Sunday, August 30, 2020

Asteroid Threats

 Update 9-26-2020:

Asteroid 2020 SW was discovered 9-18-2020,  and made its closest approach on 9-24-2020.  The warning time was thus 6 days.  It was estimated to be 5-10 m in size.  Closest approach distance was 22,000 km. 

Using the somewhat-arbitrary density of 2.5 g/cc = 2500 kg/cu.m,  that corresponds to a mass between 49.7 and 398 metric tons.  This definitely falls in the city-buster range for speeds between 10 and 20 km/s,  if it were to impact the surface,  or explode close to it. 

Given 6 days notice,  it might have been possible to evacuate a threatened city.  This one could have been a "success" story,  rare among those listed in the article. 

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Original article:

In 2009 I attended a meeting held in Spain about defending Earth from threatening asteroid impacts.  At that time,  we had been able to locate most of the large (extinction-event) objects,  we were starting efforts to locate the smaller “city-buster” objects,  and we had some ideas about how to deal with them.  

I'm sorry to report that not much has changed since then.  We are now beginning to find some of the smaller "city-busters",  but that's about it.

Recent public news accounts:

Asteroid 2020QG passed ~1830 miles from Earth on Sunday 8-23-20.  It was not seen until some 6 hours after it passed.  This object was 10-20 feet (3-6 m) in diameter (for those unfamiliar with metric,  a meter is about 10% longer than a yard). Its speed past the Earth was ~27,600 mph.  An on-line animation in Wikipedia shows ~12.3 km/s at ~9300 km center-to-center.

Asteroid 2018VP1 is predicted to pass Earth Monday 11-2-20 (the day before election day in the US),  give or take ~2 days,  depending upon whose estimate you believe.  It is said to be 6.5 feet in size. It is listed in Wikipedia as 2-4 m size,  with an animation that shows a fairly-slow 9.7 km/s pass,  about 419,000 km center-to-center away (not far outside the moon's orbit). 

A somewhat-recent event,  only a few years ago:

The Chelyabinsk object was about 20 m dia,  with 19.16 km/s velocity,  estimated at 12,000-13,000 metric tons.  It exploded in the atmosphere,  with a yield estimated at 400-500 KT-equivalent to a nuclear weapon (where 1 KT = 4.184 GJ). This thing fell 2-15-2013,  and was completely undetected before its entry. It injured around 1000 people,  and blew out most of the windows in that city.

Here are the data as listed in Wikipedia,  for the previous 2 years,  plus this one so far.  To this I added the Chelyabinsk object.  It would take more than a day to evacuate a city that was threatened by such an event,  which is why the measure of warning time is important.   That list is in Figure 1.

So,  note the warning times color-coded in the list.  Only the single green one might have afforded sufficient time to evacuate.  Note also that a center to center distance under 6.37 thousands of km is a direct impact,  because that figure is the radius of the Earth.


Figure 1 – List of Small Asteroids Recently

Conclusion:  our track record seeing the small ones before they pass is NOT good at all,  whether or not we include the Chelyabinsk object!

What’s still coming that we know of:

Here are the predictions for some selected future encounters,  per Wikipedia,  as Figure 2.  To this I added the recently-reported "election day" object. The notation "LD" refers to lunar distance.  If "yes",  the predicted encounter leads to a pass within the orbit of our moon.  Bear in mind that both measurement inaccuracies and any sort of disturbance can throw these close-pass center-to-center distances off. 


Figure 2 -- Known Future Threats

The point here is that we already know of some larger objects that will pass uncomfortably close in the coming years.  Smaller objects are more numerous,  and mostly as-yet undetected.  That means there are a lot of “city busters” out there,  some of which we can expect to hit us.  This threat is quite real!

Figuring the explosive yield range of air bursts and impacts:

Chelyabinsk object:  20 m dia sphere has 4189 cu.m volume.  Using middle-of-the-road mass 12,500 tons = 12.5 E6 kg,  density is mass/volume = 2984 kg/cu.m.  Fresh water is 1000 kg/cu.m,  so the specific gravity is about 2.98.  How consolidated that object was,  is unknown.  But it's the best data available to me.   Most minerals are in this range of density.

A "typical" small asteroid is 2-6 m in size.  Treating that as the diameter of a sphere,  "typical" volumes are 4.19-113 cu.m.  Using the Chelyabinsk object estimate of 2980 kg/cu.m density,  the "typical" masses are 12,500 kg = 12.5 metric tons,  up to 337,000 kg = 337 metric tons. 

The actual astronomers have better data to use in such calculations than I have,  but their methods and formulas,  and mine,  are the same.  This stuff is just not as certain as it often appears to the public.

About the lowest velocity ever seen is near 10 km/s,  and about the highest velocity to be expected is nearer 20 km/s,  at least as a good guess.  Kinetic energy is 0.5 mass x velocity squared,  where for mass in kg and velocity in m/s,  you get energy in Joules:  kg m^2/s^2 = N-m = J.  Every 4.184 billion Joules is a kiloton (KT) equivalent to a nuclear weapon.

I used these data to estimate the results in Figure 3.


Figure 4 – Kinetic Energy As Equivalent Nuclear Weapon Yield

These figures say that these 2-6 m size "small asteroid" objects will have energies comparable to nuclear warheads in the 150 KT to 16 MT range.  They are very definitely "big-city-busters"! 

For comparison,  the Hiroshima and Nagasaki bombs were about 15 and 20 KT in yield.  Many of our military warheads are now in the 200 KT range.  The giant "Tsar Bomb" test,  of October 1961 in the Russian arctic,  was around 66 MT,  the largest nuclear explosion ever seen.

Not only are these real city-buster threats,  we also have a poor track record of seeing them until it is too late! That is precisely because they are small,  dark,  and often approach from a more sunward direction,  where our ground-based telescopes are blind.

There are differences with nuclear weapon effects:

The kinetic energy of these things is not the whole story,  unlike nuclear weapons.  There are also the tremendous interplanetary speeds,  and the downward angle of the entry trajectory. 

Unlike a nuclear weapon,  the fireball associated with an air burst is still traveling along the trajectory at great speed for a while.  If during that interval,  it gets close to (or impacts) the surface,  it will incinerate everything in the vicinity.

Downward angle plays a strong role,  too.  The Chelyabinsk object struck at a very shallow angle across the sky,  so that its air burst happended dozens of miles up in the air. Had this been steeper downward,  the burst would have been much closer to the city,  utterly destroying it,  and killing its people. 

A little steeper still,  and the object might have struck the surface without bursting in the air.  That just releases even more blast and heat right at the impact point. 

What we need:

(1) We need to be able to detect these things,  in time to actually do something about them! 

(2) We need to obtain real ground-truth data directly from them,  so that we can figure out exactly what to do,  given the chance. 

