Two craft probe beneath these bodies surfaces
Feb 27th 2020
THIS WEEK has seen the publication of results collected by probes to two heavenly bodies: Change 4, a Chinese mission to the Moon, and InSight, an American mission to Mars. Change 4 landed in January 2019; InSight arrived the previous November. The Chinese team, bowing to the realities of scientific publishing, have presented their results in Science Advances, an American journal. The Americans, however, have chosen Nature Geoscience, a British journal owned by German publishers.
Change 4 is Chinas second successful lunar lander, and the first from any country to touch down intact on the Moons far sidethe part never visible from Earth. Its purpose, other than demonstrating Chinas technological prowess, is to investigate the geology of Von Krmn crater in the Moons southern hemisphere. To that end it is fitted with a ground-penetrating radar which can peer many metres down.
This radar shows three distinct layers of rock, the top two each 12 metres thick and the lowest 16 metres thick. Below that, the signal is too fuzzy to see what is going on. The upper layer is composed of regolithcrushed rock that is the product of zillions of small meteorite impacts over the course of several billion years, and which covers most of the Moons surface. The other two, distinguishable by the coarseness of the grains within them, are probably discrete ejecta from separate nearby impacts early in the Moons history that were subsequently covered by the regolith.
InSight (pictured above as an artists impression) is intended to probe deeper than this. It is fitted with instruments designed to measure heat flow from Marss interior, any wobble in the planets axis of rotation (which would probably be caused by an iron core) and Marsquakes. The heat-flow instrument has so far been a washout. The mole, a device intended to dig into Marss surface, pulling this instrument with it, has refused to co-operateto the point where the projects directors are about to take the time-honoured step of hitting it with a hammer (or, rather, with the scoop on the probes robot arm) to persuade it to stay in the hole that it is supposed to be excavating. And the wobble detector, though working correctly, has insufficient data to report. So the release this week is mainly about the quakes.
InSights seismograph recorded 174 quakes between the crafts landing and the end of September 2019. The strongest were between magnitudes three and fourjust powerful enough, had they happened on Earth, for a human being to notice them. Quakes are a valuable source of information about a planets interior. A network of seismographs, as exists on Earth, allows their points of origin to be triangulated, their speed measured and their reflections from subsurface rock layers observed. From all this can be deduced those layers composition and depth. With but a single instrument, such deductions are trickier. InSights masters do, though, think that two of the quakes originated in Cerberus Fossae, a set of faults 1,600km from the landing site that are suspected of still being seismically active.
This article appeared in the Science and technology section of the print edition under the headline "Beneath the surface"
Read the rest here:
The exploration of the Moon and Mars continues apace - The Economist
- Lilah Brown's Planets, Part II (or, Season II preview) - November 8th, 2009 [November 8th, 2009]
- Snow White needs a bailout - November 8th, 2009 [November 8th, 2009]
- To the moon - November 8th, 2009 [November 8th, 2009]
- S/1 90482 (2005) needs your help - November 8th, 2009 [November 8th, 2009]
- We'll always have Regulus - November 8th, 2009 [November 8th, 2009]
- Orcus Porcus - November 8th, 2009 [November 8th, 2009]
- Kant's Crowded Universe - November 8th, 2009 [November 8th, 2009]
- Look up! - November 8th, 2009 [November 8th, 2009]
- Baby Pictures - November 8th, 2009 [November 8th, 2009]
- Encore: Yelping at Saints - November 8th, 2009 [November 8th, 2009]
- Godspeed - November 8th, 2009 [November 8th, 2009]
- Heavens above! - November 8th, 2009 [November 8th, 2009]
- Homeward bound - November 8th, 2009 [November 8th, 2009]
- Sony Pictures and the end of the world - November 8th, 2009 [November 8th, 2009]
- Thank you from the future - November 8th, 2009 [November 8th, 2009]
- Lunar dreams - November 8th, 2009 [November 8th, 2009]
- The first of the Pluto books! - November 8th, 2009 [November 8th, 2009]
- Don't try to blame it on Rio - November 8th, 2009 [November 8th, 2009]
