Month: April 2019

There were people sitting on chairs on a stage. They were all introduced, including Dr. Shep Doeleman, the Director of the Event Horizon Telescope (EHT) project. There was applause, and then there was silence as everyone in the room sat up to listen closely and to see the picture they all hoped to see. The presentation was succinct, but everyone whether in the room or watching remotely from their offices or homes was waiting for the anticipated announcement. These included scientists, post-docs, students, managers, politician, reporters, and other interested people watching and listening. These other interested people were called the “black-hole enthusiasts”. The work was described, including the development of a Very Long Baseline Interferometer the size of the earth with multiple sites at locations around the globe. Not all of the sites were able to view the target location at the same time, but this supported obtaining good data since as the world turned other sites/telescopes were able to view the target location in space. High levels of collaborative processes were required for the EHT team to be successful.

The target was in galaxy M87, also known as Virgo-Alpha. It is the largest galaxy in the Virgo cluster. At the heart of the galaxy is a super-massive black hole. The international team was seeking to “image”, to create a picture, of the event horizon of the black hole in M87.

The room was quiet. Dr. Doeleman turned toward the screen and pressed the button on his control. For a moment there was total silence followed by the soft clicks of cameras in the room. Then applause. It did not carry on for wave after wave, but it was solid and positive and excited. The applause stopped as everyone in the room leaned forward to see the image. Everyone quieted down as if there were a sound to be heard. Every ear strained; every eye refused to blink.

The image on the screen clearly showed the edge of the event horizon inside of which not even light can escape. Dr. Doeleman stressed that it was the work of numerous nations, their agencies, and their early-career and senior scientists that made possible the development of the pictures. The pictures were created from more than 5-petabytes of information. It was the hard work of all these people that enabled the image seen today to be extracted from the mass of data.

Enthusiasts at home leaned closer to their computer screen and rose on the edge of their chairs. The room was full of virtual attendees who wanted to be part of this announcement of what is truly scientific history.

The picture showed (“north” being up in the picture) a glowing mass of light, the swirl of particles around the heart of galaxy M87 before they cascade across the event horizon into the darkness. The colors in the maelstrom indicated the speed of photon emissions from the accretion flow toward the event horizon. There was a distinct rise in color as the relative speed of the light flowing towards the observing telescopes in 1-mm wavelength increased on the south edge of the ring. And there in the center, the darkness of no light escaping, the back hole. And between the two the crisp edge of the event horizon.

The first-of-its-kind image and the science and math behind it and the cooperation behind it all, leads us to a transformation of our understanding of black holes.

Congratulations to the entire team and all those who supported and continue to support them.

The image of the black hole is based on the image provided by the NSF-EHT. The map of Virgo is based on a map provided by IAU and Sky and Telescope.

The announcement and press briefing can be viewed at https://www.nsf.gov/news/special_reports/blackholes/ .

Tap. Tap. Tap.

Then – no further.

One of the dedicated science instruments on the Mars InSight lander has had to pause during its deployment. The instrument is officially known as the Heat Flow and Physical Properties Probe, which according to the Launch Press Kit is abbreviated HP3 (pronounced “H-P cubed”). Its mission is to take the temperature of Mars. It will determine the amount of heat that is escaping from the interior of the planet. Knowing this heat flow will help us better understand the evolution of the Martian interior – and the rate at which Mar’s internal core energy is diminishing.

The instrument includes a probe that is being hammered into the Martian soil to a depth between ten and sixteen feet (3 – 5 meters). But the probe, which is called the “Mole” by NASA, has met significant resistance at a much shallower depth. NASA is trying to determine if the resistance is coming from a rock or a gravel layer. Then they will need to decide how best to get beyond the obstacle. Can it be penetrated, or will another method be necessary?

As a gardener, or I should say as the shovel-man for a gardener, I know what it is to hit a resistive object while digging a hole. For me the resistance is often a stone of small to moderate size or perhaps a root of a nearby tree. Sometimes I can remove the impediment, but sometimes I must shift the location of the hole. Removing the impediment is not an option on Mars. There is no gardener on Mars that can kneel and sweep out the rubble with their gloved hand. *

The Mole is about 16 inches long and approximately an inch in circumference. The exterior of the Mole is aluminum. It is attached to a flexible tether that carries information to the instrument package that is attached to the deck of the lander. The hammer that provides the driving force is built into the Mole. There is no outside hammer at the surface level to drive the Mole into the soil. This means that there is no device, like the claw on the back of a hammer, that can extract the Mole so it can be placed in a different location.

Going back to my gardening efforts, I have often driven spikes for mats or pegs for garden borders into the ground. I have also driven steel rods to a depth or 18 to 24 inches to support a structure or a wall. In these cases, if I hit a rock or a root that I cannot penetrate I may be able to slightly reorient the item and try to slide past the obstacle. But that may not to be an option for the Mole on Mars. For clarity, I will have to ask NASA.

The Mole’s internal hammer was designed to enable the tip of the Mole to penetrate objects up to a certain hardness. This can be understood from the description of the operation in the mission Launch Press Kit which describes the process. The information in these documents states that it is expected that the hammer will be dropped between 5,000 and 20,000 times to penetrate the soil to its planned depth. The number of hammer blows required depends on the density and hardness of the soil matrix.

Currently the Mole has met an object of significant hardness. The hammer not only has to overcome the hardness of the material it has to penetrate, but it also has to overcome the friction of the sides of the Mole as it is driven through the obstacle plus the added friction of the flexible tether as it is dragged down the Mole’s hole.

NASA will determine the best course of action to allow the Mole to penetrate beyond its current depth. On March 21, the NASA Mission page stated that many ideas are being considered to free the Mole from the obstacle, and that the ideas will require “at least several more weeks of careful analysis.”

Stay tuned. Perhaps we will be able to slide past the obstacle and reach the appropriate depth.

Information for this article is taken form the NASA Mars InSight Launch Press Kit. The documents may be found at https://www.jpl.nasa.gov/news/press_kits/insight/ .

Picture based on NASA map in Launch Press Kit.

*I always wear gloves because there can be glass from an old bottle or a rusted nail dropped during construction.