(3) We need to implement those means of doing something,  which includes both the means to get there fast enough,  and the actual means to deflect or destroy them.

Detection:

The B612 Foundation at one time proposed an asteroid-defense satellite to be placed in an orbit nearer that of Venus than Earth, so that it could see threats approaching Earth from sunward,  by being even more sunward,  but looking outward from the sun. 

The sensor of this proposed satellite was not based on visible light or radar,  but infrared.  These objects are brighter and easier to see in the infrared than in visible light (or radar),  although they are still dim.

We still need that satellite,  and preferably 2 or 3 of them at any one time!  We do not have any of them!  What we do have (mostly telescopes based on Earth),  is having great difficulty seeing things that are only 1-100 m in size. 

That is because (1) these telescopes are not located sunward of Earth looking outward at dark,  cold deep space,  and (2) they does not use infrared (asteroids,  being somewhat near the sun,  are simply warmer than the cold of deep space).

Knowing how to deflect or destroy:

There seem to be three general types of these small objects. (1) By far the most numerous are those that seem to be made of a mix of carbonaceous and stony particles,  not very consolidated (and often with significant void spaces internally),  and actually rather weak structurally. 

These are essentially flying sand-and-gravel-and-boulder piles, which would fly completely apart if you actually pushed against one. These are the ones that tend to explode up in the atmosphere,  from the suddenly-crushing drag forces of encountering air while moving at interplanetary speeds. 

The small solid particles of post-explosion debris,  if larger than about a quarter inch diameter,  actually do not burn up entirely,  and hit the ground at modest speeds.

(2) There are a few asteroids that are really more-or-less solid rocks,  made of a mix of different minerals,  and even some metal content.  These tend to hang together fairly well,  and would likely not fly apart out in space,  if you pushed against one,  at least fairly gently. How internally fractured they really are,  is an open question.

These bodies tend to make it to the Earth's surface,  if larger than about a quarter inch.  Not being debris of an atmospheric explosion,  they are moving very much faster when they hit,  causing their own explosions and craters.

(3) There are a very,  very few that are actually solid chunks of metal,  mostly iron.  If larger than about a quarter inch,  they make it through the atmosphere to strike at very high velocities as one solid object.

This produces really big explosions and craters.  Meteor Crater in Arizona was created about 50,000 years ago by one of these,  just about the size of the objects we are interested in detecting and deflecting-or-destroying.

Some of these we could push against (in some way) and deflect into a miss,  if we could get there in time to do it.  But not the most-numerous unconsolidated bodies.  Those will fly apart if pushed,  creating a storm of debris. 

If that disruption of the threatening object happens close to the Earth,  then you just turned a damaging bullet strike into an even more damaging shotgun blast!  That strategy is viable only if you can do it far enough from the Earth that most of the debris storm you have created will miss.  See Figure 4.


Figure 4 – Bullet Strike vs Shotgun Blast,  with Timing

Deflection / destruction techniques:

Space is a vacuum.  There is nothing out there to propagate a blast wave.  Nuclear explosions create great heat as radiant energy,  but no blast out there.  You won't have time to drill (and we don't know how to drill into these things anyway) to emplace a nuclear bomb inside one of these bodies.

What you do is detonate your nuclear device alongside the threat.  The immense amount of radiant heat will vaporize and spall-off significant mass from it,  hopefully without completely disrupting it.  The resulting momentum "kick" in the opposite direction will subtly alter the body's trajectory.  Do this "right",  and "soon enough",  and you can cause it to miss.

The same sort of thing can be done with impactors instead of nuclear weapons.  You hit the thing from the right direction,  and "soon enough",  and the impact creates the spall-off,  just on a smaller scale than a nuclear explosion.  The momentum reaction changes the body's course slightly,  provided that it is not disrupted.  See Figure 5. 

 

Figure 5 – How Spallation Creates a Force

The gentlest technique is the so-called "gravity tractor".  This takes the longest time to have effect,  so you must know (and go) years in advance of the impact threat to Earth. You send a spacecraft to rendezvous,  and hover,  alongside the body. 

Its propulsion prevents its falling onto the body.  But the tiny force of gravity between spacecraft and body forces the body to "follow the spacecraft".  This is a very tiny effect,  but it is real.  See Figure 6.


Figure 6 -- Gravity Tractor

To summarize – see Figure 7.


Figure 7 -- Actions We Can Take,  with Timing

What to do about this:

Now look carefully at the indicated timing required in Figure 7,  and compare that to the track record seeing these threats in advance of their approach in Figure 1.  It is NOT GOOD!  We should be working on this,  but are mostly not.  THAT is why we need the detection satellites.

Getting there soon enough to do any good:

For an Earth-crossing asteroid,  there is a short window of time to get there from here,  and a very demanding propulsion requirement to do the mission,  even if a one-way trip with an unmanned spacecraft.  The perihelion velocity of the asteroid is substantially higher than the Earth in its orbit about the sun,  by at least 2-3 km/s. 

What you have to do to get there is wait until the Earth is in the "right place" in its orbit about the sun,  relative to where the asteroid is. You cannot go "just any time you want",  like we can to the moon.  Then you escape from the Earth,  and wait in an Earth-like orbit about the sun for the asteroid to catch up with you.  Then you burn a second time to catch up with the faster asteroid. 

The cost of all this (14+ km/s) is more than a direct one-way shot to Mars at optimum orbital positions (about 12 km/s).  See Figure 8.


Figure 8 – Traveling to an Earth-Crossing Asteroid

If you send astronauts,  then they must have a way home.  Before it is too late (days to weeks),  they must depart the asteroid into an Earth-like orbit,  waiting for the Earth to catch up with them.  Then you might do a free entry,  or you might do a propulsive deceleration into Earth orbit,  to bring them home. 

At the very least this is 17 km/s velocity change required. Maybe over 20 km/s. At present,  we have no rocket vehicles capable of flying this fast.  We will need nuclear propulsion,  or else very huge chemical rockets pushing very small probes and space capsules.

Why humans need to go,  sooner or later:

A robot can only deal with what its programmers anticipated.  It just cannot adapt to the unexpected or the unforeseen,  without direct human intervention.  That is simply just one of the truths of our time. 

Across the distances needed,  it is just not feasible to remotely-operate a probe,  in anything resembling a timely fashion.  Light just does not cross those distances that fast.  Another truth of our time. 

What that really means is this:  sooner or later in the process,  humans simply must go to these asteroids to investigate their real "ground truth" properties. There is just no other way at this time in history to find out "what is" versus "what is not". 

This isn't like going to the moon,  which was a mission about a week,  to at most two weeks,  long.  We are talking about weeks to months in space for the Earth-grazing asteroids.  For the non-Earth-grazing asteroids,  and for most comets,  we are really talking about years in space.  And we just don't know yet how to do that,  without killing our crews.

