to communicate with an orbiter, and then kinetically burrows to emplace a life-detection experiment one to two meters below the surface. ExoLance combines the experiments of the 1970s Viking landers and the Curiosity rover with bunker-busting weapons technology.”

The project aims to raise $250,000, but there will be milestone goals available all the way up to $1 million.

August 1, 2014December 23, 2015 by Elizabeth Howell

Companion Planet Could Keep Alien Earths Warm In Old Age: Study

An artist's concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).

People are generally social creatures, and in the case of planets that generally is the case as well. Many of these alien worlds we have discovered are in groups of two or more around their parent star or stars. A new study, however, goes a step further and says that a companion planet could actually save another planet in its old age.

“Planets cool as they age. Over time their molten cores solidify and inner heat-generating activity dwindles, becoming less able to keep the world habitable by regulating carbon dioxide to prevent runaway heating or cooling,” the University of Washington stated.

“But astronomers … have found that for certain planets about the size of our own, the gravitational pull of an outer companion planet could generate enough heat — through a process called tidal heating — to effectively prevent that internal cooling, and extend the inner world’s chance at hosting life.”

The researchers ran computer models finding that tidal heating, which is known to happen on Jupiter’s moons Europa and Io, can also happen in planets the size of Earth that are in non-circular orbits around dwarf stars. An outer planet would keep the orbit from stabilizing in a circle, generating tidal heating and keeping conditions potentially warm enough for life.

The study, led by the University of Arizona’s Christa Van Laerhoven, will be available in the Monthly Notices of the Royal Astronomical Society and is available now in preprint version on Arxiv.

August 1, 2014December 23, 2015 by Elizabeth Howell

Rosetta’s Comet Is Too Hot For Complete Ice Surface, Spacecraft En Route Reveals

Graphic of the instrument on the Rosetta spacecraft that measured the comet's temperature in mid-July 2014. Credit: European Space Agency

Anyone eager for a comet countdown? It’s just a few days now until the Rosetta spacecraft arrives near Comet 67P/Churyumov–Gerasimenko on August 6, and with each passing day more detail becomes visible.

The “rubber duckie”-shaped comet has an average surface temperature of –70 degrees Celsius (-94 degrees Fahrenheit), which is far warmer than scientists expect. At 20 to 30 degrees Celsius (68 to 86 degrees Fahrenheit) warmer than predicted, the scientists say that the comet is too hot to be covered in ice. It must instead of a dark crust.

“This result is very interesting, since it gives us the first clues on the composition and physical properties of the comet’s surface,” stated Fabrizio Capaccioni, principal investigator of the visible, infrared and thermal imaging spectrometer (VIRTIS) that took the measurements.

Capaccioni, who is from Italy’s INAF-IAPS, led a team that took measurements of the comet between July 13 and July 21. What they found was also consistent with the findings from other close-up views of comets, such as 1P/Halley. Observations from afar already revealed that Rosetta had low reflectivity, so this is consistent with those far-off looks.

“This doesn’t exclude the presence of patches of relatively clean ice, however, and very soon, VIRTIS will be able to start generating maps showing the temperature of individual features,” stated Capaccioni.

Source: European Space Agency

July 31, 2014December 23, 2015 by Shannon Hall

Hubble Spots Farthest Lensing Galaxy Yet

Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)

Sometimes there’s a chance alignment — faraway in the universe, where objects are separated by unimaginable distances measured in billions of light-years — when a galaxy cluster in the foreground intersects light from an even more distant object. The conjunction plays visual tricks, where the galaxy cluster acts like a lens, appearing to magnify and bend the distant light.

The rare cosmic alignment can bring the distant universe into view. Now, astronomers have stumbled upon a surprise: they’ve detected the most distant cosmic magnifying glass yet.

Seen above as it looked 9.6 billion years ago, this monster elliptical galaxy breaks the previous record holder by 200 million light-years. It’s bending, distorting and magnifying the distant spiral galaxy, whose light has taken 10.7 billion years to reach Earth.

“When you look more than 9 billion years ago in the early universe, you don’t expect to find this type of galaxy-galaxy lensing at all,” said lead researcher Kim-Vy Tran from Texas A&M University in a Hubble press release.