- Rio roundup - November 8th, 2009 [November 8th, 2009]
- The long road to a Titan storm - November 8th, 2009 [November 8th, 2009]
- Planetary Placemats - November 8th, 2009 [November 8th, 2009]
- Fog! Titan! Titan Fog! (and a peer review experiment) - November 8th, 2009 [November 8th, 2009]
- Millard Canyon Memories - November 8th, 2009 [November 8th, 2009]
- The problem with science - November 8th, 2009 [November 8th, 2009]
- P.S. on the problem with science - November 8th, 2009 [November 8th, 2009]
- How Big is 10 TB? - November 8th, 2009 [November 8th, 2009]
- Showing You Your Servers - November 8th, 2009 [November 8th, 2009]
- Pick Your Partnership: Referral Partners, Resellers and Affiliates - November 8th, 2009 [November 8th, 2009]
- Server Form Factors: Towers v. Rack-Mounts - November 8th, 2009 [November 8th, 2009]
- Lights-Out in the Data Centers - November 8th, 2009 [November 8th, 2009]
- Disruptive Technologies: Virtualization and The Cloud - November 8th, 2009 [November 8th, 2009]
- Know Thy Backups – Part I - November 8th, 2009 [November 8th, 2009]
- Know Thy Backups – Part II - November 8th, 2009 [November 8th, 2009]
- Boo Bash 2009 – Desktop Costume Included! - November 8th, 2009 [November 8th, 2009]
- Why No One Will Talk About “Cloud Computing” in 10 Years - November 8th, 2009 [November 8th, 2009]
- The end of the fall - December 13th, 2009 [December 13th, 2009]
- We Love ‘Server Huggers’ - December 13th, 2009 [December 13th, 2009]
- All About the Cloud: An Interview with Dell’s Cloud Evangelist - December 13th, 2009 [December 13th, 2009]
- Happy Solstice - December 21st, 2009 [December 21st, 2009]
- A ghost of Christmas past - December 31st, 2009 [December 31st, 2009]
- Learning from a Blender - January 5th, 2010 [January 5th, 2010]
- Changing my world - January 6th, 2010 [January 6th, 2010]
- A Server. From Scratch. - January 7th, 2010 [January 7th, 2010]
- The Planet Sand Castle: Upgrade Your Sandbox - January 12th, 2010 [January 12th, 2010]
- Hosting for Haiti - January 20th, 2010 [January 20th, 2010]
- Redefining Value - January 26th, 2010 [January 26th, 2010]
- My Experience as a Newbie at The Planet - January 28th, 2010 [January 28th, 2010]
- Confessions of Another New Planeteer - February 1st, 2010 [February 1st, 2010]
- How I Learned to Stop Worrying and Love Permissions - February 11th, 2010 [February 11th, 2010]
- Where at The Planet is Rachel? - February 15th, 2010 [February 15th, 2010]
- The Planet Storage Cloud: FYI - February 19th, 2010 [February 19th, 2010]
- Meet us in March - February 25th, 2010 [February 25th, 2010]
- The Planet in “The Channel” - March 2nd, 2010 [March 2nd, 2010]
- The Planet Server Challenge - March 13th, 2010 [March 13th, 2010]
- The Definitive Guide to Finding The Planet at SXSW - March 13th, 2010 [March 13th, 2010]
- The SXSW Iron Geek Champion! - March 15th, 2010 [March 15th, 2010]
- Drinking from the Fire Hose - March 16th, 2010 [March 16th, 2010]
- The Fastest Hands at SXSW - March 17th, 2010 [March 17th, 2010]
- System.out.println(“Hello World!”); - March 22nd, 2010 [March 22nd, 2010]
- Westmere – Get it Here - March 23rd, 2010 [March 23rd, 2010]
- Orbit on Your iPhone: A Sign of Things to Come - March 24th, 2010 [March 24th, 2010]
- #ShowMeMyServer 2.0 - March 25th, 2010 [March 25th, 2010]
- Get to Know Your Visitors - March 30th, 2010 [March 30th, 2010]
- The Next Big Thing in Hosting: The Hostatulator - April 1st, 2010 [April 1st, 2010]
- Storage Cloud and the City - April 4th, 2010 [April 4th, 2010]
- American Heart – Why I Walk - April 7th, 2010 [April 7th, 2010]
- The Cake Shouldn’t Be a Lie - April 8th, 2010 [April 8th, 2010]
- April Showers Bring May Flowers - April 9th, 2010 [April 9th, 2010]
- First at The Planet: Nehalem EX 4-Socket Servers - April 15th, 2010 [April 15th, 2010]
- Intel Guest Blog: Xeon 5600 - April 16th, 2010 [April 16th, 2010]
- Inside the Office: A Birthday Surprise - April 18th, 2010 [April 18th, 2010]
- The Planet @ Cloud Expo East - April 19th, 2010 [April 19th, 2010]
- The Planet @ ad:tech SF - April 22nd, 2010 [April 22nd, 2010]
- ad:tech Server Challenge - April 22nd, 2010 [April 22nd, 2010]
- ad:tech Panel: Developing Communities Online - April 23rd, 2010 [April 23rd, 2010]
- The Planet @ Interop Las Vegas - April 27th, 2010 [April 27th, 2010]
- Overflowing With Value: 10TB is Back! - April 28th, 2010 [April 28th, 2010]
- The Cloud is NOT the Revolution - April 29th, 2010 [April 29th, 2010]
- The Importance of Orbit 2.0 - May 5th, 2010 [May 5th, 2010]
- The Planet @ Web 2.0 Expo - May 6th, 2010 [May 6th, 2010]