Bottom line:  we need more capable rockets,  and we need a vehicle for crews that provides artificial gravity and radiation protection. These voyages could range from days to years in duration,  and a small space capsule is only "good" psychologically for a couple of weeks.  These living spaces must be large

Conclusions:

There is no better reason for both unmanned,  and manned,  space program efforts than protecting the Earth against asteroid impacts.  The massive extinction event 66 million years ago that extinguished the dinosaurs in favor of the mammals,  is just one example of what damage a 6-10 km size object can do. 

This is not a zero-sum game (despite what politicians insist);  this is something that needs to be ongoing,  at whatever level we think we can afford,  in any given year.  Spend more when you think you can afford more,  simple as that.  But NEVER zero!  Some outcomes are just not tolerable,  no matter how unlikely! 

I recommend the following things be done:

(1) Deploy a constellation of at least 3 asteroid-detection satellites,  using infrared detection devices supplemented by visible and radar,  in orbits about the sun approximately at the orbit of Venus. 

This is just not that expensive a thing to do,  and it will identify the vast bulk of the small (2-6 m) threats to the Earth.  Such would make evacuation of a threatened city possible for the first time.

(2) Develop a means to send unmanned probes,  followed by manned missions,  to several of the Earth-crossing asteroids,  to find out real "ground truth" about their characteristics.  The manned voyages will probably require enhanced propulsion,  possibly nuclear.  Crewed vehicles will be quite large.

The place to test nuclear propulsion safely is on the moon,  where there are no neighbors to annoy,  and where there is no air and water to pollute.  There is no better reason than this, for a return to the moon!  There are other reasons to go back to the moon,  but none are better than for helping to provide protection of the Earth against asteroid threats.

(3) Develop the rockets and the spacecraft needed to send humans to the Earth-crossing asteroids as soon as possible.  This requires both propulsion upgrades,  and it requires built-in protection against space radiation and microgravity disease.  (If you can go there,  you can go to Mars,  or pretty much anywhere else in the inner solar system,  including out to the main asteroid belt.)

What that really means is artificial spin gravity,  and about a meter or more of low molecular weight insulation materials to double as radiation shielding. And plenty of living space for long missions.

These were also my conclusions in 2009 at that meeting.  They have NOT changed since! 

If your elected and appointed officials are not addressing these issues,  you may safely conclude that they are lying to you,  whether by omission or commission.  In any event,  they are not protecting the public safety,  which is their sworn duty.  And that deserves your attention at election times.

Related articles:

4-21-09  On Asteroid Defense and a Good Reason for Having National Space Programs

7-22-09  On the Future of the US Manned Space Program

9-6-09   Space Program Public Support

10-31-09 The Future of NASA Manned Space

3-10-10  About Old "Project Orion" -- the Nuclear Explosion Drive

4-17-10  Space Recommendations

1-21-11  Fundamental Design Criteria for Alternative Space Suit Approaches

8-2-11  What Should the Government's Manned Space Exploration Strategy Be?

5-2-12  Space Travel Radiation Risks

12-31-12  On Long-Term Sustainable Interplanetary Travel

1-5-13  Using Nuclear Rockets Safely for Manned Space Travel

2-15-13  On the Two Dangers From Space Friday 2-15-13

10-2-13  Budget Moon Missions

11-17-13  Rocks From Space

11-17-14  Space Suit and Habitat Atmospheres

1-17-15  Stagnation in Space

4-11-15  Radiation Risks for Mars Trip

1-15-16  Astronaut Facing Drowning Points Out Need for Better Space Suit

2-15-16  Suits and Atmospheres for Space

3-3-16   Effects of Microgravity Demand Artificial Gravity

3-16-18  Suit and Habitat Atmospheres 2018

10-5-18  Space Radiation Risks:  GCR vs SFE

7-14-19  Just Mooning Around


Tuesday, August 25, 2020

Voting Safely

We have a national election coming up,  during a raging pandemic yet to be controlled.  Gatherings are rightly to be discouraged,  making vote-by-mail an attractive alternative.  That does raise issues of higher ballot disqualification rates,  and of much longer times needed to count them.  It also puts a huge burden on the post office to move those ballots in a timely fashion. 

Unfortunately,  this vote-by-mail option has been needlessly politicized,  and the post office's capacity to support such has been sabotaged by the political appointee running it!  Thus we need to be able to gather and vote in person,  and safely.  However,  there really is a way to do that

Voters must be wearing masks and disposable gloves,  and each voter needs to carry his own pencil.   The masks and gloves must be mandatory for entry inside the polling place.  Period.  This is based on science,  and on centuries of experience.  The pencil is to move the dials on the voting machine,  instead of just your gloved finger.  The idea is that 2 layers of protection working together are way better than just 1 layer.

Poll workers are going to need face shields.  They will need lots of disposable gloves to get through the day.  There is no way around that requirement,  driven by science.  Between the face shields and the masks on the voters,  they should be safe enough,  probably safer than while shopping at the grocery store.  That's the 2-layer effect working for them.

We will need more polling places open,  not fewer.  The lines need to be short,  and linestanders spaced out 6 feet apart.  Linestanders need to be wearing masks;  that plus the 6 foot rule are the 2-layer effectThis requirement needs to be enforced,  with serious penalties for noncompliance. Conspiracy theories about masks are just not tolerable.  But it cannot (and won't) work rightif you don't have enough polling places open!   So demand them!

The biggest change is a disinfectant wipedown of the keyboard of every voting machine after each voter is done (probably something we should have been doing even in normal circumstances,  but that's another discussion).  The voter himself can do this,  observed by poll workers

It takes a few minutes for the disinfectant to work,  so you will need more voting machines in each polling place,  to avoid the otherwise-inevitable slowdown.  The disinfectant wipedown by the voter is a third layer of protection.  It should help keep voters (and poll workers) safer still.

There,  I just told you how to run a vote-in-person election safely during this pandemic.  There is required protective equipment,  and the very-necessary enforcement of those requirementsThere is required extra polling place capacity to shorten lines.  Simple enough.  Now just get on with it!

And when some of you see your local elected officials fail to do these things, does that not suggest to you,  that you have the wrong local elected officials?

It certainly should!

You can vote.  So when you see perfidy like that,  go and do something about it!

Sunday, August 23, 2020

Protests vs Riots

In recent weeks,  there have been several columns published in the Waco,  Texas,  "Trib" newspaper about protesters and rioters.  These include the Gordon Robinson column awhile back,  and several more since,  including more than one,  in just one edition alone (Sunday 9 August)!  Surprisingly enough,  there are certain elements in all of these that I do in fact agree with,  despite the apparent drastic disagreements among columnists.