“Imagine holding a magnifying glass close to you and then moving it much farther away. When you look through a magnifying glass held at arm’s length, the chances that you will see an enlarged object are high. But if you move the magnifying glass across the room, your chances of seeing the magnifying glass nearly perfectly aligned with another object beyond it diminishes.”

The team was studying star formation in data collected by the W. M. Keck Observatory in Hawai’i, when they came across a strong detection of hot hydrogen gas that appeared to arise form a massive, bright elliptical galaxy. It struck the team as odd. Hot hydrogen is a clear sign of star birth, but it was detected in a galaxy that looked far too old to be forming new stars.

“I was very surprised and worried,” Tran recalled. “I thought we had made a major mistake with our observations.”

So Tran dug through archived Hubble images, which revealed a smeared, blue object next to the larger elliptical. It was the clear signature of a gravitational lens.

“We discovered that light from the lensing galaxy and from the background galaxy were blended in the ground-based data, which was confusing us,” said coauthor Ivelina Momcheva of Yale University. “The Keck spectroscopic data hinted that something interesting was going on here, but only with Hubble’s high-resolution spectroscopy were we able to separate the lensing galaxy from the more distant background galaxy and determine that the two were at different distances. The Hubble data also revealed the telltale look of the system, with the foreground lens in the middle, flanked by a bright arc on one side and a faint smudge on the other — both distorted images of the background galaxy. We needed the combination of imaging and spectroscopy to solve the puzzle.”

By gauging the intensity of the background galaxy’s light, the team was able to measure the giant galaxy’s total mass. All in all it weighs 180 billion times more than our Sun. Although this may seem big, it actually weighs four times less than the Milky Way galaxy.

“There are hundreds of lens galaxies that we know about, but almost all of them are relatively nearby, in cosmic terms,” said lead author Kenneth Wong from the Academia Sinica Institute of Astronomy & Astrophysics. “To find a lens as far away as this one is a very special discovery because we can learn about the dark-matter content of galaxies in the distant past. By comparing our analysis of this lens galaxy to the more nearby lenses, we can start to understand how that dark-matter content has evolved over time.”

Interestingly, the lensing galaxy is underweight in terms of its dark-matter content. In the past, astronomers have assumed that dark matter and normal matter build up equally in a galaxy over time. But this galaxy, suggests this is not the case.

The team’s results appeared in the July 10 issue of The Astrophysical Journal Letters and is available online.

July 31, 2014December 23, 2015 by Shannon Hall

Surprise! Classical Novae Produce Gamma Rays

These images show Fermi data centered on each of the four gamma-ray novae observed by the LAT. Colors indicate the number of detected gamma rays with energies greater than 100 million electron volts (blue indicates lowest, yellow highest). Image Credit: NASA/DOE/Fermi LAT Collaboration

In a classical nova, a white dwarf siphons material off a companion star, building up a layer on its surface until the temperature and pressure are so high (a process which can take tens of thousands of years) that its hydrogen begins to undergo nuclear fusion, triggering a runaway reaction that detonates the accumulated gas.

The bright outburst, which releases up to 100,000 times the annual energy output of our Sun, can blaze for months. All the while, the white dwarf remains intact, with the potential of going nova again.

It’s a relatively straightforward picture — as far as complex astrophysics goes. But new observations with NASA’s Fermi Gamma-ray Space Telescope unexpectedly show that three classical novae — V959 Monocerotis 2012, V1324 Scorpii 2012, and V339 Delphini 2013 — and one rare nova, also produce gamma rays, the most energetic form of light.

“There’s a saying that one is a fluke, two is a coincidence, and three is a class, and we’re now at four novae and counting with Fermi,” said lead author Teddy Cheung from the Naval Research Laboratory in a press release.

The first nova detected in gamma rays was V407 Cygni — a rare star system in which a white dwarf interacts with a red giant — in March 2010.

One explanation for the gamma-ray emission is that the blast from the nova hits the hefty wind from the red giant, creating a shock wave that accelerates any charged particles to near the speed of light. These rapid particles, in turn, produce gamma rays.

But the gamma-ray peak follows the optical peak by a couple of days. This likely happens because the material the white dwarf ejects initially blocks the high-energy photons from escaping. So the gamma rays cannot escape until the material expands and thins.

But the later three novae are from systems that don’t have red giants and therefore their winds. There’s nothing for the blast wave to crash into.