 There is very definitely a difference between a protestor and a rioter!  The “molotov cocktail” is just one of those differences.  That being said,  the heightened emotional tension during recent protests in the streets makes it very easy for a protester to be induced to stray across that line into rioting.  This is the long-known psychological reason behind the easy formation of lynch mobs.  It would be well to remember that!

Figure 1 shows what a protest looks like.  Figure 2 shows what a riot looks like.  Admittedly,  there’s not a lot of difference,  but you have to look closely,  and you have to really understand what you are seeing,  in order to respond appropriately.  One involves property damage,  the other does not. 


Figure 1 – What Protest Looks Like (Portland,  OR)

Figure 2 – What Rioting Looks Like (Portland,  OR)

The fact that a protest exists is trying to tell you that there is some problem needing to be solved!  Unless there is such a problem lacking solution,  there is NO need for a protest!  Simple as that!  We can always differ and argue about what those solutions might be,  but it is totally illogical to deny that there is a problem to be solved,  when folks are protesting. 

I’m not talking about small groups looking for publicity,  I’m talking about major,  mass protests.  Such things are as American as apple pie!  In point of fact,  mass protest is exactly how the American Revolution began!

The right thing to do is to understand what that unsolved problem is,  so that you can start developing proposed solutions to it. 

When solutions are being developed and debated,  the fundamental reason for protesting starts going away.  Thus the protests begin to abate,  and with them,  the risks of riots.  This is not perfect or immediate,  but it is simple enough to understand.  No matter who you are,  or what your politics might be.

All that being said,  there are political opportunists who prefer to make the problems worse,  not better.  These are the people you do NOT want to listen to!  They exist on both sides of the political spectrum.  The more extreme they are,  the more likely they are to do or say something to cause harm.  Barry Goldwater in 1964 was dead wrong:  extremism is bad,  no matter what!

Which makes you wonder just what fraction of the arsonists and looters seen in the current civil rights protests were actually far-right extremists masquerading as far-left extremists,  doing damage so as to discredit the generally-honest protestors?  That is a very good question!  I have seen many things debated about these protests,  but not that "false flag" issue.  Yet it seems to be a very real thing (read on).

Look again closely at Figure 2.  Many of the people breaking down the fence at the federal courthouse in Portland are white-skinned,  not black- or brown-skinned.  In fact the only skins that can be seen are white! 

Now look closely again at Figure 1Not all the skins that can be seen are white!  Those in the foreground are,  but look closer into the far field!  Many there are black or brown.  About what you might expect in a national population that is mostly white,  but with a significant black minority,  and a significant brown minority. 

Now think for yourself!  Could the difference in skin color count between Figure 1 and Figure 2 be right-wing extremists infiltrating the protests,  to give the more-or-less left-wing protesters a bad name,  by doing (or starting) the rioting,  arson,  and looting?  If you are honest with yourself,  you have to admit that this really could be true!  It’s right there in front of your eyes!

The other thing I haven't seen very much of, in the current public discussions,  is the issue of attitudes versus behaviors,  when it comes to racism.  You can regulate behaviors with laws,  but generally not attitudes,  which are passed-on in-private from parents to children.  (This is the real problem we have had since the Civil War!)  Yet it is attitudes that comprise the racism that previously enabled the centuries of overt owning-people slavery in our culture!   If you are honest with yourself,  you have seen this attitude thing just as I did,  as a child.  It never went away.

There is the overt institutional slavery of owning other human beings.  This was outlawed in America as a result of the Civil War.  But there are other kinds of slavery:  the repression we call "Jim Crow",  and also for-profit wage slaveryI remember seeing "Jim Crow" when I was a boy,  and I am glad to see it mostly (if not entirely) gone.  What remains of it,  is what is being protested:  it costs lives needlessly.  That is just unacceptable.

Wage slavery is something most all of you should be familiar with,  at one level or another.  Which is why I find it so surprising that so many of you have been on the side of "union-busting" for so many decades,  when collective bargaining has been the most effective (even if somewhat-flawed) tool we have had,  against wage slavery,  for well over a century-and-a-half now.  But that's another story.

 What's missing in the current protest scenario is distinguishing between protesters and rioters,  and responding appropriately.  Too many rioters are being given a "pass" to burn and destroy.  Too many honest protesters are being abused,  or kidnapped,  by unneeded federal troops,  or over-reacting police.  Too much of this has been politicized as "either my way or the highway",  and not enough attention paid to solving the very real problems these protests have identified.  And THAT is what I object to!

See Figure 3.  This is a US Navy veteran being gassed by police while not doing anythingnot even moving.  Seconds later,  he was beaten severely with batons,  all the while not resisting in the slightest!  We all saw the video footage of this on the TV news,  however it might have been labeled or explained.  This was utterly appalling!


Figure 3 – Portland Vet Being Gassed Right Before Being Beaten,  Totally Unresisting

THIS is a prime example of police over-reaction!  Why should it surprise anyone that protesters might respond to such violence,  with violence of their own?  That,  too,  is human nature!  Yet it all can be avoided,  if one simply understands the difference between protestors and rioters,  and responds appropriately.

Even so,  sometimes people respond in unexpected ways!  There was a protestor in Portland,  Oregon,  often termed “Naked Athena”,  who did not respond with violence to police violence in Portland.  Indeed,  she actually seems to have reduced the violence! 

Figure 4 is a photo of her in action.  “Naked Athena” was wearing only two articles of apparel:  a stocking cap and a covid mask,  which can be seen in other photos taken of her.  Considering the violence going on around her,  I find that she showed consummate bravery!  I don’t care what her politics were.  She deserves commendation for extraordinary bravery!

It depends upon the source you get this from,  as to whether her actions are deemed positive or negative.  Some sources refer to her as a “crazed Antifa terrorist”.  Which is utterly ridiculousHow is reducing violence “terrorism”?  It is not.

Be aware that your “favored sources” may be lying to you in that way!  I see an awful lot of such lies,  from both ends of the political spectrum!  So,  think for yourself!   


Figure 4 – “Naked Athena” Facing Down Federal Troops

We’ve seen enough violence on both sides of this!  It needs to stop!  So,  my message is simple: 

#1.  There is a difference between protestors and rioters.  You have to deal with them differently.  So,  learn the difference,  and just get on with that!

#2.  When there is protest,  there is something wrong that needs to be fixed.  So figure out what that is,  and just FIX IT!

My fellow citizens,  this stuff has to change!  Most of your current politicians clearly won’t act effectively.  Your most powerful tool is your vote!  Please use it!  Wisely!

That being said,  if you do not trust the post office to get your mail-in ballot where it needs to go on-time,  then vote in person!  There are ways to do that safely,  even in a pandemic!  (I will cover that in another post.)  

Update 1-8-2020:  In response to the comments to this article (below) about whether the far left or the far right might present the greater terrorist threat,  note that today some 13 far-right persons from two separate groups have been arrested and charged with planning to kidnap (and "try for treason" the governor of Michigan,  who happens to be a Democrat who took Covid-19 seriously,  and has imposed some quarantine measures to fight the spread of the disease.  

These people hated those quarantine measures,  among other things.  6 are facing federal charges,  and 7 are facing state charges.  The FBI broke this one.  They are radical right wingers,  charged with intending to commit a terroristic event. 

A right-wing Q-follower tried shoot up a pizzeria in NYC to "save the children from the pedophile ring operating in the basement",  per what the Q community believed;  when that pizzeria physically didn't even have a basement.  A right-winger hit and killed a leftist with his car in Charlottesville.  Several in the news media have noted the presence of outsiders,  not associated with the protestors,  committing or fomenting the violence associated with the civil rights protests.  Multiple black males,  all unarmed,  have recently died in police custody.  And now this:  right-wingers wanting to kidnap state officials they disapprove of,  and perhaps "try" them for treason.  

Looks to me like the FBI is quite correct in its recent assessment:  the worst domestic terrorist threat comes from the far right,  not the far left.  I don't like extremists of either stripe,  but the greater threat is so very clearly coming from the far right. 

Thursday, August 20, 2020

Underhood Check

Open up the hood,  and look for the engine oil dipstick,  the transmission fluid dipstick,  and the reservoirs for coolant overflow,  power steering fluid,  brake fluid,  and windshield washer fluid.  Also locate the engine oil filler cap.  If you have a manual transmission,  there won’t be a transmission fluid dipstick,  but there might (or might not) be a clutch fluid reservoir and some sort of associated small dipstick.  See Figure 1,  but bear in mind that not every car puts these things in the same places. 


Figure 1 – Orientation As To Where Things Are

Figure 1 shows under the hood of a 2005 Ford Focus.  To photo left is the front of the transverse-mounted engine where the belts are,  with the joint to the transmission more toward photo right.  The larger plastic tank on the left is the coolant overflow bottle,  and the smaller one near it the power steering fluid reservoir.  Also near these is a yellow arrow point to the oil filler cap.  The yellow ring-shaped thing is the handle of the oil level dipstick. 

At photo rear and right is another reservoir,  this one is the brake fluid reservoir.  There is another yellow arrow,  photo right and front,  pointing to a not-so-obvious ring-shaped thing.  That is the handle of the automatic transmission fluid level dipstick.

Right next to the trans fluid dipstick is a black plastic tubular object:  that is part of the air intake,  coming from the air filter out of the photo to the right.  Near it are two black plastic rectangular box-looking objects.  The nearer one is a cover over the top of the battery.  The farther one is the fuse box.

The windshield washer fluid bottle on this car is located to photo left,  at the rear.  These vary in location from vehicle to vehicle.  The majority of them are up front in the engine compartment somewhere.

You are most concerned with the fluid levels in the reservoirs and the two dipsticks.  Consult your owner’s manual to make sure you understand what each of those fluids is supposed to be.  Putting in the wrong one can ruin machinery,  which is very expensive indeed!  Use the right stuff.   

You should do this underhood check on a regular basis.  It could be monthly on a newer vehicle,  perhaps weekly on one of medium age.  Do most of this before every start on an old vehicle.

Checking the Engine Oil

Engine oil is characterized by its viscosity and its lubricity,  which are NOT the same thing!  Viscosity is the one or two-number index,  such as SAE 30 or SAE 5W-20.  The right viscosity grade to use is specified in the owner’s manual.  Smaller numbers indicate “thinner” (really,  less viscous) oils.  For the two-number grades,  the first is the viscosity rating at 0 F (for cold winter starts),  and the second is the viscosity rating at 200 F (for hot engine operation). 

The viscosity rating must be right for the moving parts (bearings of multiple types) to “float” on a film of oil.  Too little and they rub together and wear disastrously fast.  Too much and the oil cannot get to the moving parts fast enough,  so they rub together and wear disastrously fast.

Lubricity is the two-letter index such as S-M,  S-N,  or C-C.  The first letter indicates what type of engine (S is for spark ignition,  C is for compression ignition,  which is diesel).  The second letter should be at least as late in the alphabet as is specified in your owner’s manual.  The further into the alphabet,  the more lubricity this oil has. It protects the moving parts intended to float on a film of oil,  that are actually rubbing together dry when you first start the engine,  before the oil gets there to make the film.  Lubricity also protects those other parts which do not float on a film of oil while the engine is running (cylinder walls and piston rings,  valve train parts,  etc.). 

The viscosity and lubricity are given in an API “doughnut” symbol somewhere on the oil container,  for all oils that are actually tested and verified to meet those specifications.  If that API symbol is not on the container,  then that oil does not meet API specs,  and should not even be used in a lawnmower!  See Figure 2. Everything else on the container label is advertising hype. 


Figure 2 – Where the Trustable Information Is,  On An Oil Container

Figure 2 shows the back side of a typical oil container.  Because this one has a custom blend in it,  I marked out the viscosity,  to remind myself about it being such a blend.  However,  the API “doughnut” is what you should look for,  when buying oil.  This one is marked by the yellow arrow.  It contains the lubricity rating “API Service SN”,  and the viscosity rating “SAE 5W-30”.   The note just below it reminds the user that it meets or exceeds the earlier lubricity specs SM,  SL,  and SJ. 

What you buy should always meet or exceed the lubricity spec,  and should match the viscosity that the owner’s manual says to use.   The only exception would be an old,  worn engine,  which should be filled with one grade more-viscous oil:  such as 10W-40 instead of 5W-30.  For a two-number viscosity grade,  it is the second (hot engine) number you are more worried about,  with an old,  worn engine (so a 10W-40 would be “one-step more viscous” than a 10W-30).

There are basically two materials that get mixed together to make a modern engine oil.  One is simple refined petroleum,  which never actually wears out,  but it does get contaminated and dirty.  It has rather poor viscosity characteristics all by itself,  and very poor lubricity characteristics all by itself.  The other material is a family of liquid-plastic polymers that made from petroleum.  This stuff does wear out,  but confers much-improved viscosity characteristics,  and (even more importantly) is where most of the lubricity protection comes from.

Conventional motor oils are about 80% refined petroleum and 20% polymer additives.  “Synthetic” motor oils are mostly the polymers.  “Synthetic blends” fall in between.  Higher polymer content confers better protection,  lasts longer between oil changes,  and is far more expensive. Use something at least equal to,  or better than (more polymer content),  what your owner’s manual says.  But don’t push your oil change interval any longer than what it says,  or the warranty may be voided.