“We initially thought of V407 Cygni as a special case because the red giant’s atmosphere is essentially leaking into space, producing a gaseous environment that interacts with the explosion’s blast wave,” said coauthor Steven Shore from the University of Pisa. “But this can’t explain more recent Fermi detections because none of those systems possess red giants.”

In a more typical system it’s likely that the blast creates multiple shock waves that expand into space at slightly different speeds. Faster shocks could blast into slower ones, creating the interaction necessary to produce gamma rays. Although, the team remains unsure if this is the case.

Astronomers estimate that between 20 and 50 novae occur each year in the Milky Way galaxy. Most go undetected, their visible light obscured by intervening dust, and their gamma rays dimmed by distance. Hopefully, future observations of nearby novae will shed light on the mysterious process producing gamma rays.

The results will appear in Science on August 1.

July 31, 2014December 23, 2015 by Ken Kremer

NASA Announces Science Instruments for Mars 2020 Rover Expedition to the Red Planet

An artist concept image of where seven carefully-selected instruments will be located on NASA’s Mars 2020 rover. The instruments will conduct unprecedented science and exploration technology investigations on the Red Planet as never before. Image Credit: NASA

NASA announced the winners of the high stakes science instrument competition to fly aboard the Mars 2020 rover at a briefing held today, Thursday, July 31, at the agency’s headquarters in Washington, D.C.

The 2020 rover’s instruments goals are to search for signs of organic molecules and past life and help pave the way for future human explorers.

Seven carefully-selected payloads were chosen from a total of 58 proposals received in January 2014 from science teams worldwide, which is twice the usual number for instrument competitions and demonstrates the extraordinary interest in Mars by the science community.

The 2020 rover architecture is based on NASA’s hugely successful Mars Science Laboratory (MSL) Curiosity rover which safely touched down a one ton mass on Mars on Aug. 5, 2012 using the nail-biting and never before used skycrane rocket assisted descent system.

The seven instruments will conduct unprecedented science and technology investigations on the Red Planet that’s aimed for the first time at simultaneously advancing both NASA’s unmanned robotic exploration searching for extraterrestrial life and plans for human missions to Mars in the 2030’s.

Planning for NASA's 2020 Mars rover envisions a basic structure that capitalizes on the design and engineering work done for the NASA rover Curiosity, which landed on Mars in 2012, but with new science instruments selected through competition for accomplishing different science objectives. Image Credit: NASA/JPL-Caltech — Planning for NASA’s 2020 Mars rover envisions a basic structure that capitalizes on the design and engineering work done for the NASA rover Curiosity, which landed on Mars in 2012, but with new science instruments selected through competition for accomplishing different science objectives. Image Credit: NASA/JPL-Caltech

The instruments will have the capability to detect low levels of organic molecules that are essential precursors to life.

A technology demonstration experiment will use Mars natural resources to generate oxygen from atmospheric carbon dioxide that can be used as rocket fuel or for human explorers. This will save enormous costs by enabling astronauts to ‘live off the land’ rather than having to bring everything needed for survival from Earth.

NASA said that the development cost for the chosen instruments is approximately $130 million out of a total cost of $1.9 Billion.

This overall cost is less than Curiosity’s approximate $2.4 Billion cost since the team is rebuilding the rover and landing architecture – sort of an MSL 2 so to speak – developed for Curiosity and also using several left over MSL flight spares.

Mars 2020 builds on the architecture developed for Curiosity.
Curiosity’s panoramic view departing Mount Remarkable and ‘The Kimberley Waypoint’ where rover conducted 3rd drilling campaign inside Gale Crater on Mars. The navcam raw images were taken on Sol 630, May 15, 2014, stitched and colorized. Credit: NASA/JPL-Caltech/Ken Kremer – kenkremer.com/Marco Di Lorenzo

The Mars 2020 rover will also have a sample cacher with the ability to store core samples collected by the rover’s drill for later retrieval and return to Earth at an as yet unspecified time.

“The Mars 2020 rover, with these new advanced scientific instruments, including those from our international partners, holds the promise to unlock more mysteries of Mars’ past as revealed in the geological record,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington.

“This mission will further our search for life in the universe and also offer opportunities to advance new capabilities in exploration technology.”