To check engine oil level,  pull out the engine oil dipstick and wipe it clean with a rag or paper towel.  Re-insert it all the way,  hold it there for a couple of seconds,  and pull it out again.  Look at where the oil level is,  relative to the “add oil” and “full” marks on the dipstick.  Look at this reading on both sides of the dipstick,  because for some engines,  they are different due to the odd angle at which the dipstick enters into the engine oil sump.  Do this twice,  or even three times,  before you decide where your oil level really falls.  Never trust the reading the first time you pull out the dipstick!  You want to see something repeatable enough to trust.  See Figure 3.


Figure 3 – Image of a Typical Engine Oil Dipstick

This one clearly shows the add and full marks,  with cross-hatching in between.  Because the add and fill marks are holes,  you can read either side of the dipstick,  and see that the reading is repeatable.  The oil level is “full” on this one.

The usual range between “add oil” and “full” is 1 quart.  If you are down to the “add oil” mark or slightly below it (heaven forbid!),  add one full quart (of the right kind of oil) through the engine oil filler cap.  If you are between the marks,  but below halfway between,  add half a quart.  If you are above halfway between,  you need add nothing.  But whatever you do,  do NOT overfill the sump!  That can blow-out oil seals,  which are expensive to repair.  You can use a cut-off piece of a quart oil container,  for an improvised funnel.  See Figure 4.


Figure 4 – Improvised Oil Fill Funnel

Figure 4 shows the cut-off top of a quart oil container being used as a convenient improvised funnel in the oil filler location.  The oil filler cap is laying next to it. 

The older the vehicle gets (burns oil),  and the more leaky it has become (drips oil),  the more often you will have to top-up the engine oil at every check. Once it is using a quart in 300-500 miles or less,  you ought to consult a mechanic.

About Oil Changes

For home mechanics who change their own oil,  and for folks who have been neglecting oil changes,  there is an oil condition test I run,  when I check the engine oil dipstick level.  This “test” will tell you about 90% of what a proper,  and expensive,  scientific laboratory test would tell you.  When you first pull the dipstick,  wipe it clean with your thumb and forefinger instead of a rag or towel.  This gets engine oil onto your thumb’s and forefinger’s fingerprints. 

Now rub them together under ordinary contact pressure.  (If you do that dry,  you can feel your fingerprint ridges dragging upon each other.)  If your oil is “good” from a lubricity standpoint,  you will not be able to feel your fingerprints drag upon each other,  no matter how much contact pressure. 

If you can just barely detect your fingerprints dragging at each other,  then your oil is just a little past its max change interval.  As an example:  if it has been about 5500 miles or so,  since it was last changed,  then try only 5000 miles  to the next change.  If at the next oil change it passes the finger test at 5000 miles,  then you are “good to go” using a 5000 mile oil change interval.  What you want is oil still providing acceptable lubricity when you change it.  If this is longer than what the owner’s manual says,  and your vehicle is out of warranty,  then feel free to use this longer interval.  But always monitor the lubricity with the finger test!  If it ever fails,  shorten your interval.

Color of the oil doesn’t much matter (even “good” oil looks dark with carbon soot blow-by,  not long after you change it).  Covering up the surface roughness of your fingerprints for a smooth-feeling “glide” is important:  that measures lubricity in a useful qualitative wayI call this test “giving your oil the finger”,  and I smile every time I think about that.  Oil that isn’t providing adequate lubricity protection is allowing engine damage to occur,  and that is very expensive!

Be sure and change the oil filter at the same time as you change your oil. A clogged-up dirty filter will bypass oil,  but the lubrication ability is reduced by the drag of that bypass,  and the bypassed oil isn’t cleaned of tiny grit particles,  which act like sand in your moving parts.  This reduces engine life.  And that gets expensive!  Filters are cheap,  it is pointless to neglect this item.

Checking the Coolant (Nearly All Modern Cars Are Liquid Cooled)

This section won’t apply to any surviving air-cooled engines from decades ago.  Those would be the old air-cooled Volkswagen beetles and buses,  and the old air-cooled Chevy Corvairs,  and some Porsches.  Nearly all modern cars are liquid-cooled.  The coolant is a mixture of water and anti-freeze concentrate.  That antifreeze concentrate is primarily ethylene glycol,  with some anti-corrosion package of additives.

First,  locate your coolant overflow bottle.  Some are low pressure (which you can open any time),  others are full radiator pressure (which you cannot open unless the engine is cool).  The cap will say,  if it is under pressure.  But these bottles all have some sort of cold fill mark and hot fill mark. 

If your engine is near dead cold,  make sure your bottle is up to the cold fill mark.  If your engine is still hot after being run,  you want to use the hot fill mark.  If your engine is just warm,  neither cold nor hot,  you want your overflow bottle level about halfway between the marks.  If it is low,  open the cap (when cold if a pressure bottle!) and fill to the appropriate mark with the right kind of coolant mix (see just below).  It really is that simple. See Figure 5.


Figure 5 – Typical Coolant Overflow Bottle

The overflow bottle shown here has clearly visible min and max marks.  Some are hard to see.  Often the level inside is hard to see.  Shining a flashlight or drop light on the bottle from the side sometimes makes the level more visible.  “Min” goes with cold engine and coolant conditions,  “Max” goes with hot.

But,  you need to know “for sure” what kind of coolant to use!  You want to match what is in the car,  even if that is different from the owner’s manual (because someone may have changed it).  There are now 3 basic types out there:  the old green coolant that uses the silicate additive package,  the orange-to-reddish “Dex-Cool” common in more recent GM vehicles that uses the organic acid additive package,  and the “Asian vehicle” type that ranges anywhere from blue to pinkish-purple (I do not know what its additive package is). 

These three are NOT COMPATIBLE and MUST NOT BE MIXED!  Mixing them leads to gunk and sludge formation that plugs up your cooling system,  which is very expensive to fix properly.   Left unrepaired,  it will quickly lead to the destruction of your engine for lack of cooling,  which is truly expensive indeed.

There are some “universal” coolants available from auto parts stores which can be used with either the older green coolant or the reddish Dex-Cool.  I’m not sure yet whether these work with the Asian vehicle coolant.  Any of the basic types or universal types can be had as concentrate,  or as pre-mixed 50-50  mixes.  The concentrate costs you less to use,  but you have to make the proper mix with clean water.  What is your time and labor worth?

What goes in the car is 50-50 mix.  If you buy the concentrate,  put some of that in,  then add an equal volume of clean water.  Better yet,  mix equal volumes concentrate and clean water into an empty container,  and then add that 50-50 pre-mix that you just made to the car.

Exceptions:  you folks who live in the snow belt probably want to use a 60-40 mix concentrate-to-water,  because it protects to a lower temperature.  In the really extreme cold,  you want exactly (and no more than) a 63-37 mix,  which is good to about -30 F (-34 C). Beyond that extreme,  you need a block heater or a heated garage.  Or both.

Be careful with the spilled coolant,  it is quite poisonous:  a tablespoon ingested can be lethal.  Pets and children are at considerable risk,  as it tastes sugar-sweet,  which suggests incorrectly to them that it is safe to ingest.

The older the vehicle,  the more likely you will need to top-up the overflow bottle at every check,  because things get old and leak.  The leaks often occur at radiator or heater hose connections,  the water pump,  or in the radiator tank connections to the radiator core cooling surfaces.  These will show dried signs or traces of leaked coolant fluid.  If you see traces of a leak,  consult a mechanic,  and soon. 

If you don’t,  your coolant system will very likely fail suddenly, while you are driving,  and this usually destroys your engine rather quickly when it does.  Few folks notice the temperature gauge suddenly rising in time,  and idiot lights are just too late by the time they come on.

If your coolant gets to be a dirty brownish color instead of its normal color,  consult a mechanic soonest about a flush and coolant change.  The green stuff is good for at most 3 years,  the red “Dex-Cool” stuff at most 5 years.  The new Asian vehicle stuff says 5 years,  but I just don’t know for sure yet how long it really lasts.  That life has little to do with the ethylene glycol base,  and everything to do with the additive package (whichever it is).  The additives are all used up in that lifetime,  letting very severe corrosion start.  That’s what the brownish gunky color is:  corrosion products and the associated sludge.

Checking the Transmission Fluid (Automatics Only)

There is nothing like this to check under the hood,  if the car has a manual transmission. 

With all automatic transmissions,  there is a procedure to do this correctly,  which is given in your owner’s manual.  Follow it. 

It usually involves running the engine at idle with the engine and transmission already mostly hot from having been driven.  The fluid level should fall between the “add” and “full” marks on the dipstick;  not below “add”,  and not above “full.   Like with the engine oil,  check both sides of the dipstick,  wiping and re-inserting.  Do this 2-3 times to ensure repeatability.  Always fill very close to the “full” mark,  never any more than that

Be sure to use the correct automatic transmission fluid.  Nearly all of these are oily liquids which are reddish in color.  The Fords use a grade of “Mercon” (like Mercon-II or Mercon-III),  the rest usually use a grade of “Dexron” (like Dexron-3). Both types are red-colored oily liquids.  Many brands you can buy at the auto parts stores meet both specs,  so you can use them in all these cars;  just make sure it meets the spec numeral (meaning the -III or the -3,  etc.) for your type (Mercon or Dexron). 

If you need to add fluid,  use a funnel and pour it down the dipstick tube,  there is no other fill location!  Take your time,  and add your fluid only a little at a time (maybe a cup to at most a pint),  so that you don’t overfill.   It takes a few minutes for the dipstick tube to clear enough,  to get a reliable reading on the dipstick,  after each addition.  See Figure 6.


Figure 6 – How to Top-Off Transmission Fluid Through the Dipstick Tube

Your transmission fluid,  though used,  should still be clean and red-looking.  If it is dark (brown to almost black),  or especially if it smells burnt or otherwise smells bad,  consult a mechanic soonest!  You might only need a fluid and filter change,  or you might need a transmission rebuild.  The longer this goes on,  the more expensive it is likely to be.

Here’s a shortcut I use to circumvent running the full hot-idle test spec for dipstick level.  Once you know the transmission is at the full mark under spec conditions,  park the car and let it cool overnight.  Then check the level on the dipstick the next morning on the cold engine,  without running it.  This level will fall a bit below the “full” mark.  Note where that level is,  and write it down,  or better yet,  draw a sketch of it!  Keep that info in the car where you can find it quickly,  and use it easily. Then you can check and top-off cold,  to that mark,  in the future.  This saves you some time and trouble doing the fluid level check in the future.  It’s not as accurate as the spec way,  but it is accurate enough.

You will usually find you don’t need to add transmission fluid.  Very old vehicles may have developed leaks that require more frequent top-off,  which you can spot by the dripped fluid stain (reddish oily spots) where you parked. 

Power Steering Fluid Check

Check your owner’s manual carefully,  to determine what this fluid really is!  Most cars use ordinary “power steering fluid”,  an oily but straw-colored clear liquid.  There are a few that use automatic transmission fluid (a red oily liquid) for this.  None would ever use brake fluid (a mostly clear liquid with a strong odor). Use ONLY the right fluid.

Open the cap and check the level.  Usually,  there is a sort of tiny dipstick built into the cap,  with an “add” mark and a “full” mark on it.  Anywhere between the marks is good.  Add a splash of the right fluid if you are low.  See Figure 7.


Figure 7 – What Most Power Steering Reservoir Caps Look Like

The power steering reservoir on the Focus had min and max marks on the side of the reservoir.  The one shown in Figure 7 is on a 1995 Ford F-150 pickup.  That cap has its own tiny dipstick built in.  Some cars have fill marks,  other cars have the cap dipstick. 

You usually will not have to add power steering fluid,  except on older vehicles that have begun to leak,  usually somewhere on the power steering pump.  If this top-up gets to be frequent,  that tells you something is either worn badly,  or really leaking badly.  Consult a mechanic at that point.

Clutch Fluid Check (Manual Transmissions Only)

Consult your owner’s manual as to whether you have one of these,  and where it is located if you do.  Automatic transmissions will not have this,  and some manual transmissions will not have it.  This fluid checks and refills the same way that power steering fluid checks and refills,  except that the fluid type may well be different.

Your owner’s manual tells you what to use for clutch fluid.  Do NOT use the wrong fluid type!  Some use power steering fluid,  some others may use an automatic transmission fluid,  and others still may actually use a brake fluid!  Be sure you know whichand do NOT use the wrong fluid!  That can cause very expensive damage!

You typically won’t have to add any clutch fluid,  until the vehicle gets old and something starts leaking.  Once you notice you have to top-up this clutch fluid up frequently,  something is definitely worn out and too leaky.  Consult a mechanic at that point.

Brake Fluid Check

This will usually be a plastic reservoir attached to a more-or-less cylindrical metal casting mounted on a big metal can that is your power brake assist (a big metal can with a vacuum diaphragm inside,  and a vacuum hose attached on the outside).  That is because nearly all modern cars have power brakes.  Some antiques do not.  Most of these reservoirs have two chambers under a common cap.  There is usually only a full-level mark.  You just fill it to the mark if it is low.  But you MUST use the right fluid!  See Figure 8.