NASA’s Mars 2020 rover will explore the Red Planet like never before. Credit: NASA

Here’s a list of the 7 selected science payload proposals. They are in some ways more advanced versions form Curiosity and in other ways completely new:

Mastcam-Z, an advanced camera system with panoramic and stereoscopic imaging capability with the ability to zoom. The instrument also will determine mineralogy of the Martian surface and assist with rover operations. The principal investigator is James Bell, Arizona State University in Phoenix.

SuperCam, an instrument that can provide imaging, chemical composition analysis, and mineralogy. The instrument will also be able to detect the presence of organic compounds in rocks and regolith from a distance. The principal investigator is Roger Wiens, Los Alamos National Laboratory, Los Alamos, New Mexico. This instrument also has a significant contribution from the Centre National d’Etudes Spatiales,Institut de Recherche en Astrophysique et Planetologie (CNES/IRAP) France.

Planetary Instrument for X-ray Lithochemistry (PIXL), an X-ray fluorescence spectrometer that will also contain an imager with high resolution to determine the fine scale elemental composition of Martian surface materials. PIXL will provide capabilities that permit more detailed detection and analysis of chemical elements than ever before. The principal investigator is Abigail Allwood, NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals (SHERLOC), a spectrometer that will provide fine-scale imaging and uses an ultraviolet (UV) laser to determine fine-scale mineralogy and detect organic compounds. SHERLOC will be the first UV Raman spectrometer to fly to the surface of Mars and will provide complementary measurements with other instruments in the payload. The principal investigator is Luther Beegle, JPL.

The Mars Oxygen ISRU Experiment (MOXIE), an exploration technology investigation that will produce oxygen from Martian atmospheric carbon dioxide. The principal investigator is Michael Hecht, Massachusetts Institute of Technology, Cambridge, Massachusetts.

Mars Environmental Dynamics Analyzer (MEDA), a set of sensors that will provide measurements of temperature, wind speed and direction, pressure, relative humidity and dust size and shape. The principal investigator is Jose Rodriguez-Manfredi, Centro de Astrobiologia, Instituto Nacional de Tecnica Aeroespacial, Spain.

The Radar Imager for Mars’ Subsurface Exploration (RIMFAX), a ground-penetrating radar that will provide centimeter-scale resolution of the geologic structure of the subsurface. The principal investigator is Svein-Erik Hamran, Forsvarets Forskning Institute, Norway.

So the instruments are more sophisticated, upgraded hardware versions as well as new instruments to conduct geological assessments of the rover’s landing site, determine the potential habitability of the environment, and directly search for signs of ancient Martian life, according to NASA.

Creating a Returnable Cache of Martian Samples is a major objective for NASA's Mars 2020 rover. This prototype show hardware to cache samples of cores drilled from Martian rocks for possible future return to Earth. The 2020 rover would be to collect and package a carefully selected set of up to 31 samples in a cache that could be returned to Earth by a later mission. The capabilities of laboratories on Earth for detailed examination of cores drilled from Martian rocks would far exceed the capabilities of any set of instruments that could feasibly be flown to Mars. The exact hardware design for the 2020 mission is yet to be determined. For scale, the diameter of the core sample shown in the image is 0.4 inch (1 centimeter). Credit: NASA/JPL-Caltech — Creating a Returnable Cache of Martian Samples is a major objective for NASA’s Mars 2020 rover. This prototype show hardware to cache samples of cores drilled from Martian rocks for possible future return to Earth. The 2020 rover would be to collect and package a carefully selected set of up to 31 samples in a cache that could be returned to Earth by a later mission. The capabilities of laboratories on Earth for detailed examination of cores drilled from Martian rocks would far exceed the capabilities of any set of instruments that could feasibly be flown to Mars. For scale, the diameter of the core sample shown in the image is 0.4 inch (1 centimeter). Credit: NASA/JPL-Caltech

“Today we take another important step on our journey to Mars,” said NASA Administrator Charles Bolden.

“While getting to and landing on Mars is hard, Curiosity was an iconic example of how our robotic scientific explorers are paving the way for humans to pioneer Mars and beyond. Mars exploration will be this generation’s legacy, and the Mars 2020 rover will be another critical step on humans’ journey to the Red Planet.”

Ken Kremer