Figure 8 – What Some Brake Fluid Reservoirs Look Like

The brake fluid reservoir shown in the figure is on the Focus.  It has an easily-visible fill mark.  Many others don’t really have translucent reservoirs.  You just open the cap and look inside.   All of them fill to near the top of the reservoir.

Most brake fluids are made of a chemical with a strong odor,  called glycol,  which is also a solvent for most car paintsDon’t spill this stuff without wiping it up!  There are 3 common grades,  your owner’s manual will tell you which you must use.  Do NOT mix them!   They are DOT-3 (the most common),  DOT-4 (for brakes that get a bit hotter on bigger vehicles),  and DOT-5A (for brakes that get much hotter on really big vehicles). 

There is also a rarely-seen silicone oil-based brake fluid named DOT-5,  which is good for both very hot brakes and for Antarctic weather temperatures.  Do NOT confuse this material with the glycol type DOT-5A!  They DO NOT MIX!  Your brakes will fail,  and must be completely flushed out and all the seals replaced,  and maybe even replace your very-expensive anti-lock brake system,  if you do mix them!  Very expensive indeed!

Most of the time,  you will not need to top-up the brake fluid at most underhood checks.  The level will drop a little (very,  very slowly) as your brake pads or shoes wear;  but it comes back up when you replace these items.  If there is a leak,  the level will drop,  requiring top-up;  but,  your brakes won’t be working right,  either.  It is very definitely time to consult a mechanic if that happens!

Glycol brake fluid (DOT-3,  DOT-4,  and DOT-5A) has a definite life,  mostly because it absorbs water from the humid air,  which then corrodes the insides of brake cylinders and fittings.  It also gets darker as it gets older,  because it oxidizes from the oxygen in the air,  making it acidic and corrosive.  You really should have the glycol-type brake fluid replaced about every 3 to (at most) 5 years.  

The much more expensive silicone oil-based DOT-5 is very rarely used,  but it does not have a limited life!  It does not absorb moisture from the air,  or darken due to oxidation.  It essentially lasts “forever”.  A few people (including me) have converted glycol systems to DOT-5 silicone systems,  to get the long life.  The seals originally intended for glycol are not harmed by the silicone,  although the reverse may not be true! 

This conversion requires a very,  very thorough flushing-out,  because the two types of fluid are utterly incompatible with each other,  and that is what does the damage to the seals and many other components.  I used a strong soapy water flush,  followed by a couple of clean water flushes,  followed by multiple 90% strength rubbing alcohol flushes,  followed by low-pressure compressed air for a day or two.  This is NOT fast,  easy work!

A note to home mechanics:  when working on your brakes,  do NOT spray the seals with WD-40 or any other petroleum-based lubricant or cleaner!  Clean them only with rubbing alcohol! The petroleum exposure makes that kind of rubber swell,  permanently.  This renders them ineffective as seals,  which means your brakes will fail to work,  requiring at least seal replacement (there is no “repair” for this). 

Windshield Washer Fluid Check

This is a bottle you likely will need to refill frequently.  It contains a mix of water and methanol,  usually dyed blue.  The methanol is an antifreeze for the water,  and it is also a solvent for the scum and dirt on your windshield.  Methanol is deadly poisonous,  so do not ingest washer fluid,  and don’t soak your hands in it!  Just fill the bottle back up to the mark if you find it low.  If you have been using your wipers a lot,  you will find it low,  a lot more frequently. 

Look at the Belts and Hoses

A hose that is either swollen or softened near its connection is a hose about to blow out.  Consult a mechanic soonest,  if you find suchIt needs replacing soonest!  There are two big radiator hoses,  and two or three small-diameter heater hoses.  The radiator hoses will suffer old age troubles more often than the heater hoses.

A belt that has cracks in the ribs or in its surface along the inside,  or is rubbed shiny along its lateral sides,  is a belt that is worn and needs replacing.  It may also squeal or squeak as it wears,  which means it is slipping (and whatever it drives is not working right).  Consult a mechanic if you find or hear any of this.  Belt replacement is not usually that big (or expensive) a job.

Air Filter Check

The air cleaner assembly usually has a top that opens up,  revealing a paper filter element inside.  There are a few cars that do not have this,  instead having a “permanent” air filter that lasts the life of the car (and is very expensive).  Paper filters are cheap,  and should be either cleaned or replaced every so often.  Your owner’s manual says how often,  but do this sooner,  if you live or work in a dusty region.

Hold the filter up between your eyes and the sun.  You should be able to see some brightness getting through the paper if the filter is OK.  If not,  try blowing the dirt clear with an air gun,  fed by shop air (80-100 psig).  That should let the brightness through;  if not,  just replace the filter.  They’re cheap.

If you don’t have access to compressed air,  then just replace the filter if you find it dirty.  As I said,  they’re cheap.  It’s not worth agonizing over.

Something Else You Should Check That Is Not Under the Hood

That would be your tire pressures. You need a good-quality tire air pressure gauge,  a fill chuck,  and a source of shop air at about 80 to 100 psig.  Do this before you have driven the car,  preferably in the cool of the morning.  Read your tire pressure gauge at least twice to make sure your reading is repeatable.  

The spec for what the tire pressures should be is usually on a sticker inside the driver’s door frame somewhere.  It’s in the owner’s manual,  too.  Often,  the pressure is a bit higher on the front tires than the rear,  because of the heavy engine up front. 

Do not forget to check the spare in the trunk,  even if it one of the little “doughnut” spares.  The spare does you no good when you are changing a flat,  if it is not inflated sufficiently.

The usual pencil-type tire gauge is the cheapest,  but also the least accurate.  They get too inaccurate to rely upon,  after only a very few years after you buy one.  Round dial gauge-type tire pressure gauges stay accurate for long useful lives,  but are the most expensive.  The choice is yours.  Just be aware of the accuracy problem.

Another Thing To Check Every Now and Then

That would be how worn your tires are.  Stick a penny into one of the tread grooves such that the top of Abe Lincoln’s head is toward the center of the wheel.   If there is clearance between the tread surface and the top of Lincoln’s head,  your tires are too worn to be legal at inspection time.  They will also skid very,  very easily on the ice,  or in heavy rain.  Worn tires are dangerous.  Just go get new tires.

The other thing to worry about is how evenly your tires are wearing.  Worn-out suspension components or an out-of-alignment suspension will cause weird-looking asymmetries to how your tires wear.  If you ever see anything like this,  consult your mechanic soonest!  This kind of thing wears tires into scrap very quickly,  and tires are NOT cheap!

The last thing to worry about is when you see even wear across the tread,  and on both wheels left to right,  but a bit more wear on the heavier front than on the back wheels.  That just means you haven’t been rotating your tires.  So go get them rotated,  front-for-back,  keeping lefts on the left,  and rights on the right.  Be sure to adjust tire pressures appropriately.